Application of powder failure testing equipment in assessing effect on glidants on flowability of cohesive pharmaceutical powders.

Powder failure testing equipment was used successfully to study the effect of glidants on the flowability of two cohesive pharmaceutical powders, lactose and calcium hydrogen phosphate, using the flow factor as the flowability parameter. Fine silica, magnesium stearate, and purified talc were investigated as glidants; for each host powder-glidant mixture, an optimum concentration of glidant was observed beyond which no further increase in flowability occurred. The order of efficiency of glidants for both host powders was fine silica greater than magnesium stearate greater than purified talc. The mode of action of the three glidants is discussed.


Rapid, sensitive colorimetric method for determination of ethinyl estradiol.

A colorimetric procedure, based on the formation of an azo dye by condensation of diazotized 5-chloro-2,4-dinitroaniline with ethinyl estradiol, was developed. An alkaline solution of ethinyl estradiol is reacted with the reagent, and the resulting color is measured at 450 nm. Absorbance versus concentration is linear up to 10 mug/ml; the lower limit of detection is 1 mug/ml under the conditions studied. Replicate analysis showed good agreement, and an average recovery of 99.6 +/- 0.3% was obtained for analyses of synthetic mixtures. Vitamins and minerals likely to be present along with ethinyl estradiol in certain geriatric formulations, as well as ordinary tablet excipients and coating materials, do not interfere with the precision of the method or development of the color. The method is applicable to progestin-estrogen preparations. Assay results on various single-component as well as contraceptive commercial samples are reported.


Automated constant-current coulometric assay system for ascorbic acid and sodium ascorbate.

The performance of an automated constant-current coulometric system for the assay of ascorbic acid and sodium ascorbate is described. After loading, it is capable of analyzing 25 samples and printing out the titer values with no operator attention for 2.5 hr. Under optimum conditions, ascertained by evaluating various electrochemical parameters, the accuracy and precision (95% ts) were found to be +/- 0.3%.


Automated spectrophotometric assay of cefazolin.

An automated, stability-indicating, UV spectrophotometric assay for cefazolin is presented. The method employs a reaction with hydroxylamine and derives its stability-indicating power through comparison of reacted and unreacted aliquots of the sample. A double-probe sampling procedure is used. Good agreement with microbiological assays is obtained, and the coefficient of variation is about 1%.


GLC determination of heroin and its metabolites in human urine.

Heroin and its metabolites, 6-monoacetylmorphine, morphine, and normorphine, were determined in human urine with a GLC procedure. Heroin was extracted with chloroform at pH 4.5 and chromatographed at a temperature programmed from 200-250 degrees by 8 degrees/min. 6-Monoacetylmorphine and morphine were extracted with ethylene dichloride containing 30% isopropanol at pH 8.5, and normorphine was extracted at pH 10.4 wtih the same solvent. The extract was derivatized with trimethylsilylimidazole and chromatographed at 230 degrees for the determination of 6-monoacetylmorphine and morphine and at 220 degrees for normorphine and morphine.


Synthesis of 2-(4-arylthiosemicarbazidocarbonylthio)benzthiazoles and their monoamine oxidase inhibitory and anticonvulsant properties.

Ten 2-(4-arylthiosemicarbazidocarbonylthio)benzthiazoles were synthesized, characterized, and evaluated for their monoamine oxidase inhibitory and anticonvulsant activities. All substituted benzthiazoles inhibited activity of monoamine oxidase in rat brain homogenate where the degree of enzyme inhibition was higher with kynuramine as compared to tyramine and 5-hydroxytryptamine as the substrates. All substituted benzthiazoles possessed measurable anticonvulsant activity against pentylenetetrazol-induced convulsions.


Anti-inflammation mechanism of extract from Eisenia bicyclis (Kjellman) Setchell.

An extract from Eisenia bicyclis, previously shown to possess anti-inflammatory activity, was found to stabilize lysosomal membranes in vitro as determined by measurement of inhibition of the marker enzyme beta-glucuronidase. Some anti-inflammatory activity was also due to counterirritancy.


Synthesis and antimicrobial activity of N-substituted N'-cyano-S-(triorganostannyl)isothioureas.

Six N-substituted N'-cyano-S-(trimethylstannyl)isothioureas were synthesized by the reaction of (trimethylstannyl)cyanamide with various organic isothiocyanates. The IR spectrum of each compound was obtained over the 4000-30-cm(-1) range, and some bands were assigned. The six new compounds and five previously synthesized N-substituted N'-cyano-S-(triphenylstannyl)isothioureas were tested for and were found to exhibit antifungal activity. N-Phenyl-N'-cyano-S-(triphenylstannyl)isothiourea was also investigated for antibacterial activity and was observed to be especially inhibitory toward Gram-positive species. The antimicrobial activity of two compounds was compared to that of the oxygen analogs of these compounds.


New synthesis of (RS)-carnitine chloride.

A four-step synthesis of (RS)-carnitine chloride was developed using extremely mild reaction conditions and versatile intermediates. Crotyl chloride was converted to tert-butyl 3-butenoate using tert-butyl alcohol and triethylamine in ether. Treatment of tert-butyl 3-butenoate with m-chloroperbenzoic acid in chloroform afforded tert-butyl 3,4-epoxybutyrate. Reaction of this compound with trimethylamine hydrochloride in methanol, followed by mild acid hydrolysis of the tert-butyl ester, afforded (RS)-carnitine chloride.


Linear drug release from laminated hydroxypropyl cellulose-polyvinyl acetate films.

Release of drug from a single-layer film containing dispersed drug follows a diffusion-controlled matrix model, where the quantity released per unit area is proportional to the square root of time. The kinetics may be made linear with time (zero order) by laminating a second film without drug to the releasing side of the film with dispersed drug. In this manner, the drug layer serves as a reservoir and controls the duration of drug release, while the nondrug layer functions as a rate-controlling membrane. Zero-order drug release was demonstrated in such laminated films using 18-45 percent pentobarbital, methapyrilene, or salicylic acid contained in hydroxypropyl cellulose as the reservoir layer and mixtures of hydroxypropyl cellulose and polyvinyl acetate as the membrane layer. Inverse relationships between the release rate and membrane thickness and between the logarithm of the rate and the percentage of polyvinyl acetate in the membrane layer were observed. Of the three drugs tested, salicylic acid gave the fastest release rates while pentobarbital gave the slowest.


Acylation of ascorbic acid in water.

The acylation of ascorbic acid by acetic anhydride was studied in water at 25 degrees. The results indicate that the initial products of reactions between these two compounds were acetic acid and 3-o-acetylascorbic acid. The latter product then underwent two parallel reactions: hydrolysis to ascorbic and acetic acids and an intramolecular O leads to O acyl migration to yield-O-acetylascorbic acid. The former reaction was predominant at pH values below 4, whereas the latter reaction predominated at pH values between 4 and 7. These results are used as a basis for questioning the structural assignments previously made to some ascorbic acid esters.


GLC analysis of hydrochlorothiazide in blood and plasma.

GLC with electron-capture detection was successfully applied to the analysis of hydrochlorothiazide in human blood and plasma with a sensitivity (0.05 mug/ml) suitable for use with persons on therapeutic dosage levels. On-column methylation with trimethylanilinium hydroxide in methanol was employed to convert hydrochlorothiazide and its bromo analog, which served as the internal standard, to their tetramethyl derivatives.


Ocular evaluation of polyvinyl alcohol vehicle in rabbits.

The flow properties and viscosity of the vehicle into which drugs are incorporated can be determining factors in the bioavailability of topically applied ophthalmic drugs. It is shown, in rabbits, that when polyvinyl alcohol and methylcellulose are compared on a viscosity basis, there is essentially no difference in the two vehicles with regard to their influence on ocular drug bioavailability. Moreover, the rate of drainage loss for polyvinyl alcohol solutions, as determined by the radioactive technetium technique, compares favorably to methylcellulose solutions of similar viscosity. The relationship between viscosity and contact time or drainage loss of a drug is not a direct one, but an optimum viscosity range exists for polyvinyl alcohol solutions. This optimum range of 12-15 cps in rabbits is identical to that found for methylcellulose and differs considerably from the commonly employed viscosity in commercial preparations. Based on the methylcellulose-polyvinyl alcohol comparison, it appears that vehicles exhibiting or approximating Newtonian flow properties show comparable effects as ophthalmic vehicles. Finally, a discussion of non-Newtonian vehicles and their expected behavior in the eye is presented.


Comparative anti-inflammatory, analgesic, and antipyretic activities of 7-chloro-3,3a-dihydro-2-methyl-2H,9H-isoxazolo-(3,2-b)(1,3)-benzoxazin-9-one and 5-chlorosalicylic acid in rats.

Evidence is presented which indicates that 7-chloro-3,3a-dihydro-2-methyl-2H,9H-isoxazolo-(3,2-b) (1,3)-benzoxazin-9-one (I) and 5-chlorosalicylic acid, its major metabolic end-product, are equally effective as anti-inflammatory and antipyretic agents, while the former is a somewhat more effective analgesic than its metabolite in the rat. However, at the equimolar doses used in this study, I is not ulcerogenic, while 5-chlorosalicylic acid does possess this untoward effect in the fasted rat. Moreover, the LD50 for 5-chlorosalicylic acid (261.0 mg/kg) is approximately 6.5 times less than that of I (1710.0 mg/kg) in the nonfasted rat. These results support the postulation that 5-chlorosalicylic acid is most likely responsible for the pharmacological activity displayed by I; i.e., the latter acts as a carrier or delivery system, allowing attenuation of the toxic properties of its active metabolite.


Pharmacokinetic model for a primary antibody response.

Antigen distribution and clearance studied in vivo may be viewed as a pharmacokinetic problem complicated by the intervention of the immune response. A model characterizing the clearance of the simple antigen phiX174 from the bloodstream of various experimental animals, as well as the subsequent serum antibody response, was developed. The present model is the simplest of the possible models and no doubt will have to be modified when considering more complex antigens, additional distribution modes, and differences in antibody reactivity. For the primary (IgM) immune response, however, early events in the immunological response can be adequately accounted for in a consistent and quantitative manner.


Antihemolytic and anticonvulsant activities of 1-(2,4-dichloro/2,4,5-trichlorophenoxyacetyl)-4-alkyl/arylthiosemicarbazides and their inhibition of NAD-dependent oxidations and monoamine oxidase.

Several 1-(2,4-dichloro and 2,4,5-trichlorophenoxyacetyl)-4-alkyl/arythiosemicarbazides were synthesized and characterized by their sharp melting points and elemental analyses. All substituted thiosemicarbazides protected in vitro hypoosmotic hemolysis of dog red blood cells. These thiosemicarbazides selectively inhibited nicotinamide adenine dinucleotide (NAD)-dependent oxidation of pyruvate and alpha-ketoglutarate, while NAD-independent oxidation of succinate was not affected. These compounds inhibited the activity of monamine oxidase in rat brain homogenate, and the degree of inhibition ranged from 26.5 to 89.2 percent at a final concentration of 0.03mM, with kynuramine as the substrate. Almost all thiosemicarbazides possessed anticonvulsant activity; protection against pentylenetetrazol-induced convulsions in mice ranged from 10 to 70 percent at a dose of 100 mg/kg ip. These results provided evidence of some similarity between the membrane-stabilizing property of these substituted thiosemicarbazides with their ability to exhibit selective inhibition of NAD-dependent oxidations and inhibition of monoamine oxidase. On the other hand, the anticonvulsant activity possessed by these substituted thiosemicarbazides was unrelated to their in vitro antihemolytic and enzyme inhibitory properties.


