Renal vein renin measurements in normotensive children.

Renal venous PRA was measured in 49 normotensive children without renal disease undergoing routine cardiac catheterization. PRA levels did not differ significantly between both renal veins and were significantly higher in the renal veins than in the IVC. There was a constant mean ratio of 1.21 between the renal veins and the IVC at low, intermediate, and high absolute PRA levels. Three patients had a renal venous PRA ratio greater than 1.4 and the highest ratio observed was 1.55. This fidning supports 1.5 as an acceptable upper limit of normality for the interpretation of renal vein PRA ratios in the investigation of patients with suspected renal hypertension. In four patients, PRA in the renal veins was significantly lower than in the IVC. The possibility of renin removal by these kidneys is discussed.


Bronchial artery embolization in cystic fibrosis; technique and long-term results.

Severe bronchial hemorrhage in 13 patients with cystic fibrosis was treated by catheter embolization of bronchial arteries. Indications were either excessive bleeding persisting for several days, or bleeding serious enough to interfere with pulmonary drainage and recurring over weeks or months. In follow-up ranging from one to 30 months, cessation of major bleeding was achieved in 12 of 13 patients (93%), although 5 of 13 patients (40%) did have recurrence of minor hemoptysis. No neurologic or other major complications were encountered. However, there are potential risks and this approach at present should be limited to patients with life-threatening bleeding and carried out only by experienced angiographers.


Postaxial acrofacial dysostosis syndrome.

Three patients with a postaxial acrofacial syndrome are presented; the features of these and three other previously described examples are set forth. The facies can be strikingly similar to that of the Treacher Collins syndrome. The limb deficiencies are postaxial, with absence or incomplete development of the fifth digital rays in both the upper and lower limbs. Accessory nipples have been found in most of the patients. The nature of the limb deficiencies and the accessory nipples help to distinguish this condition from Nager AFD. All of the children have normal intelligence and development; most show normal growth. All of the six cases have occurred sporadically.


A new syndrome of refractory sideroblastic anemia with vacuolization of marrow precursors and exocrine pancreatic dysfunction.

In the past decade, we have studied four unrelated children with what we believe is a previously unreported disorder affecting the bone marrow and exocrine pancreas. During infancy these patients had the onset of severe, transfusion-dependent, macrocytic anemia plus a variable degree of neutropenia and thrombocytopenia. Their bone marrows had normal cellularity but were characterized by remarkable vacuolization of erythroid and myeloid precursors, hemosiderosis, and ringed sideroblasts. The vacuoles probably represented manifestations of cellular degeneration and death. In two patients, in vitro bone marrow cultures showed abnormal erythroid and myeloid progenitor cell growth and, in one child, abnormal vacuolated erythroid colonies. Family histories were unrevealing, parents were hematologically normal, and both sexes were involved. There was no evidence of specific nutritional deficiencies or exposure to agents associated with marrow vacuolization. A number of therapeutic interventions produced no effect. One child had clinical malabsorption. This child and one other had extensive pancreatic fibrosis at autopsy. The other two patients had findings indicating exocrine pancreatic dysfunction. Two children had splenic atrophy. This new syndrome, with associated bone marrow and exocrine pancreatic dysfunctions, differs in several respects from the syndrome of pancreatic liposis and neutropenia described by Shwachman et all and Bodian et al, and from other conditions with vacuolization of the marrow or sideroblastosis.


Human chorionic somatomammotropin, estriol and oxytocinase as indexes of fetal growth.

A group of 56 women with high risk pregnancies were studied since the 32nd week of gestation. With the aim of obtaining reliable fetal growth indicators, maternal serum hCS, estriol and oxytocinase levels were determined. hCS and estriol were determined by specific radioimmunoassays and oxytocinase with a colorimetric method. Mean values obtained the week before delivery of both hormones and the enzyme were correlated with the weight of the newborns. The correlation coefficients were 0.30, 0.33 and 0.30 for hCS, estriol and oxytocinase respectively (Figs. 2, 3 and 4). The newborns were classified into two groups, small for date and adequate weight for gestational age. Maternal hCS level corresponding to newborns with adequate birthweight for their gestational age was 7.94 ug/ml. This value was statistically higher than that corresponding to the group of small-for-date newborns, which was 5.15 ug/ml (Fig. 5). Similar results were obtained when the maternal estriol levels were considered according to the birthweight (Fig. 7). The same analysis applied to oxytocinase values did not show statistically significant differences. Arbitrary critical levels were established for hCS and estriol at 7 ug/ml and 35 ng/ml respectively. When values were below these levels, newborns would have greater possibility of being small for dates (Figs. 6 and 8). The predictive value was best when both hormones were considered concomitantly (77%) (Fig. 9). These results indicate the suitability of considering hCS and estriol levels in order to assess fetal growth.


HCS, estriol and oxytocinase in maternal serum and neonatal condition in high risk pregnancies.

In order to find a reliable index of fetal wellbeing, maternal estriol, hCS and oxytocinase levels were related with condition of the neonate. Fifty six high risk pregnancies were studied. Estriol and hCS were determined by specific radioimmunoassay and oxytocinase with a colorimetric method. The condition of the newborn was evaluated by the APGAR score. Neonates were divided into two groups, depressed (APGAR score 0-6) and vigorous (APGAR score 7-10). When the mean birthweights of both groups were statistically different, maternal estriol levels were corrected to avoid the influencing factor of newborn weight. Mean maternal estriol level corresponding to vigorous newborns was 46.73 ng/ml. This value was statistically higher than that corresponding to the group of depressed newborns, which was 26.25 ng/ml (Fig. 1). The mean birthweight of depressed infants (2,382.75 g) was statistically lower than that of the vigorous group (3,044.75 g). The corrected mean maternal estriol values of vigorous neonates (45.44 ng/ml) was different from that of depressed ones (25.14 ng/ml) (Fig. 2). When patients were divided according to maternal diseases (diabetes, vascular pathology, Rh sensitization) serum estriol levels of the mother were statistically different according to the Apgar score of the newborns. There was no significant difference between serum hCS and oxytocinase levels of mothers with depressed and vigorous newborns. Discarding fetal weight as an influencing factor in maternal hormone level, our results indicate the suitability of maternal serum estriol determinations to predict condition of the newborns in high risk pregnancies.