Assay of flucytosine and furosemide by high-pressure liquid chromatography.

A high-pressure liquid chromatographic method for the analysis of flucytosine and furosemide concentrations in biological fluid is described. The separations were carried out on a pellicular cation-exchange resin eluted with an ammonium phosphate buffer. Detection of elution peaks was by UV absorption at 280 nm and fluorescence monitoring. Advantages of the method are specificity, minimal preanalysis sample workup, and small sample size.


Maternal-fetal transfer of 14C-di-2-ethylhexyl phthalate and 14C-diethyl phthalate in rats.

14C-Di-2-ethylhexyl and 14C-diethyl phthalates were administered intraperitoneally to pregnant rats on either Day 5 or 10 of gestation. Rats were sacrificed at 24-hr intervals starting on Days 8 and 11, respectively; maternal blood, fetal tissue, amniotic fluid, and placentas (whenever possible) were obtained. The 14C-activity of each sample was determined by scintillation counting. It was found that both diesters and/or their metabolic products were present in each of these compartments throughout the gestation period, thus suggesting that the embryo-fetal toxicity and teratogenesis reported previously could be the results of a direct effect of the compound (or its metabolites) upon developing embryonic tissue. Additionally, the reduction in concentration of 14C from these tissues as a function of time was found to fit a first-order excretion curve. From this model curve, the half-life for both compounds was calculated; the average was about 2.33 days for di-2-ethylhexyl phthalate and 2.22 days for diethyl phthalate.


Metabolism of minoxidil, a new hypotensive agent I: absorption, distribution, and excretion following administration to rats, dogs, and monkeys.

Minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide), a potent new hypotensive agent, was 14C-labeled in the 2-position of the pyrimidine ring in 17 percent yield from Ba14CO3. This material was used to study the absorption, distribution, and excretion of the drug in rats, dogs, and monkeys. Following oral administration of a single dose, the drug was rapidly and well absorbed and rapidly eliminated by each species as judged by plasma levels and urinary excretion of unchanged drug and total drug-related materials. Chronic oral administration of the drug at a high level (10 mg/kg) for 30 days slightly increased the rate of clearance of minoxidil and minoxidil-related material from circulation. Water diuresis, resulting from water loading of dogs, caused an even greater increase in the rates of disappearance of the drug and drug-related material. Whole-body autoradiography studies in rats showed that minoxidil was rapidly distributed following its oral and intravenous administration. It was subsequently concentrated, primarily in the excretory system. Minoxidil-related material was detected in aorta walls, but not in the CNS, following both routes of drug administration.


Antiradiation compounds XV: condensations of carbon disulfide with amino, chloro, cyanomethyl, and sulfonamido heterocycles.

Condensations of carbon disulfide were carried out with amino, chloro, and diamino heterocycles to give condensed ring thiazoline-2-thiones and imidazoline-2-thiones, with cyanomethyl heterocycles to give dithio acid derivatives, and with heterocyclic sulfonamides to give sulfonyldithiocarbamates. Of several examples tested, pyrido[3,2-d]thiazoline-2-thione, disodium 2-(5-chloro-2-thienyl)-3,3-dimercaptoacrylonitrile, triethylammonium 4-sulfamoylphenyldithiocarbamate, ammonium beta-phenethyldithiocarbamate, and methyl N-(thiophene-2-sulfonyl)dithiocarbamate, only the last-named compound showed any radiation protection for mice. Several compounds gave negative tests for antimalarial activity.


Analogs of the anorexic mazindol.

Mazindol, 5-(p-chlorophenyl)-2,5-dihydro-3H-imidazo[2,1-a]isoindol-5-ol, has been shown to be an effective anorexic. To explore the structure-activity relationships, several 1-ethyl-3-substituted-4-aryl-4-hydroxyindeno[1,2-c]pyrazoles were prepared and subjected to various animal screens. The 1-ethyl-3-tert-butyl-4-aryl-4-hydroxyindeno[1,2-c]pyrazoles are capable of significantly depressing forced and spontaneous motor activity in mice but have low LD50's. Two of these compounds were tested in an Ehrlich ascites tumor screen. The 1-ethyl-3-phenyl-4-aryl-4-hydroxyindeno[1,2-c]pyrazoles depressed forced and spontaneous motor activity at low doses and were relatively nontoxic.


High-pressure liquid chromatographic analysis of penicillin G potassium and its degradation products.

An anion-exchange high-pressure liquid chromatographic system capable of separating penicillin G potassium from five of its degradation products was developed. The retention times were: penicillin G potassium, 17.5 min; DL-penicillamine, 4.5 min; benzylpenilloic acid, 7.0 and 8.0 min; benzylpenamaldic acid, 13.0 min; benzylpenicilloic acid, 19.5 min; and benzylpenillic acid, 22.0 min. In addition, the system permits quantification using linear calibration curves.


Differentiating nonaqueous titration of aspirin, acetaminophen, and salicylamide mixtures.

Mixtures containing aspirin, acetaminophen, and salicylamide were assayed potentiometrically by nonaqueous titration. The difference in pKa values for these weak acids was sufficient to permit successful differentiation. The titrant was tetrabutylammonium hydroxide, and the titration solvent was dimethylformamide. The procedure was applied to commercial dosage forms.


Analysis of individual thyroid tablets.

A procedure was developed for the assay of individual thyroid tablets or composite samples equivalent to as little as 0.033 g (0.5 gr) of thyroid. The sample is ignited in a closed atmosphere of oxygen and, after a series of redox reactions, the iodine is determined spectrophotometrically as the triiodide ion. The results agree well with those obtained by the USP thyroid tablet assay.


NMR spectroscopic analysis of 2-mercapto-5-methyl-1,3,4-thiadiazole in cefazolin.

A rapid, sensitive, and accurate method for the quantitative analysis of 2-mercapto-5-methyl-1,3,4-thiadiazole in cefazolin is presented. The method utilizes NMR spectroscopy and is based on the difference in the chemical shift of the methyl protons on free thiadiazole and the thiadiazole moiety of cefazolin.


Unit-dose assay of tropine alkaloids and their synthetic analogs.

A charge-transfer spectrophotometric method was developed for unit-dose assay of the tropine alkaloids and some of their synthetic analogs. The high molar absorptivities of the charge-transfer bands of the alkaloids with iodine in ethylene dichloride resulted in improved recoveries and good precision, particularly at the low dose levels of pediatric and hypodermic tablets.


Colorimetric determination of isoniazid with 9-chloroacridine.

A colorimetric method based on the interaction between isoniazid and 9-chloroacridine was developed. Analytical solutions are shaken for 30 min at 50 degrees, and the absorbance is measured at 500 nm. The procedure is sensitive for isoniazid in the 10(-5) M range. The method was applied to the analysis of isoniazid in pharmaceutical dosage forms and found to be comparable to the USP XVIII assay. Preliminary investigations suggested that the procedure is useful for the determination of free isoniazid in urine and plasma samples containing isoniazid metabolites.


Determination of polythiazide in pharmaceutical dosage forms by high-pressure liquid chromatography.

A method is presented for the quantitative analysis of polythiazide tablets by high-pressure liquid chromatography. The powdered tablets are extracted with methanol, containing quinoline as the internal standard, and assayed by comparison of peak heights after liquid chromatography. The chromatographic conditions employed may be adapted for the determination of many other thiazide and nonthiazide diuretics.


Sieve cuts as monodisperse powders in dissolution studies.

Dissolution profiles are calculated for sieve cuts of varying width based on a derived equation, which assumes diffusion rate-limited dissolution under sink conditions from spherical particles. It is shown that even the narrowest of sieve cuts may vary from cube root law expectations by as much as 3 percent, depending on the distribution of particles across the cut. Much smaller deviations from the cube root law occur when the weight distribution of diameters is constant across a sieve cut. It is concluded that when experimental data are treated on the assumption that sieve cuts act like monosized powders, errors generally will be acceptable except in cases of critical tests of dissolution rate theory. In those cases, more information about the powder distribution should be given.


Comparison of analytical methods for residual ethylene oxide analysis.

A round-robin study compared four methods of residual ethylene oxide analysis. Results from the six participating laboratories, along with a statistical treatment of the data, are presented.


Effects of nitrogen dioxide and 3-methylcholanthrene on pulmonary enzymes.

Guinea pig lung phenol-O-methyltransferase, catechol-O-methyltransferase, and benzpyrene hydroxylase activities were examined after nitrogen dioxide and 3-methylcholanthrene treatment. While benzypyrene hydroxylase activity was enhanced by 3-methylcholanthrene, none of the pulmonary enzyme activities was altered after exposure to either 40 or 70 ppm of nitrogen dioxide for 2 hr.


Synthesis and blood pressure lowering activity of benzylic ethers of 2-diethylaminoethanol and a related diamine.

Based upon the unpublished finding that 3'-hydroxy-4'-(beta-diethylaminoethoxy)-3',4'-dihydroseselin possessed a potent blood pressure lowering effect in the cat at a dose of 1 mg/kg, the present study examined the activities of several related compounds. These compounds were derived by dissection of the parent compound to give four benzylic ethers of 2-diethylaminoethanol and a diamine, derived by replacing the ether oxygen of the parent compound with an N--CH3 function. The simplest compounds were the benzyl and 2,6-dimethoxybenzyl ethers of the aminoalcohol. Closely related to the benzyl compound was a congener with a hydroxymethyl group on the benzylic carbon. The beta-diethylaminoethyl ether of 4-chromanol was the most complex of the ethers. The blood pressure measurements were carried out on male cats and compared to papaverine hydrochloride as a standard. In all cases, the most potent blood pressure lowering activity resided in the parent compound, which was not greatly superior to the diamine but substantially more active than the other compounds.


Cyanogen condensations as a route to 3-amino-2-imino-1,3-benzothiazin-4-ones with CNS depressant potential.

Seven new 3-amino-2-imino-1,3-benzothiazin-4-ones, prepared from the condensation of cyanogen and 2-mercaptobenzhydrazides, were evaluated in a neuropharmacological mouse profile. CNS depression was observed in several members of the class.


Fluorinated quinazolones III: synthesis and CNS depressant activity of fluorinated quinazolone derivatives.

The synthesis of 2-allylthio-3-(4'-fluorophenyl)-5,6,7,8-tetrafluoro-4-quinazolone, 2-n-propylthio-3-(4'-fluorophenyl)-5,6,7,8-tetrafluoro-4-quinazolone, 3-(4'-bromophenyl)-5,6,7,8-tetrafluoro-2,4-quinazolinedithione, and seven fluorinated 2-alkyl/phenyl-3-aryl-4(3H)-quinazolones is described. The synthesized compounds were screened for CNS depressant activity using pentobarbital sleeping time, pentylenetetrazol convulsions, and condition avoidance test as the parameters. Most of the screened compounds exhibited significant depressant activity.


Monoamine oxidase inhibiting activity of a series of (+/-)-4-methoxy-beta-hydroxyphenethylamines.

The synthesis and selected pharmacological testing of (+/-)-4-methoxy-beta-hydroxyphenethylamine [1-(4-methoxyphenyl)-2-aminoethanol] and its N-methylated derivatives are presented. Members of this series were found to exert partial prevention of reserpine-induced hypothermia in mice and to inhibit monoamine oxidase in Warburg studies. Activity was essentially dose dependent. The secondary amine was the most active member of the series. The tertiary amine was least active, and the primary amine exhibited intermediate activity.


Influence of carbon monoxide, hypoxic hypoxia or potassium cyanide pretreatment on acute carbon monoxide and hypoxic hypoxia lethality.

Pre-exposure of mice to 500 or 1000 ppm of carbon monoxide (CO) for 4 hours resulted in a significant decrease in lethality induced by exposure to 2500 ppm of CO 24 hours later. Pre-exposure to CO had no effect on lethality induced by hypoxic hypoxia (low inspired O2 tension) or potassium cyanide (KCN). Pre-exposure to 10% O2 for 4 hours significantly decreased lethality induced 24 hours later by CO or 7% O2 exposures lethality induced 24 hours later by CO or 7% O2 exposures but had no effect on KCN-induced lethality. Pretreatment with a nonlethal dose of KCN had no significant effect on lethality induced 24 hours later by exposure to CO (2500 ppm), 7% O2 or KCN. The alterations in CO lethality were not associated with alterations in carboxyhemoglobin levels. Studies of oxygen consumption and indicators of oxygen delivery to tissues (P50 and red blood cell 2,3-diphosphoglycerate) failed to provide any evidence of pretreatment alteration. Examination of blood lactate, pyruvate and lactate/pyruvate ratios in control and pre-exposed mice after a short exposure to 2500 ppm of CO showed significantly lower lactate and lactate/pyruvate ratios in the pre-exposed mice as compared to controls. These data suggest that animals pre-exposed to 1000 ppm of CO and 10% O2 are less hypoxic than non-pre-exposed animals even through their oxygen delivery system is unchanged.


Effects of glucagon and other peptides on fixation of CO2 by rat liver mitochondria.

Glucagon and glucagon fragments from the carboxyl terminal end of the protein act at 0.01 to 0.1 mM concentrations on isolated rat liver mitochondria to sustain the rate of fixation of CO2 in the presence of pyruvate. The rate of decarboxylation of pyruvate is also increased by these substances. Similar effects are found with bacitracin, vanocomycin and cephalothin but not with any other of the proteins, peptides and antibiotics tested. The action of glucagon requires the presence of added magnesum ion. The addition of glucagon results in a better maintenance of adenosine triphosphate (ATP), and it leads to a greater degree of swelling of the mitochondria during the incubation. The effect of glucagon is partially mimicked by atractyloside, but it appears that glucagon is not exerting its effect by an atractyloside-like action. Added ATP obliterates the effect of added glucagon by sustaining fixation of CO2 However in incubations made in the presence of lower than usual levels of inorganic phosphate (2 mM vs. 8 mM) an effect of glucagon can be seen in the presence of ATP.


Effect of 3-(p-trifluoromethylphenoxy). N. N. methyl-3-phenylpropylamine on the depletion of brain serotonin by 4-chloroamphetamine.

3-(p-Trifluoromethylphenoxy)-N-methyl-3-phenylpropylamine (Lilly 110140), when injected into rats at i.p. doses of 1 to 10 mg/kg, prevented the lowering of brain serotonin by 4-chloroamphetamine. The duration of 110140 action was very long, significant antagonism of 4-chloroamphetamine action being apparent still at 48 hours after a single dose of 10 mg/kg of 110140. The N,N-dimethyl tertiary amine derivative was as effective as 110140 itself in antagonizing serotonin depletion by 4-chloroamphetamine, but other structurally related compounds has less activity or were inactive. Likewise, six tricyclic antidepressant drugs injected at 10 mg/kg i.p. did not antagonize the action of 4-chloroamphetamine. When injected into rats whose brain serotonin levels had already been depleted by 3-hour pretreatment with 4-chloroamphetamine, 110140 terminated the action of 4-chloroamphetamine and permitted serotonin levels to return to normal. Lilly 110140 did not antagonize the depletion of brain serotonin or norepinephrine by reserpine, which implies that reserpine does not require the membrane pump for entry into the neuron. The depletion of brain serotonin, but not norepinephrine, by alpha-ethyl-3-hydroxy-4-methylphenethylamine (H75/12) was blocked by 110140. In contrast to chlorimipramine, 110140 did not antagonize the depletion of norepinephrine levels in heart and spleen by 6-hydroxydopamine. The data suggest that 110140 is a specific drug for inhibiting uptake into serotoninergic neurons in the brain.


A new selective inhibitor for uptake of serotonin into synaptosomes of rat brain: 3-(p-trifluoromethylphenoxy). N-methyl-3-phenylpropylamine.

3-(p-Trifluoromethylphenoxy)-N-methyl-3-phenylpropylamine (Lilly 110140) competitively inhibited the uptake of serotonin (5-HT), norepinephrine (NE) and dopamine into synaptosomes of rat brain with Ki values of 5.5 x 10-minus8, 9.5 x 10-minus6 and 1.3 x 10-minus5 M, respectively. Aiming for a more effective inhibitor of 5-HT uptake, we found the trifluoromethyl group in the phenoxy ring was most favorable at the para-position and was better than other substituting groups including fluoro, chloro, methyl and methoxy groups. The N-demethylated (primary amine) and the N.N-diemthylated (tertiary amine) derivatives inhibited the uptake of monoamines with the same effectiveness as Lilly 110140 (a secondary amine). The uptake of 5-HT into synaptosomes was significantly inhibited 15 minutes after an intraperitoneal administration of Lilly 110140. The inhibition persisted for a 24-hour period. NE uptake in vitro maintained a normal rate during the entire time course. Lilly 110140 likewise had no effect on the in vitro and in vivo accumulation of 3-H-tryptophan in the brain. The effect of Lilly 110140 and the tricyclic drug, chlorimipramine, was compared. Although chlorimipramine inhibited the uptake of 5-HT into synaptosomes with same effectiveness as Lilly 110140 in vitro, it reduced the uptake of both 5-HT and NE in vivo. Chlorimipramine exerted its greatest inhibition on the two uptake processes in the 1st hour and none by the 4th hour. Unlike the tricyclic drugs, imipramine, chlorimipramine, desipramine and chlordesipramine, Lilly 110140 and its primary amine derivative did not block the in vivo uptake of NE into rat heart. The present study suggests that Lilly 110140 is a potent and selective inhibitor for uptake of 5-HT into synaptosomes of rat brain.


Effects of lithium chloride on parameters biosynthetic capacity for 5-hydroxytryptamin in rat brain.

Administration of lithium chloride to rats resulted in a biphasic, temporally related alteration in the brain's biosynthetic capacity for 5-hydroxytryptamine (5-HT). After 3 to 5 days of drug administration, the Vmax of the high affinity uptake of [14-C]tryptophan into striate nerve ending synaptosomes increased to 140% of control values. The stimulated uptake of radioactive precursor apparently resulted in an augmentation of tryptophan-to-5-HT conversion activity of the same magnitude in these synaptosomes. These events were succeeded by an apparently compensatory decrease in the Vmax of midbrain cell body and nerve-ending solubilized tryptophan-5-hydroxylase (EC 1.99.1.4). After 21 days of drug administration, [14-C]tryptophan uptake remained above control levels, but striate synaptosomal conversion activity had returned to control levels. In contrast, soluble midbrain and solubilized striate synaptosomal enzyme activity remained significantly below control values. In vitro lithium chloride at 10 or 53 mM had no effect on soluble tryptophan hydroxylase activity, but either concentration of lithium chloride significantly enhanced the uptake of [14-C]tryptophan into striate synaptosomes, and consequently also the synaptosomal conversion of tryptophan to 5-HT. Increasing tryptophan levels either by preincubation of synaptosomes with L-tryptophan or by administration of L-tryptophan loads (20-60 mg/kg) resulted in augmented [14-C]tryptophan uptake and conversion activity. The sequence of events that we observed after lithium treatment is consistent with receptor-mediated neuronal feedback regulation of tryptophan hydroxylase activity after stimulation of tryptophan uptake and conversion of 5-HT.


Correlation between brain levels and biochemical effects of the optical isomers of p-chloroamphetamine.

The biochemical effects of d- and l-p-chloroamphetamine (PCA) were compared with the brain levels of the unchanged drug at various times after a single injection. Initially both isomers produced rapid and pronounced decreases in the whole brain levels of serotonin and 5-hydroxyindoleacetic acid, tryptophan hydroxylase activity and the synaptosomal uptake of 3-H-serotonin. At later times (e.g., 2 weeks), the effects of the d-isomer were much more pronounced than were those of the l-isomer. At intermediate times (2-4 days), a variable and dose-dependent recovery of synaptsomal uptake activity and tryptophan hydroxylase activity occurred after d-PCA. In both whole brain and forebrain, long-term reductions in these activities were found. However, in the midbrain, an area containing the cell bodies of serotonergic neurons, only a slight initial decrease in tryptophan hydroxylase activity occurred. The whole brain levels of the two isomers were equal from 4 to 96 hours after injection and declined exponentially in a single monophasic manner monophasic decine of the levels of PCA was found in forebrain and midbrain samples. Thus, the initial and long-term effects of PCA are apparently mediated by different mechanisms. The former is correlated with the brain levels of the unchanged drug; the latter is not. The lack of any indication of a biphasic decay curve after 10 half-lives and the intermediate recovery of serotonergic function do not support a reserpine-like mechanism for the long-term effects of PCA. Instead, a mechanism related to neurotoxicity is proposed.


Determination and characterization of the antinociceptive activity of intraventricularly administered acetylcholine in mice.

Antinociceptive activity of intraventricularly administered acetylcholine was quantitated in mice by the tail-flick and phenylquinone tests. Acetylcholine was administered intraventricularly under light ether anesthesia in a 5 mul volume of sterile saline and mice were retested 10 minutes after the operation. A dose-response curve was established for acetylcholine (ED50 equals 7.3 mug) which was potentiated by intraventricular neostigimine and blocked by intraperitoneal atropine, but not by atropine methyl nitrate or mecamylamine. The antinociceptive effect of morphine was potentiated by intraventricularly administered acetylcholine. The acetylcholine-induced antinocieption was blocked by five narcotic antagonists in the same rank order of potency in which they antagonized the effects of morphine. However, the stereo-specificity of two narcotic antagonists, pentazocine and cylcazocine, was reversed in blocking acetylcholine and morphine-induced antinociception. The results of this study have established a phenomenon of acetylcholine-induced antinociception and identified the central, muscarinic nature of this response. In addition, several experiments have demonstrated similarities between this phenomenon and morphine-induced antinociception. These data implicate the possible involvement of central cholinergic mechanisms in the antinociceptive action of morphine.