The effect of heparinized blood exchange transfusion on endotoxin induced disseminated intravascular coagulation (DIC).

Sepsis of the newborn induced by gram negative bacteria, especially E. coli is often accompanied by a severe coagulation disorder. It can be treated by blood exchange transfusion (ET) with heparinized blood. In this study the hematological effect obtained by the exchange transfusion was investigated in rabbits after induction of a generalized Shwartzman reaction by two spaced injections of endotoxin (75 microgram/kg) 24 hrs. apart. Three groups of 6 animals each were investigated: group I: without endotoxin but with ET (controls); group II: endotoxin without ET; group III: endotoxin with ET. Fibrinogen, soluble fibrin monomer complexes (SFMC), fibrin(ogen) degradation products (FDP), platelet- and leukocyte counts and urine volume (ml/hr) were estimated. In group II a decline in the fibrinogen level, and in platelet and leukocyte count, as well as an increase in SFMC and FDP could be observed from 6 hrs. on after the second endotoxin injection. In group III 6 hrs. after the second endotoxin injection, exchange transfusion with heparinized blood was performed. Variance analysis showed significant differences in all parameters, except in the urine volumes after exchange transfusion between group III and group II. By exchange transfusion an approach of the values towards the values of the controls could be recognized. The findings indicate, that by blood exchange transfusion the hematological consequences of the endotoxin induced DIC can be corrected, while the dysfunction of the kidneys can be improved only slightly.


The assessment of lung maturity in infants of diabetic mothers, by means of L/S ratio determination in tracheo-pharyngeal aspirate.

The respiratory distress syndrome is more common in the newborns of diabetic mothers. The comparatively high rate of incidence of this syndrome depends neither on gestational age nor delivery route. In view of these facts, the evaluation of fetal lung maturation of diabetic mothers seems to be of the utmost importance. The methods usually employed for the determination of fetal lung maturation are of limited value, because occasionally L/S ratio values, which usually indicate fetal lung maturation, may fall to below critical levels. It is, therefore, extremely important to assess lung maturity in the newborn of a diabetic mother at the time of delivery. In 15 pregnancies complicated by diabetes mellitus of all degrees of severity (A-D), according to the classification of P. WHITE, L/S ratio in amniotic fluid prior to delivery was determined. L/S ratio was determined in tracheopharyngeal aspirate, as well, soon after delivery. In all cases the foam stability test was done in the amniotic fluid before delivery and, when there was a sufficient quantity, also in the tracheo-pharyngeal aspirate. According to the foam test and L/S ratio in the amniotic fluid, all fetuses supposedly had normally matured lungs. Nevertheless, according to these two tests in the tracheopharyngeal aspirate, results indicate lack of full lung maturity in four cases. In fact, all these four newborns developed the respiratory distress syndrome. This test appears to be reliable, simple and non-invasive, and is therefore recommended in babies with diabetes of all degrees of severity, and in all gestational ages.


A new tocograph with cassette recording system and separate servo graphic recorder.

In order to register contractional activity, especially in the case of high-risk pregnancies, a tocograph was develop by means of which the contractions are registered by a small cassette recorder, which the patient can carry by about with her. A separate graphic recorder is responsible for the playback and this recorder remains at the doctor's practice. The patient is able to register her contractions herself as the unit is so simple to use. The recording section weighs only 500 grams, including the specially developed pressure transducer with optical distance-meter. The tocograph is produced in series.


Neonatal meningitis due to Citrobacter koseri.

A five day old neonate was diagnosed as having bacterial meningitis and commenced on Ampicillin and Flucloxacillin. The organism was then found to be Citrobacter koseri and the antibiotics changed to Chloramphenicol systemically for two weeks. The child made an uneventful recovery. At four weeks of age her head circumference had increased unacceptably and a computerised axial tomography scan revealed a large frontal lobe abscess. Aspiration revealed a large pus filled cavity and Citrobacter koseri grown from the pus. The abscess was treated with repeated aspirations, often of 30-40 mls., and installation of Chloramphenicol combined with systemic Chloramphenicol for three weeks. At six months of age her head circumference was within normal limits and the was developmentally normal with no detectable neurological sequelae.


Effects of resource availability and importance of behavior on the experience of crowding.

According to the interference formulation, participants in a crowded setting will experience interference to the extent that behavioral goals conflict with environmental conditions. The importance of the behavioral goals directly affects not only the magnitude of the interference but also the mechanism by which people cope with interference. It was reasoned that important goals would induce a more active coping strategy in a crowded setting than in an uncrowded setting and would maintain task performance at the price of increasing crowding stress. When the behavioral goal is unimportant, decrements in task performance preclude a rise in stress. A laboratory study manipulated group size, in order to vary the availability of resources, and the importance of the task behavior. The predictions were confirmed, and partial confirmation was obtained for predictions involving the effects of the internal-external personality dimension. The meaning of the results is discussed in terms of other findings in the literature on crowding and the mediating role of the type of mechanism used to cope with interference.


The birth order puzzle.

Studies relating intellectual performance to birth order report conflicting results, some finding intellectual scores to increase, others to decrease with birth order. In contrast, the relationship between intellectual performance and family size is stable and consistently replicable. Why do these two highly related variables generate such divergent results? This birth order puzzle is resolved by means of the confluence model that quantifies the influences upon intellectual growth arising within the family context. At the time of a new birth, two opposing influences act upon intellectual growth of the elder sibling: (a) his or her intellectual environment is "diluted" and (b) he or she loses the "last-born's handicap" and begins serving as an intellectual resource to the younger sibling. Since these opposite effects are not equal in magnitude, the differences in intellectual performance among birth ranks are shown to be age dependent. While elder children may surpass their younger siblings in intellectual performance at some ages, they may be overtaken by them at others. Thus when age is taken into consideration, the birth order literature loses its chaotic character and an orderly pattern of results emerges.


Some child-rearing antecedents of criminal behavior in adult men.