Contrasting effects of morphine on schedule-controlled behavior in the chimpanzee and baboon.

Schedule-controlled key pressing was maintained in two chimpanzees and three baboons under a multiple 10-minute fixed-interval (FI 10-min) 30-response fixed-ratio (FR 30) schedule of food delivery. Characteristic rates and patterns of responding were maintained under the FI and FR schedules, and the performance of the two species differed in no systematic way. The acute i.m. administration of morphine (0.1-3.0 mg/kg) prior to selected 2-hour sessions increased mean rates of responding under the FI schedule in the chimpanzee, but decreased responding in the baboon. At a dose of 3.0 mg/kg of morphine, responding under the FI schedule in the chimpanzee increased 4-fold and responding in the baboon decreased to less than 25% of control levels. Mean response rates under the FR schedule were also increased by morphine in the chimpanzee, but responding under the FR schedule was little affected in the baboon except at the higher doses which decreased response rates below control levels. Respiratory rate in the chimpanzee was markedly depressed at 5.6 mg/kg of morphine and one chimpanzee died. A similar depression of respiration was not observed in the increase responding in a nonhuman primate, the chimpanzee, and that the behavioral effects of morphine in the chimpanzee are qualitatively different from the effects in monkeys.


Further studies on self-administration of antipyretic analgesics and combination of antipyretic analgesics with codeine in rhesus monkeys.

The possible reinforcing effect of acetylsalicylic acid (ASA) was studied in a group of rhesus monkeys that had no history of self-administration of drugs. Rates of lever pressing were compared under conditions in which each lever-pressing response resulted in an infusion of saline, an infusion of saline plus delivery of a food pellet or an infusion of ASA (0.4, 1.0, 2.5 OR 5.0 MG/KG /infusion). Responding was engendered and maintained by the delivery of food pellets but not by infusions of saline alone nor by ASA; however, responding was subsequently engendered and maintained in these monkeys by codeine (0.05 mg/kg/infusion). In another group of monkeys that had been trained to respond under a 10-response fixed-ratio schedule of i.v. infusions of codeine, the possible reinforcing effects of aminophenazone, phenylbutazone and of combinations of each of these drugs with codeine were studied. Aminophenazone and phenylbutazone (0.4-5.0 mg/kg/infusion) did not maintain responding previously engendered by codeine. Mixtures of aminophenazone and phenylbutazone with codeine decreased the number of codeine self-administrations. Thus, codeine intake was reduced when aminophenazone and phenylbutazone were added to codeine in the solution to be self-administered. These experiments suggest that antipyretic analgesics are not effective in reinforcing behavior in the rhesus monkey.


Relationship of brain morphine levels to analgesic activity in acutely treated mice and rats and in pellet implanted mice.

The relationship of brain morphine concentration, determined fluorometrically, to tail-flick activity was investigated after acute and chronic morphine treatment of mice and acute treatment of rats. Brain morphine levels were quantitatively related to the analgesic effect on acute administration, with levels of 100 and 140 ng/g of tissue corresponding to the ED50 in mice and rats, respectively. Over a 90-minute time course after acute s.c. injection, the analgesic effect of morphine in the tail-flick test lagged slightly behind morphine brain level in both species. In mice implanted s.c. with morphine pellets, significant analgesia and appreciable morphine brain levels appeared as early as 20 to 30 minutes after implantation. Increased brain morphine corresponded to increased analgesia at 1 and 4 hours after implantation. Tolerance was evident by 24 hours after implantation and was maximal at 72 hours. Brain morphine remained elevated up to 144 hours after implantation even though substantial encapsulation of the pellet occurred within 72 hours. If pellets were removed at 72 hours, brain morphine declined to control levels with 6 hours, but significant tolerance persisted for at least 24 hours after pellet removal. These results demonstrate that morphine is absorbed from the pellet up to 6 days after implantation and that the decreased analgesic activity observed in the latter times is due to tolerance to the narcotic and not to a decrease in absorption from the pellet.


Selective antagonism of the intesinal stimulatory effects of morphine by isoproterenol prostalglandin E1 and theophylline.

Contractions induced by graded intraaterial bolus doses of morphine and acetylcholine were measured in isolated segments of dog intestine perfused via the vasculature with Kreb's solution. Addition of the alpha and beta adrenergic receptor agonist, norepinephrine (0.2 mug/ml) to the perfusion solution decreased the magnitude of contractor responses to acetylcholine slightly and to morphine considerably. The pure alpha adrenergic receptor agonist, methoxamine (50 mug/ml), and the pure beta adrenergic receptor agonist, isoproterenol (5 mug/ml), produced similar effects; marked inhibition of responses to morphine and barely discernable inhibition of responses to acetylcholine. The mild inhibitory effects of these adrenergic amines on responses to acetylcholine are attributed to actions on neural and possibly non-neural adrenergic receptors. Perfusion of intestinal segments with Kreb's solution containing prostaglandin E1 (1 mug/ml) or theophylline (180 mug/ml) resulted in marked decreases in responses to morphine but had no significant effects on responses to acetylcholine. Patterns of inhibition similar to those seen with morphine have been observed previously with 5-hydroxytryptamine, which may mediate the intestinal stimulatory effects of morphine. Since isoproterenol, prostaglandin E1 and theophylline share in common the ability to elevate or maintain intracellular levels of cyclic adenosine monophosphate, the intestine stimulatory effects of morphine may result from 5-hydroxytryptamine-mediated interference with smooth muscle inhibitory actions of cyclic adenosine monophosphate.


Acetanilides: effects on invertebrate neurons correlated with analgesic activity in vertebrates.

Identified neurons in the buccal ganglion of the marine mollusc Navanax inermis were used to examine the effects of acetanilides on neuronal membrane properties. Acetanilides increased the membrane potential and conductance of these neurons in a dose-dependent, reversible manner. These events would have the effect of decreasing membrane excitability. Acetanilides increased the slope of the curve of membrane potential as a function of log [K+]o from 33 to 58 mV decade change in [k+]o and decreased the transient depolarization observed upon reducing [Cl]o. These results indicate that acetanilides increase membrane potential and conductance by increasing the potassium conductance of the membrane relative to the chloride conductance. The variation in membrane potential as a function of external alkali-cation concentrations was used an as indirect measure of alkali-cation permeability. Acetanilides altered the relative cation permeability from Rb (1.25) greater than K (1.0) greater than Cs (0.60) greater than NaequalsLi (0.07) to K (1.0) greater than Rb (0.71) greater than Cs (0.31) greater than NaequalsLi (0.00). This shift in relative cation permeability is interpreter, in terms of Eisenman's theory of membrane permselectivity, as indicating that acetanilides increase the anionic field strength of the membrane. The ability of acetanilides to increase membrane potential or alter permselectivity is directly correlated with octanol-water partition coefficient (r equals 0.96), indicating that hydrophobicity per se can account for almost all of the activity. Steric factors are unimportant. Analysis of published experiments on acetanilide analgesia in mice reveals that hydrophobicity can also account for much of the activity in that system. Results obtained in the molluscan system may thus provide insight into the ionic, biophysical and physicochemical mechanisms underlying acetanilide-induced analgesia.


The effects of harmaline on sodium transport in human erythrocytes: evidence in favor of action at interior sodium-sensitive sites.

The effects of the hallucinogen, harmaline (HME), and its congeners on human red blood cell (RBC) transport were studied. HME reduced sodium efflux by 70% at maximum inhibitory concentrations (6-8 mM). It acted upon the ouabain-sensitive component of sodium efflux since it exerted no inhibitory actions in the presence of ouabain. Several lines of evidence suggested that HME exerted its inhibitory effect at intracellular sodium-sensitive sites. The percent inhibition of Na efflux by 0.1 mM HME was unaffected by increasing extracellular potassium from 10 to 100 mM. When HME was incorporated into RBC ghosts by reversible hemolysis, the degree of inhibition of sodium efflux was comparable to that found with ouabain outside the red cells and was always greater than the inhibition produced with HME outside cells. HME increased membrane permeability to sodium, as shown by enhanced sodium influx into RBC and at concentrations of 10 mM caused rapid increments of intracellular sodium and decrements of intracellular potassium. We conclude that the harmala alkaloids inhibit the active Na-K transport system in human RBCs through their effects on sodium-sensitive transport sites on the interior membrane surface.


The renal vascular effects of meglumine diatrizoate.

Left ventricular injection of meglumine diatrizoate caused an initial (1-10 minute) decrease in renal vascular resistance followed by a late (30-minute) increase in renal vascular resistance. The late renal vasoconstrictor response was not blocked by bilateral cervical vagotomy, by renal adrenergic blockade or by renal alpha adrenergic receptor blockade; it was blocked by prior extracellular fluid volume expansion and blockade of the response of the kidney to angiotensin II. There was no effect on intrarenal distribution of blood flow. In the kidney perfused at constant flow, injections of meglumine diatrizoate into the kidney resulted in early renal vasodilation (1-5 minutes) with a return to control renal vascular resistance by 7 minutes; no vasoconstriction was observed. The renal vasodilatation was not abolished by prior treatment with atropine. Vasodilator responses identical to those observed with meglumine diatrizoate were obtained with 4.5% NaCl (equiosmolar to meglumine diatrizoate); no response was obtained with 0.9% NaCl. When given into either the left ventricle or the renal artery, meglumine diatrizoate caused an early reversible depression in renal extraction of para-aminohippurate; both 0.9 and 4.5% NaCl were without effect. The renal vasodilation produced by meglumine diatrizoate initially appears to be caused by its hyperosmotic properties; the late renal vasoconstrictor response appears to be mediated via an activation of the renin-angiotensin system. The depressive effect of meglumine diatrizoate on the renal extraction of para-aminohippurate is not related to its osmotic properties but rather to an effect of the organic iodinated molecule on cellular transport of para-aminohippurate.


Myocardial uptake of ouabain in intact dog and man.

The time corse of ouabain extraction from the coronary circulation was determined after single i.v. doses (3-H-labeled in the dogs). Plasma ouabain concentration ([O]) was measured in serial, paried arterial (A) and coronary sinus (CS) blood samples by radioimmunoassay in the patients and by 3-H-counting in the dogs. In both species, the difference in [O] between A and CS (A - CS [O]) narrowed rapidly during the initial 1 to 3 minutes and then at a slower rate in an exponential fashion the next 4 to 12 minutes, with a mean half-life of 2.6 plus or minus 0.4 (S.D.) minutes in the patient (n equals 6) and 1.4 plus or minus 0.5 minutes in the canine (n equals 10) studies. In four dogs, the A - CS concentration difference of sucrose (an extracellular fluid marker) was gone within 60 seconds after an i.v. bolus. In the canine studies, the exponential phase of ouabain removal from the coronary circulation accounted for 49 plus or minus 8% of that directly measured in left ventricular samples obtained shortly after ouabain uptake was complete (17.0 plus or minus 4.5 minutes after the i.v. dose). Left ventricular [O] in these samples was 11.6-fold higher than in simultaneously obtained plasma. Thus, the initial rapid efflux of ouabain, like sucrose, from the coronary circulation would appear toreflect movement into interstitial fluid, whereas the subsequent exponential removal of ouabain, occurring after equilibrium between plasma and intersitital fluid, reflects binding to myocardial cells.


Interaction of angiotensin with exogenous and neurally released norepinephrine on the cat nictitating membrane in vitro.

We have studied the effect of high (1-2.9 X 10(-5) M) and low 1.9 X 10(-9) M) concentrations of angiotensin on the retention and release of 3H-norepinephrine by the cat isolated nicititating membrane preparation in vitro in conjunction with their effect on the contractile responsiveness of the preparation to exogenous norepinephrine and transmural electrical stimulation. Both concentrations of angiotensin made the preparation contract, but only the high concentration affected the retention and spontaneous efflux of 3-H-norepinephrine. Retention was inhibited about 25% only when the preparation was preincubated with the angiotensin for 30 minutes (i.e., before adding 3H-norepinephrine). Under similar conditions cocaine, 2.9 X 10(-5) M, inhibited retention more than 90%. Spontaneous efflux was increased for as long as the high concentration of angiotensin was in contact with the preparation. Under similar conditions, tyramine, 5.7 X 10(-6) M, caused a much greater sustained increase in spontaneous efflux. Transmural stimulation of the preparation caused release of 3H-norepinephrine and frequency-dependent contractions. The contractions were selectively inhibited by phentolamine, 2.7 X 10(-6) M, or bretylium, 2.4 X 10(-5) M. Angiotensin had no effect on this neurally mediated 3H-norepinephrine release and contractile response or on contractions produced by exogenous norepinephrine. Since, as reported previously, angiotensin in vivo strongly inhibits contractile responses of the cat nicitating membrane to both neurally released and exogenous norepinephrine, the present results make it unlikely that such inhibition derives from angiotensin's relatively modest capacity for affecting the disposition of norepinephrine by this effector organ.


Pentobarbital pharmacokinetics in the normal and in the hepatectomized rat.

The pharmacokinetics of pentobarbital, a barbiturate metabolized by the liver, was compared in normal and in hepatectomized rats. The blood concentration time curve following a single intravenous injection of pentobarbital was fitted to a two-compartment open model. Both the volume of the central compartment and the elimination rate constant were significantly reduced in hepatectomized rats. It is concluded that the liver plays a role both in the metabolism and the distribution of pentobarbital.


Study of the hepatic metabolism of primidone by improved methodology.

The metabolism of the anticonvulsant drug primidone (PRM) was studied in the isolated perfused rat liver by a radiotracer methodology that permits nearly quantitative accounting of the dose as drug and identified metabolites. 14C-PRM and its metabolites were separated by thin-layer chromotography and quantitated by liquid-scintillation counting PRM was extensively converted to known active metabolites: phenobarbital (PB), 15%, and phenylethylmalonamide, 80%, in control livers during 120 minutes. Pretreatment of rats with PB greatly accelerated the rate of PRM metabolism, pretreatment with PRM only moderately so. There was no differential induction of the two metabolism pathways. Addition of phenylethylmalonamide to the perfusate reduced the rate of PRM metabolism but addition of PB did not. It is concluded that conversion of PRM to its active metabolites may be simultaneously influenced by the processes of metabolite induction (PB) and metabolite inhibition (phenylethylmalonamide).


A study of absorption of compounds from the rat biliary tree by retrograde intrabiliary injection (RII).

Absorption of compounds from the biliary tree of rats was studied by a retrograde intrabiliary injection (RII) technique. After RII of a number of compounds in volumes that exceeded the maximum distended capacity of the biliary tree, only that volume of RII solution which corresponded to biliary tree capacity remained therein. Furthermore, this latter portion of RII solution was absorbed by a first-order process when the duration of bile duct cannula occlusion was extended. Thus, the present study demonstrates that absorption of retrogradely injected compounds continues during occlusion. Since excretion of i.v. administered compounds into the biliary system was also shown to continue during occlusion, we propose in the present study a concept of bidirectional exchange of solute within the biliary tree during occlusion. As an additional finding, after RII and occlusion, a temporary increase in bile flow was obtained. If the occlusion duration was 3 minutes or less, the bile flow response was of sufficient magnitude to repay alomst exactly the volume of bile that would have been expected to be produced. If the occlusion was 6 and 9 minutes the increased magnitude of the bile flow response was not great enough to repary the larger bile volumes expected and underpayments of -48 and -96 mul were incurred.


Immunopharmacological studies using 5-hydroxytryptamine antibody.

An antibody to serotonin (5-HT) was tested on several preparations in which 5-HT is considered to be involved. The antibody was capable of effectively competing with 5-HT receptor sites for free molecules of 5-HT. It inhibited the uptake of 3H-5HT by blood platelets and may explain the reduced endogenous 5-HT concentration in blood platelets of immunized rabbits. The decreased platelet content of 5-HT was substantiated by electron microscopic studies which showed a reduction in the number of 5-HT-containing subcellular storage organelles in platelets from these animals. The 5-HT antibody inhibited the 5-HT-induced contraction of aortic strips in a tissue bath preparation. When given intraventricularly, it inhibited for a time the sedative actions of reserpine thus adding new evidence to the often postulated role of 5-HT in the actions of reserpine.


Mechanism of action of colchicine. II. Effects of colchicine and its analogs on phagocytosis and chemotaxis in vitro.

Colchicine, desacetylmethylcolchicine and colchiceine suppress the phagocytosis of starch granules by rabbit peritoneal polymorphonuclear leukocytes in vitro. Trimethylcolchicinic acid and 2-desmethylcolchicine glucoside have no effect on phagocytosis. Colchicine, at concentrations as high as 1 X 10(-4) M, has no effect on chemotaxis of polymorphonuclear leukocytes in response to immune complex-activated chemotactic factors or on the motility of these cells. These results do not support the contention that the suppression of phagocytosis or chemotaxis plays a significant role in the anti-inflammatory activity of colchicine.


Effects of sodium acetylsalicylate on body temperature of monkeys under heat exposure.

Exposure of Taiwan monkeys to 38 degrees C ambient temperature caused: a) raised body temperature, b) restlessness and struggling, c) increased evaporative heat loss and d) increase in tail skin temperature. After the administration of sodium acetylsalicylate, 100 to 250 mg/kg intraperitoneally or 4 to 15 mg intracerebroventricularly (third ventricle) the same heat load caused: a) less increase in body temperature, b) no restlessness or struggling, c) an initially higher rate of evaporative heat loss and d) higher tail skin temperature. Larger doses of acetylsalicylate caused greater antihyperthermic effects. Intracerebroventricular injection was more effective than the intraperitoneal route. These data show that acetylsalicylate improved tolerance of animals to external heat loads. The magnitude of body temperature elevation during heat exposure was reduced in the presence of acetylsalicylate by activation of heat-dissipating mechanisms, presumably through the central nervous system.


Effects of mercury on spermatogenesis studied by velocity sedimentation cell separation and serial mating.

Recently the potential toxicity of environmental mercury has become a major concern. Human tissues contain mercury due to daily environmental exposure. Nearly all of the mercury contaminating food is in the form of methylmercury complexes, due to the biotransformation of inorganic mercury. This report compares the reproductive effects of methylmercury hydroxide and mercuric chloride in male mice. The mercuric compounds were administered intraperitoneally once at a dose of 1 mg/kg (based on Hg++ concentration), or spermatogenic cells were exposed in vitro to Hg+ concentrations ranging from 10(-3) to 10(-8)M. Spermatogenic cells were separated for biochemical studies using the velocity sedimentation technique, and in vivo serial mating was used to assess fertility. The effects of CH3Hg+ or Hg++ on the uptake of 3H-thymidine by spermatogonia, 3H-uridine by early elongated spermatids, and 3H-L-leucine by late elongated spermatids were studied. These in vitro experiments indicated that at 1-(-3) m CH2HgOH reduced thymidine incorporation by spermatogonia by 40%, uridine incorporation by elongated spermatids by 39% and L-leucine incorporation by late elongated spermatids by 40%. Results obtained with HgCl2 were similar but of lesser magnitude. In vivo administration of CH3HgOH and HgCl2 significantly inhibited the uptake of thymidine, uridine and L-leucine by their respective spermatogenic cells. Fertility profiles obtained from serial mating studies indicated that the primary effect of CH3HgOH was on spermatogonial cells, premeiotic spermatocytes and early elongated spermatids, with no apparent effect on spermatozoa in testis, peididymis or vas deferentia. HgCl2 also primarily affected spermatogonial and premeiotic cells, but the effect was less than that seen with CH3HgOH. Statistical analysis indicated significant antifertility effects. Inhibition of uptake of thymidine and uridine was well correlated with the functionality of these cells as reflected in the fertility profile, excep for L-leucine uptake. Mercury ion-induced antifertility effects at the dosage used in these experiments are reversible. Thus, these results suggest spermatogenic effects of methylmercury complexes which might have important health consequences in man.


Comparison of aortic calcium and contractility in male, female and lactating female rats.

Catecholamine-induced vascular smooth muscle contration is enhanced in female animals and in presence of emale sex hormones in vitro. Androgens appear to depress these responses. Sex steroids may also alter calcium ion (Ca++) binding and metabolism. We compared contractility as well as quantity and relative lability of tissue calcium pools in male and female rat isolated aortic strips bathed in Ca++-free solution. We also studied aortic strips from 21-day postpartum lactating female rats to determine the effects of previous high circulating levels of female sex steroids (present during pregnancy) and prolactin (present during lactation). Rat aortic strips were found to contain loosely and more tightly held calcium stores. Strips from males were unresponsive in Ca++-free solution unless previously exposed to a Ca++-rich bathing medium. They accumulated more tissue calcium when bathed in Ca++-rich solution than did strips from females. This extra calcium appears to reside in the loosely-held fraction. Tissues from males first incubated in Ca++-rich solution to enhance the loosely held fraction respond more readily in Ca++-free solution to a high potassium (K+) concentration than to epinephrine. Strips from females respond about equally to high K+ or epinephrine whereas aorta from lactating female rats are much more responsive to epinephrine in Ca++-free solution and gain less calcium in Ca++-rich medium than those of the other rats. These data suggest that in the presence of high circulating levels of female sex hormones or other female factors (e.g., prolactin) enhanced binding or sequestration of potential activator ions occurs which increases the responsiveness of the tissue to catecholamines. Male sex hormones and/or factors promote the capacity of the rat aorta to gain a more loosely held calcium fraction which is readily used for contraction by K+ depolarization.