Records collected during childhood and coded prior to knowledge of adult behavior provided information about the childhood homes of 201 men. Thirty years later, information about criminal behavior was collected from court records. Multiple regression and discriminant function analyses indicate that six variables describing family atmosphere during childhood--mother's selfconfidence, father's deviance, parental aggressiveness, maternal affection, parental conflict, and supervision--have an important impact on subsequent behavior.


The role of facial response in the experience of emotion.

Facial expression and emotional stimuli were varied orthogonally in a 3 x 4 factorial design in order to test whether facial expression is necessary or sufficient to influence emotional experience. Subjects watched a film eliciting fear, sadness, or no emotion, while holding their facial muscles in the position characteristic of fear or sadness, or in an effortful but nonemotional grimace; those in a fourth group received no facial instructions. The subjects believed that the study concerned subliminal perception and that the facial positions were necessary to prevent physiological recording artifacts. The films had powerful effects on reported emotions, the facial expressions none. Correlations between facial expression and reported emotion were zero. Sad and fearful subjects showed distinctive patterns of physiological arousal. Facial expression also tended to affect physiological responses in a manner consistent with an effort hypothesis.


Self-directed attention, awareness of bodily states, and suggestibility.

Two studies tested the hypothesis that self-directed attention would cause increased awareness of internal states and would thus reduce suggestibility effects. Experiment 1 applied this reasoning to the experience of an emotion. Males viewed moderately arousing slides of female nudes after being led to expect the slides to be either highly arousing or nonarousing. As predicted, ratings of the slides corresponded less with these experimentally-manipulated anticipations when self-focus was heightened by the presence of a mirror than when it was not. Experiment 2 examined a different internal experience: the perception of taste. Some subjects were led to expect a strong flavor as part of a test series, and other subjects were led to expect a weak flavor. Subjects high in private self-consciousness were less affected by this expectancy manipulation and more accurate in reporting their actual internal state than were subjects low in private self-consciousness. Discussion centers on the theoretical implications of the findings.


Effect of 60Co-irradiation on penicillin G procaine in veterinary mastitis products.

The effect of 60Co-irradiation on penicillin G procaine in a peanut oil-based veterinary mastitis product was examined by reversed-phase high-performance liquid chromatography (HPLC). The HPLC method is capable of separating and quantifying procaine, penicillin G, and various degradation compounds. Penicillin G recovery from a placebo formulation was 100.4% with a relative standard deviation of less than 1%. When irradiated at 4.0 Mrads, the penicillin G in two product lots decreased slightly (approximately 1-2%) with a corresponding increase in two compounds inherently present in bulk penicillin G powder. These compounds may be formed in abundance by treating penicillin G in an acidic solution. From the mass spectrometric analysis and the relative retention data with authentic compounds, these compounds were identified as benzylpenilloaldehyde and benzylpenaldic acid. Values obtained by the HPLC method on the product irradiated and stored at various temperatures correlated well with those of the microbiological assay. No significant decrease in the procaine was detected even after 4.0-Mrad irradiation. The HPLC method is applicable for analysis of other beta-lactam antibiotics.


Quantitative structure-selectivity relationships: selective drug design.

The concept of complex selectivity (Scn) permits the investigation of quantitative structure--selectivity relationships in the presence of n side effects; Scn permits differentiation of the most selective molecules rather than the most active ones in a congener series. Selectivity quantification in the presence of n side effects facilitates molecular comparisons. The information provided by Scn and its changes with increasing n is discussed. The proposed mathematical model is applied to the study of the selectivity of some antibiotics and antibacterial agents.


Hydrodynamic characterization of a spin-filter dissolution device.

The spin-filter dissolution device was characterized using a two-dimensional convective diffusion model. Experimental model testing involved analysis of dissolution rates from nondisintegrating salicylic acid disks. The disks were prepared as double-layer tablets, with an ethylcellulose layer as a nondissolving surface. For each dissolution run, the disk was positioned so that the dissolving salicylic acid surface was parallel to the flow of the circulating fluid. Experimental variables included the stirring speed, the tablet radius, and the distance of the tablet from the stirring source. At the farthest distance from the stirring source, the average numerical exponents for stirring speed and tablet radius were 0.58 and 1.54, respectively, which compare favorably with the values of 0.50 and 1.50 from the model. When the dissolving salicylic acid surface was positioned closer to the stirring source, the numberical exponent for the stirring speed increased significantly, while the average numerical exponent for the tablet radius was lowered to 1.07, indicating a change is dissolution mechanism as a function of distance from the stirring source. These data indicate that dissolution rates are not necessarily proportional to surface area as predicted by the Nernst equation and that distance from the stirring source is significant.


Linear pharmacokinetics of orally administered fenoprofen calcium.

The bioavailability of fenoprofen from three different fenoprofen calcium capsule formulations containing the equivalent of 60, 165, and 300 mg of fenoprofen was determined in two studies. In the first study, 12 subjects received one capsule of each formulation according to a three-period crossover design. The second study required each of 13 subjects to receive 300 mg of fenoprofen equivalent of the 60- and 300-mg capsules and 330 mg of the 165-mg capsule. The initial study provided information on the linearity of fenoprofen pharmacokinetics, and the second study established that the three capsule formulations were bioequivalent. The bioavailability parameters Cmax, tmax, and AUC0--12 hr for the drug in plasma were consistent with a linear pharmacokinetic model, as were the amounts of fenoprofen and hydroxyfenoprofen excreted in the urine. These data show linearity of kinetics for fenoprofen in plasma throughout the 60--300-mg dosage range after a single dose. Physical measurements of each capsule formulation drug content, weight variation, and dissolution showed the products to be uniform and readily soluble.


Cholesterol solubility in organic solvents.