Comparative antihypertensive effects and tissue distribution of beta adrenergic blocking drugs.

The precise mechanism of the antihypertensive action of beta adrenergic blocking drugs is not known. Both peripheral and central sites of action have been proposed. The comparative antihypertensive actions and tissue distribution of propranolol, pindolol and sotalol were investigated in both normotensive Sprague-Dawley and spontaneously hypertensive rats. From recordings of concurrent changes in blood pressure and heart rate it was observed that oral or subcutaneous administrations of both propranolol and pindolol, but not sotalol, consistently reduced blood pressure and heart rate. Tissue distribution of all three agents was determined after 14 days of treatment. Propranolol and a metabolite were concentrated in the hippocampus whereas pindolol was concentrated in the septum. Significant central concentrations of sotalol were not demonstrable. All three agents produced persistent peripheral beta adrenergic blockade. It is concluded that beta adrenergic blockade may not be the important mechanism of the antihypertensive action of beta adrenergic blocking drugs. A modification of central autonomic control mechanisms is proposed as a possible mechanism of action.


Effects of dimethyl quaternary propranolol (UM-272) on oxygen consumption and ischemic ST segment changes in the canine heart.

The effect of dimethyl quarternary propranolol, UM-272, on myocardial oxygen consumption was determined experimentally in anesthetized, open-chest dogs in which the left anterior descending and circumflex coronary arteries were cannulated and perfused at a constant pressure. Coronary arterial and venous blood samples were collected and their oxygen content were measured. Myocardial oxygen consumption was calculated and expressed as milliliters per minute per 100 grams of left ventricle. Mean control myocardial oxygen consumption in five animals was 11.7 +/- 1.9. This was significantly reduced to 7.6 +/- 1.1 after UM-272, 10 mg/kg (P less than 0.5). In separate experiments, hearts were excised from anesthetized dogs and were perfused with oxygenated whole blood via the aorta. Coronary blood flow was held constant and oxygen consumption was calculated and expressed as milliliters per minute per 100 g of myocardium. Mean control oxygen consumption in five hearts was significantly reduced from 3.1 +/- 0.2 to 2.1 +/- 0.1 (P less than 0.01). In addition, the effect of UM-272 on myocardial ischemic injury produced in response to acute coronary artery ligation was assessed. The sum ST segment elevations from six epicardial recording sites was reduced from 34.8 +/- 4.9 to 11.3 +/- 2.1 mV (P less than .05). These data suggest that UM-272 would aid in ischemic heart disease by reducing both oxygen utilization and ischemic damage. These data, although suggestive, do not exclude other mechanisms as being related to the reduction in ST segment elevation, mechanisms which may not involve a reduction in myocardial oxygen consumption.


Ouabain-induced changes in electrophysiologic properties of neonatal, young and adult canine cardiac Purkinje Fibers.

Young patients frequently require higher concentrations of digitalis per kilogram of body weight or per square meter of surface area than adults to induce digitalis effect or toxicity. In order to investigate the electrophysiologic basis for this observation, we used standard microelectrode techniques to study the effects of ouabain on action potential characteristics of cardiac Purkinje fibers of neonatal (1-7 day), 4 to 7 week and adult dogs. Purkinje fibers were stimulated at a 500-msec cycle length. Action potentials were recorded during control Tyrode's perfusion and 23.5 minutes after onset of superfusion with ouabain, 2 X 10(-7) M (10% ouabain-3H). The Purkinje fibers were then assayed for ouabain uptake. Ouabain accelerated repolarization and decreased action potential amplitude, resting membrane potential and maximum upstroke velocity of phase O. Changes were greatest in the adults, least in the neonates. Ouabain increased the slope of phase 4 depolarization in 10 to 12 adults, 7 of 16- 4 to 7-week puppies and 0 of 12 neonates. Hence, ouabain induced lesser changes in the action potentials of Purkinje fibers taken from young animals. These results suggest that Purkinje fiber sensitivity to ouabain effects increases with age.


The cardiac pharmacology of tolbutamide.

Recent clinical studies have suggested an association of tolbutamide therapy with an increased incidence of cardiovascular deaths. Due to the paucity of information concerning the acute cardiac actions of tolbutamide, the effects of this agent upon cardiac contractility and automaticity were examined under in vivo and in vitro conditions in rabbit, cat and dog heart muscle preparations. Tolbutamide (10(-6) to 3 x 10(-3) M) produced a biphasic inotropic response with a peak positive inotropic response at 3 X 10(-3) M which was 13.7 +/- 5.1% of the maximal obtainable increase in tension. Similar studies in cat papillary muscle resulted in a response that averaged 19% of the maximal increase in contractile force. In contrast, canine papillary muscles as well as the intact canine heart failed to develop a positive inotropic response to tolbutamide. Responses of rabbit atrial strips to isoproterenol were not potentiated by previous exposure to tolbutamide. Exposure of rabbit atria to theophylline, 2.5 X 10(-4) M, did not potentiate the inotropic effects of tolbutamide. Stidies in spontaneously beating rabbit right atria and cat papillary muscle-Purkinje fiber preparations demonstrated that tolbutamide does not have the potential to augment automaticity in these tissues. In intact dog heart, the intracoronary administration of tolbutamide did not lead to disturbances in cardiac rhythm, providing additional evidence that tolbutamide does not increase ventricular automaticity. It is concluded that tolbutamide possess a species-specific positive inotropic effect in rabbit and cat but not in the dog. The inotropic effect is small when compared to the maximum inotropic response and is observed only in vitro. Tolbutamide lacks the ability to enhance cardiac pacemaker activity. These data do not support the conclusions of previous investigatirs concerning the possible deleterious cardiac effects of tolbutamide.


Amphetamine: evaluation of d- and l-isomers as releasing agents and uptake inhibitors for 3H-dopamine and 3H-norepinephrine in slices of rat neostriatum and cerebral cortex.

Release of 3H-doapamine or of 3H-norepinephrine and inhibition of accumulation of 3H-dopamine or 3H-norepinephrine by d- and l-amphetamine were studied in slices of rat neostriatum and in slices of rat cerebral cortex. The two stereoisomers of amphetamine were equally potent as inhibitors of accumulation in the cortex, whereas d-amphetamine was approximately 3-fold more potent than l-amphetamine in the neostriatum. A similar relationship was observed between the two stereoisomers in release experiments. Some spontaneous efflux of 3H-dopamine from tissue slices was evident in absence of added drug in release experiments. When cocaine (2 X 10(-5) M), a known inhibitor of biogenic amine uptake, was added to the medium, there was very little increment in spontaneous efflux of 3H-dopamine in neostriatal slices, but cocaine blocked the release caused by d-amphetamine. This showed that the apparent releasing action of d-amphetamine in the neostriatum was not due to blockade of reuptake of spontaneously released material and that d-amphetamine itself must be taken up to evoke a releasing action. Experiments were designed to compare directly the releasing and uptake inhibiting actions of d-amphetamine. In the cortex, uptake inhibition of 3H-norepinephrine was greater than release over a wide concentration range, while in the neostriatum the two actions were essentially identical in magnitude for 3H-dopamine. We conclude that in the cortex, d-amphetamine can act both to release and to block uptake of 3H-norepinephrine. In the neostriatum, on the other hand, there is releasing action of 3H-dopamine by d-amphetamine (which is stronger than that in the cortex), but the apparent blockade of "uptake" is of questionable significance and appears to result from the release of previously accumulated 3H-dopamine


Application of principles of steady-state kinetics to the estimation of brain acetylcholine turnover rate: effects of oxotremorine and physostigmine.

We have measured the turnover rate of acetylcholine (ACh) in the brains of mice injected with doses of oxotremorine and physostigmine that cause a prolonged increase of ACh concentration in brain. The method used to measure turnover rate of ACh is an application of principles of steady-state kinetics to the change with time of brain choline (Ch) and ACh specific radioactivities after an intravenous pulse injection of phosphorylcholine. We have found that when the concentration of brain ACh and Ch is increased to a new steady state as a result of oxotremorine and physostigmine injections the turnover rate of brain ACh decreases from 0.34 mumol/g/hr (in saline-treated mice) to 0.12 and 0.061 mumol/g/hr, respectively. The possibility that an increase of brain Ch or ACh concentrations plays a role in the control of brain ACh turnover rate is discussed.


The transport of gentamicin in the choroid plexus and cerebrospinal fluid.

Gentamicin often attains inadequate therapeutic levels in cerebrospinal fluid (CSF). In the present study, the possibility that gentamicin might be transported from CSF to blood by a mechanism in the choroid plexus was investigated. Rabbit choroid plexuses were incubated 15 to 120 minutes in artificial CSF containing 14C-gentamicin and 3H-inulin. The choroid plexuses accumulated gentamicin linearly up to 120 minutes where a tissue/medium ratio of 5.4 was attained. Uptake of gentamicin was inhibited by: 1) increasing the gentamicin concentration or adding kanamycin; 2) omitting oxygen and glucose; 3) adding dinitrophenol to the medium; 4) incubating at 4 degrees C; OR 5) incubating in rabbit CSF. However, uptake was not inhibited by probenecid or ammonium ion. Kinetic analysis revealed that gentamicin was transported into choroid plexus by a process that satisfied Michaelis-Menten kinetics. A Lineweaver-Burk transformation of the transport values for the saturable component yielded a Kt of 51.8 mug/ml and a Vmax = 1.8 mug/ml/min. In vivo, gentamicin clearance from CSF, although saturable, was only 1.4 times greater than inulin because of the relatively low Kt and Vmax of the choroid plexus transport system for gentamicin and the presence of inhibitors of gentamicin transport in rabbit CSF. We conclude that the saturable transport of gentamicin from CSF, although quantitatively not large, is a factor in determining gentamicin levels in CSF.


Permeability of selected drugs and chemicals across the blood-testis barrier of the rat.

Physiological studies by Setchell and others have described the existence of a blood-testis barrier (BTB) surrounding the seminiferous tubules of the mammalian testis. These studies were initiated to better define the role of the BTB with regard to the penetration of exogenous chemicals to male germ cells. The rete testis was cannulated in rats and fluid was collected. Test chemicals or drugs were usually administered by continuous i.v. infusion. Permeability of nonelectrolytes of various molecular sizes, acidic compounds with varying partition coefficients and pKalpha values, such as salicylic acid, barbiturates, and sulfonamides, across the BTB were studied. Permeability of nonelectrolytes was demonstrated to be dependent upon their molecular size, suggesting bulk flow through water-filled pores. On the other hand, permeability of acidic drugs with varying pKalpha values depended upon their partition coefficients. Transport of these chemicals from blood to seminferous tubules closely resembled their transport from blood to cerebrospinal fluid. It appears that the BTB is a complex multicellular system composed of membranes surrounding the semiferous tubules and the several layers of spermatogenic cells organized within the tubules, which restrict the permeability to the male germ cells of many foreign compounds. This must be borne in mind when extra-polating data from in vitro mutagenic test systems to man.


Interactions of tricyclic antidepressants and barbiturates in barbiturate-tolerant and nontolerant rats.

Pretreatment of rats with tricyclic antidepressants, imipramine, desipramine, amitriptyline and nortriptyline, at two doses (5 and 25 mg/kg) 20 minutes before administration of barbiturate markedly reduced the latent period of the response to barbital and prolonged the sleeping time induced by pentobarbital (PB) and barbital. The effects were dose-dependent. The prolonged sleeping time produced by PB was associated with decreases in the rates of disappearance of PB from the brain and plasma. The effect of tricyclic antidepressants on PB hypnosis in PB-tolerant and nontolerant rats was apparently not related to change in central nervous system (CNS) sensitivity to PB, since at the time of awakening there were no significant differences in the concentrations of unmetabolized PB in either the plasma or brain of tricyclic antidepressant-treated animals as compared to controls. As barbital is not metabolized, potentiation of barbital hypnosis by tricyclic antidepressants must be attributable to a direct effect on CNS rather than on liver microsomal enzymes. Direct evidence was provided by the findings that amitriptyline accelerated the brain uptake of barbital and that amitriptyline-treated animals lost and recovered the righting reflex at brain barbital levels lower than those of controls. Rats made tolerant to the hypnotic effect of barbital also became tolerant, in varying degrees, to the hyposis-prolonging properties of tricyclic antidepressants. It is concluded that tricyclic antidepressants prolong PB sleeping time in PB-tolerant and nontolerant rats by inhibiting its biotransformation in the liver. The action of tricyclic antidepressants to prolong the hypnotic action of barbital in normal rats is related to their direct effects on CNS sensitivity to barbital, but such effects are makedly diminished after animals become tolerant to barbital.


Depletion of S-adenosyl-L-methionine in mouse brain by antidepressive drugs.

A sensitive enzymatic-isotopic method based on the methylation of histamine by histamine methyltransferase has been used to measure the endogenous concentration of S-adenosyl-L-methionine in mouse brain. After a single dose of imipramine, DL-dopa, pargyline or d-amphetamine, brain S-adenosyl-L-methionine levels were 50% depleted after 1 hour, but had returned to normal values within 4 hours after drug treatment. A similar but long-lasting depletion of S-adenosyl-L-methionine was obtained after chronic treatment with imipramine or after a single dose of cycloleucine, a drug that interferes with the synthesis of S-adenosyl-L-methionine from methionine. The rate of methylation of 3H-norepinephrine given by intraventricular injection suggested that the decreased levels of S-adenosyl-L-methionine after the administration of cycloleucine and after the chronic, but not the acute, administration of imipramine may interfere with the inactivation of norepinephrine in the mouse brain. These results indicate that decreased methylation may contribute to the neurochemical effects of antidepressive drugs.


Effects of d-amphetamine on the behavior of pigeons maintained by a second-order schedule of reinforcement.

The effects of various doses of d-amphetamine were studied on the responding of two pigeons exposed to a second-order schedule of reinforcement. With this schedule, food was presented following the completion of a sequence of three 2-minute fixed-interval components. A visual stimulus was presented at the completion of each fixed interval, including the one which was terminated with food. The pigeons' behavior was characterized by a pause immediately after each stimulus presentation followed by a gradual increase in response rate as the interval progressed. d-Amphetamine was found to increase the low rates of responding which occurred early in each interval and to decrease the high rates of responding at the end of each interval. These effects occurred whether responding preceded the presentation of food or the brief stimulus alone.


Separating the effects of response rate and reinforcement frequency in the rate-dependent effects of amphetamine and scopolamine on the schedule-controlled performance of rats and pigeons.

Rats and pigeons responded under three-component multiple schedules of food reinforcement. Each component was associated with a separate stimulus condition and a schedule that arranged food delivery intermittently for appropriately spaced responding. In the experiment with pigeons, three response rates were maintained with equal reinforcement frequency in the three components. With rats, the lowest response rate was associated with a higher reinforcement frequency. The effects of d-amphetamine in rats (0.05-0.6 mg) and pigeons (0.1-3.0 mg) were closely associated with the dose, and with the response rates that occurred under nondrug control conditions. Small doses of d-amphetamine increased low response rates proportionately more than moderate rates; moderate rates were increased proportionately more than were high rates. With larger doses, low rates were decreased proportionately less than were moderate rates, which in turn were decreased proportionately less than were high rates. Similar relations between drug effects and control rates were obtained in rats with scopolamine (0.0125-0.4 mg), with the exception that constant effects appeared at doses of 0.1 mg and greater. The present experiments, through manipulating response rate independently of reinforcement frequency, show that the rate-dependent effects of d-amphetamine and scopolamine are primarily response-rate-dependent drug effects.


Rate-dependent effects of drugs on the variable-interval behavior of rats.

Three rats were exposed to a variable-interval (VI) schedule of food reinforcement and three were exposed to the same VI schedule but with the added constraint that reinforcement could follow only a response which occurred at least 5 seconds after the preceding response. The rats exposed to this pacing requirement responded at considerably lower rates, but obtained only slightly fewer reinforcers than those exposed to the simple VI schedule. The effects of d-amphetamine were found to be dependent on the schedule which maintained behavior. This drug produced a dose-related decrease in rates of responding maintained by the unpaced VI schedule but a dose-related increase in the much lower rates maintained by the paced VI schedule. The effects of chlordiazepoxide were not so clearly schedule-dependent although there were some differences between the effects of this drug on responding maintained by the two schedules. These results support the view that the effects of d-amphetamine depend critically on the rate of the response under investigation, but this does not appear to be the case for chlordiazepoxide.


Presynaptic effects of neuromuscular cholinesterase inhibition.

Paraoxon, an irreversible organophosphorus inhibitor of cholinesterase, produces a myopathy beginning at the neuromuscular junction in rat diaphragm muscles. Thirty minutes after paraoxon was injected i.p. (0.5 mg/kg), neuromuscular cholinesterase activity was reduced to 36% of control. The frequency of miniature end-plate potentials (MEPPs) in diaphragms from paraoxon-treated rats was 109/sec compared with 2.9/sec in saline-injected controls. The faster frequency was seen after paraoxon gradually declined to control rates within 6 hours after injection. The quantum content of end-plate potentials was reduced to 66% of that seen in saline controls. Spontaneous and impulse-related antidromic activity was observed along the phrenic nerve after paraoxon which also gradually diminished with time. When the phosphorylated acetylcholinesterase was reactivated with 10(-3) pyridine-2-aldoxime methiodide, MEPP frequency was reduced significantly and antidromic activity was abolished. Block of axonal excitability with 10(-6) M tetrodotoxin reduces the effects of paraoxon on MEPP frequency and antidromic activity, while acetylcholinesterase remains inhibited. In vitro perfusion with 6 times 10(-8) M paraoxon increases MEPP frequency and initiates antidromic activity. It is concluded that inhibition of neuromuscular cholinesterase by paraoxon leads to an alteration of transmitter release, and this may be associated with ultrastructural abnormalities observed at the motor endplate.


Abnormal secretory response to parasympathomimetic and sympathomimetic stimulations from the submaxillary gland of rats treated with reserpine.

Rats treated with 0.5 mg/kg of reserpine per day for 7 days were anesthetized and submaxillary saliva was collected and analyzed for Na+, K+, Ca++ and protein concentrations. Salivary secretion was elicited by i.p. injections of carbamylcholine (50-100 mug/kg), phenylephrine (5 mg/kg) and isoproterenol (10 mg/rat). Saliva was also collected from untreated controls. Submaxillary glands were excised from both groups of animals at the termination of the secretory response, homogenized and analyzed. Glands from other animals were removed in the resting state and similarly processed. Pretreatment with reserpine resulted in decreased volumes of salvia and in elevated salivary concentrations of Ca++ and protein. Saliva from the reserpine-treated animals secreted in response to carbamylcholine had higher concentrations of Na+ and K+ than control saliva, particularly at the low rates of flow. Saliva secreted after stimulation with the two sympathomimetic secretagogues had lower concentrations of these two ions. Resting glands from the treated animals showed significant elevations in protein and Ca++ content and a significant decrease in K+ content. At the end of the secretory response to the three secretagogues, glands from treated animals showed a significantly higher Na+ content and a significantly lower K+ content than control glands. It is concluded that pretreatment with reserpine alters the secretory response of the rat submaxillary gland to both parasympathomimetic and sympathomimetic stimulation. This alteration results from a toxic lesion caused by reserpine in the salivary cells, which involves changes in their permeability to ions and in their energy resources. These in turn, result in an abnormal stimulus-secretion coupling mechanism. The possibility that the toxic lesion is related to alterations in Ca++ homeostasis is discussed.


Effects of ketamine on left ventricular performance.

The cariac response to anesthetic doses of ketamine hydrochloride was studied in dogs, initially in the absence of other drugs and subsequently during beta adrenergic block with propranolol and combined beta adrenergic and cholinergic blockade with propranolol and atropine. Ketamine (4 mg/kg) was injected into the left atrium or the jugular vein. Administration of ketamine alone resulted in increases in heart rate (61 beats/min, P smaller than .001), cardiac output and left ventricular systolic pressure, but left ventricular end-diastolic pressure and dP/dt max (maximum rate of change of left ventricular isovolumic pressure development) were unchanged. After propranolol, the increase in heart rate produced by ketamine was attenuated, and a transient fall in dP/dt max occurred. After propranolol and atropine, heart rate was not changed by ketamine, but dP/dt max fell and left ventricular end-diastolic pressure rose. Systemic vascular resistance was not altered by ketamine. It is concluded that administration of ketamine increases sympathetic discharge and reduces vagal discharge to the heart. In the absence of sympathetic and vegal control over the heart, the drug depresses myocardial contractility.


The antiarrhythmic and hemodynamic actions of alpha, alpha-dimethyl-4-(alpha, alpha, beta, beta-tetrafluorophenethyl) benzylamine (MK-251).

Alpha,alpha-Dimethyl-4-(alpha,alpha,beta,beta-tetrafluorophenethyl)benzylamine (MK-251) has been found to prevent certain types of experimentally induced ventricular arrhythmias and at maximally effective doses possesses substantial hemodynamic safety in contrast to standard antiarrhythmic agents. MK-251 prevented or modified ventricular arrhythmias produced by injection of tetrafluorohexachlorobutane into the coronary artery of dogs and baboons. In dogs, the dose estimated to prevent 80% of the arrhythmic impulses (ED80) was 0.5 mg/kg i.v. and 5.0 mg/kg p.o. The duration of action after oral administration of 5.0 mg/kg to the dog or baboon exceeded 5 to 6 hours. MK-251 delayed the onset of arrhythmias resulting from coronary artery ligation, reduced their severity and permitted a conversion back to normal sinus rhythm earlier than in control dogs. In cats, the doses of digoxin required to induce ventricular ectopic activity, ventricular tachycardia and ventricular fibrillation were elevated by MK-251. In anesthetized dogs, 4 times the i.v. ED80 produced no change in blood pressure, cardiac contractility or output, or in ventricular conduction. The only effect after 8 times the ED80 was a slight decrease in contractility. In contrast. lidocaine at its ED80 (0.21 mg/kg/min), decreased blood pressure and contractility; there was no change in ventricular conduction. Quinidine at the ED80 (8.8 mg/kg i.v.) and above produced hypotension, decreased contractility and prolonged conduction in a dose-related manner.