The 37 degree cholesterol solubilities in over 50 solvents, including the homologous n-alkanols through dodecanol and homologous ethyl carboxylates through the undecanoate, and the 37 degree beta-sitosterol solubilities in the n-alkanols through decanol are reported. Additionally, solubility data for cholesterol at 7, 17, and 27 degrees in the alcohol series were obtained. These measurements allowed the calculation of heats of solution for cholesterol in the alkanols, which range from 7.5 kcal for methanol to 4.3 kcal for decanol and which tend to decrease, although irregularly, with increasing alkanol chain length. A solubility maximum in all of these series for both solutes was observed between a chain length of six and seven. A surprisingly irregular, odd-even alternating solubility pattern was noted for cholesterol in the alkanols at all four temperatures. Experimental evidence indicated that this pattern was due to solvent-induced crystalline changes, presumably solvate formation, in each alkanol solvent through C10. Overall, the solubility studies screened solvents for their utility in dissolving cholesterol and, thus, cholesterol gallstones. To these ends, some limited dissolution experiments were performed, which indicated that the solution rate is directly related to the measured solubility in organic solvents. The dissolution behavior is thus different from micellar bile salt solutions, in which a significant interfacial barrier controls kinetics.


Bioavailability of chlorothiazide tablets in humans.

A urinary excretion bioavailability study was conducted in 12 healthy male subjects to evaluate three 250-mg and three 500-mg chlorothiazide tablet products. The study was a crossover design, and urine samples were collected 1, 2, 3, 4, 6, 8, 12, and 24 hr after administration of each dose. The resulting data were statistically analyzed for significant differences in cumulative percent of dose excreted at each sampling time, total drug recovery after 24 hr, maximum excretion rate, and time of maximum excretion rate. No statistically significant differences were found between the three 250-mg tablets tested. The urinary drug recovery after administration of one of the 500-mg products was significantly (p less than 0.05) lower than that from the other two 500-mg tablets. The total mean recovery from each product ranged from only 11 to 20%, indicating that in general chlorothiazide was not well absorbed following oral administration. Attempts at correlating the urinary excretion data with the dissolution rate determinations were not successful.


Effect of temperature and an ion-exchange resin on cation diffusion through silicone polymer tubing.

Permeation of cations through silicone rubber tubing was measured, and the effect of an ion-exchange resin on the cation diffusion was determined. Silicone rubber has been used as a biomedical polymer and shows a very low solubility to ionizable species. Correlations between the calculated diffusion coefficients, with and without the resin, depended on the charge and number of waters of hydration for each cation. These increases ranged from 1.11 for potassium to 3.06 for iron, multiplied by the diffusion coefficient as a result of the resin. Solubilities of each cation in the polymer were temperature dependent. Activation energies were calculated for each cation by measuring the increased permeation with increasing temperature, with and without the resin. Decreasing magnitudes of activation energies ranged from 0.91 for sodium to 0.57 for iron when the resin was present. Correlations were established between the measured activation energies and reported free energy change for the hydration of each cation.


Species difference in GI motor response to somatostatin.

Acute experiments were performed on overnight fasted chloralose-urethan anesthetized dogs, cats, rabbits, and rats. Under these conditions, somatostatin practically abolished gastric contractions and decreased GI tonus in all species examined. The canine duodenum, jejunum, and ileum exhibited only a contractile response to somatostatin, whereas motor activities of the small intestines of the cat, rabbit, and rat were inhibited. In all instances and at all dosages, both the inhibitory and excitatory effects showed suggestions of tachyphylaxis. The data also indicate that excitatory or inhibitory effects were not dependent on the presence of long arc pathways. It is concluded that somatostatin exerts a direct stimulatory effect on the canine small intestine that is mediated by the muscularis mucosa.


High-performance liquid chromatographic microdetermination of indoprofen in human milk.

A previously reported high-performance liquid chromatographic (HPLC) method for indoprofen determination in physiological fluids was modified and extended to provide quantitative data on drug concentrations in human milk samples at a low nanogram per milliliter level. The reversed-phase HPLC technique was modified to give a better separation of the drug and milk components. To achieve the necessary cleanup for low level determination, the milk samples required protein precipitation, liquid-liquid drug extraction, and concentration. Excellent indoprofen recovery was obtained with this technique; the average recovery from 20 milk samples spiked with various nanogram drug levels was 95%. The analytical technique showed excellent reproducibility; the calibration solutions over 15 days had a relative standard deviation of 3.2%. Results for indoprofen levels in milk and plasma samples from seven subjects who received either a single or multiple oral drug dose are presented.


Simple analogs of the toxin callicarpone.

Callicarpone, a component 10 times as toxic to fish as rotenone, has been isolated from the leaves of Callicarpa candicans. It is reasonable to assume that callicarpone will act as an insecticidal agent as does rotenone. Therefore, the structure-activity relationship of callicarpone was examined by synthesizing a series of compounds having certain of its structural features. Those compounds were tested for insecticidal and antimicrobial activities. A study of synthetic analogs elucidated the functional group chemistry of callicarpone so that a synthesis might be undertaken. Piperitone oxide showed approximately 1/100th the activity of rotenone against Daphnia magna. 1-(alpha-Hydroxyisopropyl)-3-oxocyclohexene oxide showed activity against myobacterium while 2,3,4,6,7,8-hexahydronaphthalene-1,4-dione showed inhibitory activity against the mycobacterium and two yeasts.


Kinetic parameter estimation by numerical algorithms and multiple linear regression: application to pharmacokinetics.

Two numerical examples are presented to illustrate the application of the proposed method of parameter estimation in pharmacokinetics. Results for a system exemplifying first-order kinetics indicate that parameters estimated by the proposed procedure compare favorably with those estimated by a nonlinear regression method. In a simulated example characterized by Michaelis-Menten elimination kinetics, the accuracy of the estimated parameters was comparable to that expected, verifying the validity of the method. The importance of the numerical approximation algorithms was demonstrated also.


Impurities in drugs III: Trihexyphenidyl.

Two lots of trihexyphenidyl hydrochloride raw material, one lot of elixir, and 10 lots of tablets were examined for impurities by TLC. Impurities found were 1-phenyl-2-propenone, 3-piperidinopropiophenone, and 3-aminopropiophenone. Not all impurities were present in all lots, and none exceeded 1.9% of the label drug claim. Impurities were identified by mass spectrometry and by comparison of TLC Rf values and GLC retention times to those of synthesized specimens of the impurities.


High-pressure liquid chromatographic assay for griseofulvin in plasma.

A high-pressure liquid chromatographic procedure was developed for griseofulvin assay in human plasma. The method utilized warfarin as an internal standard and easily quantitated griseofulvin plasma levels as low as 0.10 micrograms/ml. The method was compared to two fluorometric assay methods and was more specific for griseofulvin. Assay of 6-demethylgriseofulvin isolated from human urine demonstrated that this material was not responsible for the interferences apparent in the fluorometric procedures.


Mercaptoalkylamine coordination compounds of platinum(II) and palladium(II) and their anticancer activity.

A series of coordination compounds of platinum(II) and palladium(II) with several amino- and heterocyclic aminoalkyl mercaptans was synthesized, and their structures were determined by IR absorption and elemental analyses. Because of the tendency of the mercapto group to undergo oxidation on reaction with metals, as observed with copper(II), the complexes were obtained by use of the aminoalkylthiosulfates, which decomposed to the thiol in either acid or alkaline solution. Furthermore, palladium-sulfide complex formation by reaction with an aminoalkyltrithiocarbonate made it possible to distinguish between metal-sulfur and metal-nitrogen bonds in the 650--400-cm-1 region. Anticancer screening against L-1210 lymphoid leukemia in mice did not reveal positive activity among the compounds tested.


Solubility in amide-water cosolvent systems II: Cosolvent excess at solute surface.

The solubility of methylparaben was determined at 25 degrees in a series of amide-water cosolvent systems. The data were used to demonstrate the possibility of an amide excess at or near the ester solute over that in the bulk solvent. The analysis, stemming from an interfacial tension-solute area solubility model proposed by earlier workers, involved data obtained as a function of amide concentration and as a function of amide alkylation. Both sets of data support the basic contention of the paper.


High-performance liquid chromatographic assay of cyclophosphamide in raw material and parenteral dosage forms.

A simple, specific, high-performance liquid chromatographic method is described for the assay of cyclophosphamide as the raw material and in parenteral dosage forms. The assay involves dilution, addition of an internal standard (methyl 4-aminobenzoate), injection onto a reversed-phase C18 column, and quantitation with a UV detector at 200 nm. Sensitivity is approximately 40 micrograms/ml. Decomposition products elute at the void volume and do not interfere.


Controlled release of tetracycline I: In vitro studies with a trilaminate 2-hydroxyethyl methacrylate-methyl methacrylate system.

A membrane-controlled drug delivery device was developed to release tetracycline at zero-order rates. The tetracycline delivery vehicle is a trilaminate disk consisting of core and coating membranes fabricated from a series of 2-hydroxyethyl methacrylate and methyl methacrylate copolymers. Appropriate adjustment of the monomer composition ratio imparts a hydrophobic nature to the copolymer outer coating membrane (relative to the core material), which serves as the rate-limiting membrane in drug diffusion. The trilaminate disks demonstrated a zero-order tetracycline release over 4 months in vitro. The zero-order release rate was a function of the general device geometry, coating membrane thickness, disk surface, area, level of core reservoir drug loading, and membrane coating copolymer composition. Permeability parameters of tetracycline diffusion through a series of 2-hydroxyethyl methacrylate-methyl methacrylate copolymer membranes were determined by a flux-lag time method. Equilibrium hydration values of these membranes also were determined. The ability of trilaminate 2-hydroxyethyl methacrylate-methyl methacrylate devices to release tetracycline at constant rates over a prolonged period offers unique therapeutic and investigational possibilities.


Analysis of nitrosamines in aqueous and biological fluids based on measurement of photochemically liberated nitrite.

A method is described for the analysis of nitrosamines in aqueous solution and in biological fluids (blood, plasma, and rat liver microsomal suspensions). The method is based on photochemical degradation of the nitrosamine in a controlled environment to yield the corresponding amine and nitrite ion, and the latter is subsequently used to form a chromophoric or fluorescent product. The analysis scheme is a modular three-component system consisting of a column to remove contaminating nitrite prior to photolysis, a photochemical reactor, and a chemical reactor. Additional modules are used to accommodate biological samples or large-volume (5--50 ml) aqueous samples. In this study, N-nitrosopyrrolidine, N-nitrosodimethylamine, and N,N-diethanolnitrosamine were utilized as substrates. Because of intersubstrate variability in the photochemical decomposition rate and overall nitrite yield, the structure (i.e., photochemical behavior) of the particular nitrosamine in the sample must be known prior to analysis. With a colorimetric readout, the sensitivity for analysis of N-nitrosopyrrolidine was 800 ng/ml for a 5-ml sample and the measurement precision was +/- 6% in the biological fluids. Fluorometric analysis improved sensitivity to 4 ng/ml with a precision of +/- 10% in biological media.


Isolation of salicylsalicylic acid, acetylsalicylsalicylic acid, and acetylsalicylic anhydride from aspirin tablets by extraction and high-pressure liquid chromatography.

Aspirin and four salicylate impurities of aspirin (salicylic acid, acetylsalicylsalicylic acid, acetylsalicylic anhydride, and salicylsalicylic acid) were resolved by silica gell TLC and by high-pressure liquid chromatography (HPLC) on a reversed-phase C18 column. Care was necessary in the choice of a column because of similar column failed to resolve these five compounds. Salicylsalicylic acid was isolated from aspirin tablets by extraction followed by reversed-phase C18 HPLC. The structure of this compound was confirmed by comparison with an authentic sample of salicylsalicylic acid by HPLC, TLC, IR and UV spectrophotometry, and mass spectrometry. Two other compounds, acetylsalicylic anhydride and acetylsalicylsalicylic acid, which had been previously identified by chromatography as impurities in aspirin, were isolated and further characterized.


Lyophilization of pharmaceutical injections: theoretical physical model.

A physical model for the lyophilization kinetics of parenteral formulations is presented. Mathematical relationships are derived, which involve the simultaneous change in the receding boundary of the ice-vapor interface with time as well as water vapor diffusion across the dry porous matrix and boundary layer. Heat from an external heat source is transferred across the frozen solution to the receding ice surface. The model predicts that the water lost and the receding boundary distance are linearly related to the square root of time when lyophilization is matrix controlled. The mathematical descriptions are predictive of the physicochemical and transport events and can lead to the design of quantitative experiments to relate theory to formulation design.