Antiarrhythmic and antifibrillatory properties of aprindine.

The effectiveness of aprindine, N-[3-(diethyl amino)propyl]-N-phenyl-2-indanamine, was examined against experimentally induced arrhythmias. Ouabain-induced ventricular tachycardia was reversed in six of six dogs by aprindine, 5 mg/kg i.v. The threshold for extrasytoles induced by a 250-msec train of 60 Hz 2-msec pulses starting 75 msec after the pacing pulse was elevated from a control value of 0.18 +/- mA to a peak of 0.29 +/- 0.03 mA 5 minutes after aprindine, 5 mg/kg (P less than .005). The similarly determined ventricular fibrillation threshold was increased from a control value of 2.45 +/- 0.78 mA to a maximum of 5.68 +/- 1.47 mA 30 minutes after aprindine, 5 mg/kg i.v. (P less than .025). Aprindine failed to protect against fibrillation associated with one-stage occlusion and release of the left anterior descending coronary artery. Conscious dogs 24 hours after two-stage ligation of the left anterior descending coronary artery showed ectopic beats averaging 107 +/- 5 beats/min. Aprindine, 5 mg/kg i.v., caused an initial reduction of the ectopic rate to 1 +/- 1 beats/min (P less than .001) returning to 57 +/- 19 beats/min (P less than .05) 30 minutes postdrug. An additional 5 mg/kg dose reduced the ectopic rate to 1 +/- 1 beats/min (P less than .001) returning to 15 +/- 8 beats/min (P less than .005) 60 minutes after drug. Evaluation of these animals at 48 hours showed a similar pattern, although one animal fibrillated after 5 mg/kg of aprindine. Aprindine is an effective antiarrhythmic agent in some experimental cardiac arrhythmias, but the appearance of central nervous system toxicity at therapeutic drug concentrations in conscious animals indicates that it may have a narrow margin of safety.


Pharmacology of a potent, new antithrombotic agent, 6-methyl-1,2,3,5-tetrahydroimidazo[2, 1-b] quinazolin-2-one hydrochloride monohydrate.

The effect of 6-methyl-1,2,3,5-tetrahydroimidazo[2,1-b] quinazolin-2-one hydrochloride monohydrate (BL-3459) on platelet function and experimental thrombosis was evaluated in a series of in vitro, ex vivo and in vivo animal experiments. Potent inhibition of platelet aggregation for BL-3459 was demonstrated by both in vitro and ex vivo techniques. In vitro, EC50 levels were less than 1 mug/ml regardless of the aggregating substance used or the species of animal from which platelet-rich plasma was obtained. After oral administration to rats and dogs, BL-3459 was rapidly absorbed and had a long duration of action. Ex vivo ED50 values were in the range of 2 to 3 mg/kg p.o. In addition, BL-3459 (1-10 mg/kg) demonstrated significant oral activity in a variety of in vivo animal models. BL-3459 inhibited elevation in screen filtration pressure induced by hemorrhage in dogs, endotoxemic death in rats, intravascular thrombosis produced by electrical stimulation of the carotid artery of the dog and thrombosis induced by means of a biolaser in the microvasculature of the rabbit ear chamber. In contrast to acetylsalicylic acid, BL-3459 had little effect on bleeding time in guinea pigs. Oral or intraduodenal administration of BL-3459 to dogs lowered aortic blood pressure, stroke volume and peripheral vascular resistance, while elevating cardiac rate and cardiac contractile force. Thus, it had little effect on the estimated cardiac output. These cardiovascular effects were mediated, in large part, through direct-acting mechanisms. BL-3459 exhibited weak antiserotonin activity in isolated smooth muscle preparations. While the precise mechanism of action of BL-3459 has not yet been determined, indications are that the compound may prove useful in the prevention of intravascular thrombosis.


Potassium prorenoate: a new steroidal aldosterone antagonist.

Potassium prorenoate (SC-23992) is a water-soluble steroidal compound with the ability to antagonize the sodium-retaining and, when apparent, the potassium-dissipating effects of mineralocorticoids. A significant natriuretic response was obtained at dosages of 1 mg/kg and approximately 1.8 mg/kg in the dog and rat, respectively. Based upon an elevation in the previously depressed urinary log Na/K ratio, prorenoate possesses an oral potency of 4.6 and 8.1 times that of spironolactone (S), respectively, in the aldosterone and deoxycorticosterone acetate-treated adrenalectomized rat. In the aldosterone-treated dog, the compound had 3.0 times the potency of S and 2.2 times that of a related steroid, potassium canrenoate (SC-14266). Prorenoate and S are relatively inactive at the renal level in adrenalectomized rats without mineralocorticoid replacement. Prorenoate possesses no more than 2% of the natriuretic activity of hydrochlorothiazide in the intact animal. Clearance studies in dogs indicate a direct renal tubular site of interaction between prorenoate and aldosterone independent of changes in renal hemodynamics. The natriuretic response occurred within 100 minutes after a single oral dose and was sustained for at least 7 hours. Prorenoate possesses the pharmacological characteristics of an aldosterone antagonist, in common with those of S.


An enzymatic method (phospholipase B) for studies on cestode infection (Hymenolepis nana) and its suppression by chemotherapy.

The phospholipase B activity of the small intestine of mice infected with Hymenolepis nana has been studied to determine its value as a laboratory test for the presence of parasites and the chemotherapeutic effects of antitapeworm drugs. Mice infected with 500 H. nana eggs were examined on the 21st day of infection and the phospholipase B content of homogenates of small intestine was determined using lysolecithin (6.6 x 10(-3) M) as the substrate. Some of the infected animals were treated with niclosamide according to schedules and doses known to affect worm development. Presence or absence of parasites was verified by visual inspection of the intestinal content. The enzymatic and visual methods gave equivalent results in both infected-not treated and infected-treated groups. Special features of niclosamide action (relative refractoriness of the early parasitic forms, enhanced effect of multiple doses) have been confirmed. The enzymatic method is proposed as a procedure for laboratory testing in chemotherapeutic investigations.


Hepatic microsomal ethanol-oxidizing system (MEOS): dissociation from reduced nicotinamide adenine dinucleotide phosphate oxidase and possible role of form I of cytochrome P-450.

The activity of the hepatic microsomal ethanol-oxidizing system (MEOS) was compared with the content of three forms of cytochrome P-450. Measurements were also made of the activity of microsomal reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, the enzyme which generates H2O2 in microsomes and which has been considered by some to be the rate-limiting step of MEOS activity. Ethanol feeding to rats for 4 to 5 weeks significantly enhanced the activities of MEOS and NADPH oxidase by 102 and 62%, respectively. Concomitantly, form I of cytochrome P-450 was increased by 88% (P less than .001). Acute administration of a large dose of ethanol to animals pretreated chronically with ethanol enhanced MEOS activity by 21% (P less than .05), whereas NADPH oxidase activity remained unchanged. In addition, an acute dose of ethanol enhanced form I of cytochrome P-450 by 20% (P less than .05); thus its increase was comparable to that of MEOS activity. Pretreatment of rats with phenobarbital increased the specific activity of microsomal NADPH oxidase by 40% (P less than .05) but not that of MEOS. By contrast, CCl4 administration to rats diminished MEOS activity by 33% (P less than .01), whereas NADPH oxidase activity remained unchanged. The CCl4 treatment was found to decrease significantly all three forms of cytochrome P-450: form I by 45%, form II by 56% and form III by 24%. These results suggest that in the presence of NADPH microsomes oxidize ethanol to acetaldehyde by a process which involves, at least in part, the form I of cytochrome P-450 and in which H2O2 generation by NADPH oxidase is not the rate-limiting step.


The distribution time of intravenously injected raffinose and inulin in intact animals and the effect thereon of sex and infusion of oxytocin.

1. In anaesthetized dogs whose renal pedicles were ligated the distribution time for I.V. administered raffinose was noted. In males the plasma concentration of raffinose fell for 7-10 min from the time of injection and in females it fell for 12-15 min; thereafter in both sexes the plasma concentration remained constant. 2. During I.V. infusion of oxytocin 10 mug/kg. min, the distribution time for raffinose was 12-16 min in males and 4-6 min in females. 3. During the period before stabilization of plasma concentration the concentration of raffinose was higher in the femoral artery than in the vein in both sexes. 4. In anaesthetized rats whose renal pedicles were ligated the distribution time for I.V. injected inulin was 7-8 min in males and 5 min in females. 5. Following alpha-adrenoceptor blockade with phentolamine the distribution time in both male and female rats was 14-15 min. 6. The sex differences in distribution time, both in normal and oxytocin-treated dogs, may be related to the state of contraction and differential sensitivity or pre- and post-capillary blood vessels and hence, of capillary pressure.


The detection of gratings by independent activation of line detectors.

1. The visibility of composite stimuli (double lines, multiple lines and sinusoidal gratings) is analysed in terms of the visibility of single lines. 2. The detection mechanisms for the composite stimuli were examined by measuring the probabilities for seeing these stimuli, the probabilites of "recognition" near their detection thresholds and by using the method of subthreshold summation. 3. The simplest composite stimulus consists of two lines spaced apart by 15 min; it was found that both the probability of seeing this stimulus and the probability of reporting either one or two lines may largely be explained by assuming independent detection of the two lines. For a 12 min spacing some antagonistic interaction was observed between the two lines, confirming the existence of an antagonistic surround in the line detector. 4. The probability of seeing a multiple line target (rectangular grating) of spacing 15 min is slightly greater than that predicted assuming independent detection of its component lines; this probability can be calculated from the probabilities of seeing a central line (near the fixation point) and pairs of lines spaced 15, 30, 45, 60, 75 and 90 min on either side of the fixation point. The observed threshold for the grating was about 0.05 log units less than the prediction. 5. The probability that a subject reports only one line from a rectangular grating was found to be consistent with independent detection of its component lines when the subject used a low (detection) threshold criterion but not for higher criteria. 6. The spatial frequencies involved in the detection of the rectangular grating were determined by subthreshold summation; the high spatial frequency selectivity was shown to be consistent with independent detection of the component lines. 7. The detection mechanism for a 4 c/deg sinusoidal grating was found to be similar to that for the 15 min rectangular grating. 8. Evidence is presented that the detection of finer and coarser gratings may be analysed in similar terms. 9. It is shown that lines are not detected by independent activation of sharply tuned grating detectors but that sub-units may be involved which are slightly more narrowly tuned than the line detector. 10. These sub-units contain both inhibitory and disinhibitory regions; the disinhibitory responses may be the basis of the deviations from probability summation noted  in 4. 11. The properties of the proposed sub-units are in reasonable accord with the results of adaptation experiments.