Flame-ionization GLC assay for fluorouracil in plasma of cancer patients.

A rapid and specific flame-ionization GLC method was developed for the determination of plasma fluorouracil. The chloro analog is used as the internal standard. The method involves the isolation of both the drug and the internal standard from plasma on a strong anion-exchange column at pH 10. Elution is performed with acetic acid in methanol. The evaporated eluate is dissolved in tetrahexylammonium hydroxide. An aliquot of the resulting solution is introduced directly into the gas chromatograph, where conversion to the bishexyl derivatives and subsequent separation take place. The extraction recovery from blank plasma, to which fluorouracil was added, was 96.8 +/- 2.4% (SD). Linearity was proven in the range from 0 to 25 micrograms/ml, whereas the detection limit of the method was estimated at about 2 micrograms/ml of plasma. The within-run precision was determined at three different fluorouracil levels. To demonstrate method applicability, plasma samples obtained from cancer patients to whom 1 g of fluorouracil had been administered intravenously were analyzed.


Influence of cetylpyridinium chloride on corneal permeability to penicillin.

The epithelial surface or the deepithelialized anterior stromal surface of isolated rabbit corneas was perfused for 3 hr with 14C-penicillin in 25 mM Ringer-bicarbonate solution with or without 1% albumin and with or without 0.02% cetylpyridinium chloride. The intact epithelium acted as a barrier to penicillin and impeded the flux rate by 66% when compared to the flux rate across the deepithelialized cornea. The presence of 0.02% cetylpyridinium chloride increased the penicillin flux rate across corneas with an intact epithelial layer to that of deepithelialized corneas. Cetylpyridinium chloride, 0.02%, had no effect on penicillin flux across deepithelialized corneas. The penicillin flux rate across corneas, with or without epithelium, was increased slightly following the inclusion of 1.0% albumin in the bathing solution. The flux rates across deepithelialized corneas in the presence of albumin, with or without cetylpyridinium chloride, were similar to fluxes found in the absence of albumin. Albumin-penicillin "binding" was not a significant factor in impeding penicillin flux, and this binding apparently was not altered by cetylpyridinium chloride. The surfactant appeared to alter epithelial permeability physiologically.


Renal actions of oxyphenbutazone.

Oxyphenbutazone decreased the renal excretion of sodium and water in anesthetized dogs. As these excretions decreased, the drug also produced a decrease in renal blood flow and in the glomerular filtration rate. Blood pressure increased slightly. These changes are consistent with an inhibition of renal prostaglandin synthesis and could explain why oxyphenbutazone is reported to produce weight gain and edema when used clinically.


Effects of pyridoxine hydrochloride (vitamin B6) on chlorpromazine-induced serum prolactin rise in male rats.

To investigate if vitamin B6 inhibits prolactin release and to compare this effect to that of bromocriptine, a known suppressor of prolactin release, a study was conducted in male rats. Animals were pretreated with pyridoxine hydrochloride, pyridoxal hydrochloride, saline, or bromocriptine 30 min prior to receiving varying doses of chlorpromazine hydrochloride. Blood samples were obtained 90 min later and analyzed for serum prolactin by a double-antibody radioimmunoassay. Another study involved pyridoxal hydrochloride and saline pretreatments 30 min prior to doses of chlorpromazine hydrochloride. Blood samples collected 60 min later were also analyzed for serum prolactin. Pyridoxine hydrochloride significantly suppressed the chlorpromazine-induced prolactin rise (p less than 0.01). However, the suppression was significantly less than that produced by bromocriptine (p less than 0.01). Pyridoxal hydrochloride, another natural form of vitamin B6, failed to suppress prolactin under the conditions of both studies. This investigation may lend support to the concept that pyridoxine hydrochloride partially inhibits prolactin by a mechanism not involving dopamine.


Resolution of (+/-)-propranolol.

Two improvements in propranolol resolution were developed. Both the (+)- and (-)-di-(p-toluoyl)tartaric acids were used as the resolving agents. This procedure reduced the number of crystallizations needed to obtain a pure product. Furthermore, synthesis of the resolving agent was improved.


High-performance liquid chromatography of benzodiazepines I: Stability-indicating assay of diazepam tablets.

A high-performance liquid chromatographic procedure was developed for diazepam tablet analysis. This procedure separates the manufacturing intermediate, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one, and the decomposition products, 3-amino-6-chloro-1-methyl-4-phenylcarbostyril and 2-methylamino-5-chlorobenzophenone, from diazepam. The liquid chromatographic procedure is superior to the USP UV assay because it is stability indicating. The method is simple, accurate, and fast, involving only one extraction step. A reversed-phase column and a methanol-water mobile phase were used. Under these conditions, 0.1% of the decomposition products was detectable. Typical samples of diazepam tablets showed no degradation.


Quantitative flash-methylation analysis of phenobarbital.

In phenobarbital measurement by GLC with the flash-methylation technique, using trimethylanilinium hydroxide as a methylating reagent, a small amount of water decomposed phenobarbital and interfered with the quantitative analysis. Thus, both the sample and the methylating reagent must be sufficiently dehydrated to attain quantitative analyses. The hydrolysis decomposition product of phenobarbital was N-methyl-2-phenylbutyramide, as shown by its mass spectrum. The sum of methylated phenobarbital and N-methyl-2-phenylbutyramide (if observed in the spectrum) can be used for an accurate phenobarbital assay in the present flash-methylation technique.


Pharmacokinetics and bioavailability of pyridinol carbamate in humans.

The pharmacokinetics of two pyridinol carbamate formulations were studied after a single oral administration in 10 healthy volunteers. An open one-compartment model described the evolution of plasma concentrations as a function of time. Pyridinol carbamate was rapidly absorbed (mean lag time from 0.36 to 0.38 hr). Its elimination half-life ranged from 3.3 to 7.9 hr. The two formulations were bioequivalent.


Correlations of parotid saliva and plasma lidocaine concentrations in rats.

The concentration ratios of parotid saliva to plasma lidocaine were determined in rats after a single dose (10 mg of lidocaine/kg) and constant infusion (60 micrograms of lidocaine/kg/min). Parotid saliva and plasma samples were obtained at 10, 20, and 30 min after single-dose lidocaine administration and at 70, 80, and 90 min after the initiation of a lidocaine infusion. The saliva/plasma concentration ratios for lidocaine after single-dose administration decreased from 1.13 +/- 0.03 at 10 min to 0.51 +/- 0.06 at 30 min, whereas the ratios determined during the lidocaine infusion remained constant (0.43 +/- 0.03, 0.45 +/- 0.03, and 0.43 +/- 0.04) over the time period tested. The variable saliva/plasma concentration ratios obtained after single-dose administration may be associated with rapid drug distribution between the plasma and peripheral compartments and variation in lidocaine binding to plasma proteins. However, during constant lidocaine infusion, a steady-state concentration was achieved within 70 min, as demonstrated by the constant saliva/plasma concentration ratios.


Separation and spectral properties of diisopropylphosphate, the major decomposition product of isoflurophate.

The reaction of water with isoflurophate to form diisopropylphosphate was examined and confirmed. Isolation of this decomposition product from an antiglaucoma drug formulation is described. A known reference compound was isolated from a commercial mixture also containing the monoisopropyl ester. The isolation, purification, and molecular spectroscopic and elemental confirmation of structure are described. IR, NMR, and mass spectra are included. Additionally, a GLC procedure and parameters used to identify diisopropylphosphate in a degraded peanut oil formulation of isofluorphate are reported. Reaction mixtures of this drug with water and sodium hydroxide were analyzed by GLC with the expected results.


Imipramine affects autonomic control of sinoatrial rate in isolated right atrial preparations.

The effects of imipramine on sinoatrial rate and chronotropic responses to transmural stimulation (TS) were studied in the isolated guinea-pig right atrial preparation. The negative chronotropic response (cholinergically mediated rate decrease) to TS was progressively inhibited by imipramine (5 x 10(-6) M). This inhibition can be attributed directly to an "atropine-like" effect of this drug. The positive chronotropic response (adrenergically mediated rate increase) to TS was markedly potentiated by imipramine at similar therapeutic doses; higher doses (5 x 10(-5) M) substantially depressed this rate response. This depression of the adrenergic response to TS does not appear to be the result of a blockade of beta adrenergic receptors since imipramine still potentiated the rate increase in response to exogenous norepinephrine at doses where no TS response remained. Basal spontaneous rate was also depressed by imipramine at high doses (5 x 10(-5) M), both in the absence and presence of autonomic blockers.


Reduction of gamma-aminobutyric acid (GABA)-mediated transmission by a convulsant benzodiazepine.

In contrast to other benzodiazepine, Ro 5-3663 produces convulsions in mice. The CD50 of 7.0 mg/kg i.v. falls between that of picrotoxin and pentylenetetrazol. An electrophysiological study was made of the effects of this convulsant benzodiazepine on spinal reflexes and on ganglionic depolarization evoked by gamma-aminobutyric acid (GABA). In the unanesthetized spinal cat, Ro 5-3663 (15 mg/kg i.v.)depressed the dorsal root potentials and abolished the dorsal root reflexes evoked by muscle and cutaneous afferent inputs. The monosynaptic reflex was typically depressed, whereas polysynaptic potentials were enhanced. Diazepam reversed the depression of the dorsal root reflex and dorsal root potential produced by the convulsant benzodiazepine and reduced the enhancement of the polysynaptic potential. Presynaptic inhibition was attenuated by the convulsant, whereas strychnine-sensitive postsynaptic inhibition was slightly potentiated. Ro 5-3663 reduced the amplitude and duration of the GABA-evoked negative surface potential recorded from the superior cervical ganglion. The results indicate that the convulsant benzodiazepine acts in an opposite manner to the depressant benzodiazepines and support the hypothesis that these two types of compounds act through a modulation of GABAergic mechanisms.


Changes in primary afferent depolarization after administration of gamma-acetylenic gamma aminobutyric acid (GAG), a gamma-aminobutyric acid (GABA) transaminase inhibitor.

gamma-Acetylenic gamma-aminobutyric acid (GAG), an irreversible inhibitor of GABA transaminase, increased the concentration of GABA in feline spinal cords to 239% of the control value by 225 min after its injection. After administration of GAG to spinally transected cats, the height of the segmentally evoked dorsal root potential (DRP), which is generated at one point via a GABA synapse, was increased to more than twice the control value although the area increased only slightly. However, GAG had no effect on the segmental DRP in the decerebrate cat. In contrast, the DRP evoked in decerebrate cats by electrical stimulation of the brain stem, which is probably mediated by GABA, was decreased by administration of GAG. These effects of GAG were accompanied by the development of spontaneous primary afferent depolarizations which resembled spontaneous DRPs in both spinal and decerebrate cats. The temporal and size correlation between spontaneous DRPs occurring in different spinal roots indicate they are generated by an interneuronal pathway that is released by the action of GAG. The action of GAG on the segmental DRP in the spinal but not decerebrate preparation is also most easily explained by GAG-induced effects on interneuronal pathways. These data suggest GABA transaminase inhibition does not affect the axoaxonic GABA synapse mediating the DRP.


Relationship between pharmacokinetics and pharmacodynamics of the beta adrenergic blocking drug sotalol in dogs.

The relationship between pharmacokinetics and pharmacodynamics was studied in dogs using sotalol as a model. The t 1/2 of this drug (4.30 +/- 0.40 hr) in dogs was longer than that of other beta adrenergic blockers. The renal clearance of the drug (4.21 +/- 0.31 ml/min/kg) was approximately 90% of total plasma clearance together with an extensive fraction excreted unchanged (72 +/- 12% of dose) in urine. Significant beta blockade, assessed by the response to isoproterenol tachycardia, was observed without change in blood pressure during the experiments. The log plasma sotalol concentration correlated significantly with the beta blockade (P less than .001). In an attempt to obtain insight into drug concentration-effect-time data, we applied a theory for correlating the observed kinetic data with the pharmacological effects using the elimination rate constant (beta) and the slope of log concentration-effect relationship (m). The rate of decline of drug effects (Rd) derived from this application agreed well with that actually observed in the effect-time interrelations.


Uptake of ouabain by isolated hepatocytes from livers of developing rats.

The kinetics of uptake of [3H]ouabain were studied in hepatocytes isolated from livers of rats of various ages. Accumulation of ouabain in hepatocytes was measured at 1-min intervals for 4 min of incubation. Uptake of the drug was found to increase with the age of the animal. Although Vmax increased with age, there was no discernible difference in Km values. The uptake of [3H]ouabain into hepatocytes isolated from livers of 12-day-old rats could be stimulated by pretreatment of the animal with pregnenolone-16 alpha-carbonitrile. Uptake of [3H]taurocholate into isolated rat hepatocytes did not show a continuous age related pattern similar to that for ouabain. The age dependence of ouabain uptake into isolated rat hepatocytes demonstrated in this study is evidence that a low hepatic uptake capacity is the mechanism by which ouabain exhibits greater toxicity in the newborn rat.


Effect of morphine on calcium uptake by lysed synaptosomes.

The effect of morphine on the uptake of 45Ca++ was studied in lysed synaptosomes obtained from homogenates of whole mouse brain. The addition of morphine, 10(-6) M, to the incubation medium or acute administration of 10 or 20 mg/kg s.c. resulted in a decrease in 45Ca++ uptake; this decrease was observed only in the presence of ATP (3 mM). In contrast, after morphine pellet implantation (72 hr) to induce tolerance and physical dependence, an enhancement of lysed synaptosomal 45Ca++ uptake occurred; the increase was obtained in the presence but not in the absence of ATP. The enhancement of Ca++ uptake appears to be related with the degree of tolerance and dependence development since a linear relationship was noted between the time of morphine pellet implantation and the increase in 45Ca++ uptake by lysed synaptosomes. The acute inhibitory action on 45Ca++ uptake by morphine was prevented in vitro by naloxone, 1.9 x 10(-8) M, and in vivo by 2 mg/kg of naloxone s.c. and the chronic enhancing action of morphine by the simultaneous implantation of a naloxone pellet with the morphine pellet. The present findings lend further support to our previous reports in which we suggest that alterations in Ca++ flux may be involved with morphine analgesia, tolerance and physical dependence.


Chronic amphetamine administration to cats: behavioral and neurochemical evidence for decreased central serotonergic function.

Chronic administration of amphetamine to cats (twice daily, in doses increasing from 5 to 15 mg/kg over a 10-day period) elicited a number of behaviors, e.g., limb flick and abortive groom, characteristic of the action of hallucinogenic drugs and dependent on a depression of central serotonergic neurotransmission. This drug treatment produced large decreases (-40 to -60%) in central nervous system serotonin (5-HT) and its major metabolite, 5-hydroxyindoleacetic acid (5-HIAA), when measured either 6 or 24 hr after the last amphetamine injection. The rate of limb flicking returned to a predrug level approximately 5 days after drug withdrawal, at which time 5-HT and 5-HIAA levels had returned to within 30 to 40% of base line. Both 5-HT and 5-HIAA returned to base-line levels within 14 days after drug withdrawal. Norepinephrine (NE), dopamine (DA) and DA metabolites were decreased 60 to 95% by chronic amphetamine treatment and showed little recovery within the 14 days after drug withdrawal. A second experiment examined the latency to onset of the behavioral and neurochemical changes with a constant dose of amphetamine (7.5 mg/kg, twice daily). Limb flicking was significantly increased above base-line levels following 3 days of amphetamine administration, at which time 5-HT and 5-HIAA levels were decreased 30 to 40%. NE, DA and DA metabolites were decreased approximately 50 to 90% by this treatment regimen. A third experiment examined the effects of a low dose of amphetamine (3.75 mg/kg), injected more frequently (every 6 hr for 6 days), to approximate the administration pattern in human amphetamine abuse. This treatment produced significant increases in limb flicking and abortive grooming on days 5 and 6 and resulted in 30 to 40% depletions of 5-HT and 5-HIAA. NE, DA and DA metabolites were decreased by approximately 50 to 90%. These data are discussed in relation to a role for serotonin in amphetamine psychosis and schizophrenia.


Protection against alloxan-induced diabetes by various urea derivatives: relationship between protective effects and reactivity with the hydroxyl radical.

Several urea derivatives (monomethylurea, monoethylurea and diethylurea) give i.p. to mice 30 min before alloxan (75 mg/kg i.v.) were able to prevent the diabetogenic actions of alloxan. Protection by these agents correlated reasonably well with their capacity to react with (scavenge) the hydroxyl radical. Protection did not correlate with the capacity of the above agents to cause a transient hyperglycemia at the point of alloxan administration, which might have also been a potential means of protection. These data extend previously published data on the capacity of hydroxyl radical scavengers to protect against alloxan and add evidence to the concept that the hydroxyl radical, generated within the beta cells, is the species derived from alloxan responsible for the damage to beta cells.


Electrophysiology and pharmacology of striated muscle fibres cultured from dissociated neonatal rat pineal glands.

1. Striated muscle fibres were found in each of twenty consecutive pineal glands cultured from individual neonatal rats.2. In subsequent experiments performed with dissociated cultures of pineal organs pooled from several litters, myotubes were first visible after about 1 week in culture.3. During the next several weeks the myotubes increased in size, developed crossstriations, and began to twitch spontaneously.4. The resting membrane potential increased with age in culture. All myotubes studied showed delayed rectification. Action potentials either occurred spontaneously or could be evoked if the membrane were sufficiently polarized. No spontaneous end plate potentials were seen.5. Acetylcholine (ACh) produced a brief, monophasic depolarizing response. Noradrenaline, serotonin, melatonin, dopamine, and gamma-aminobutyric acid (GABA) had no effect on the resting membrane potential when applied iontophoretically.6. The ACh response was reversibly blocked by 10(-6)M-tubocurarine and irreversibly blocked by 10(-6)M-alpha-bungarotoxin. Atropine (10(-4)M) reduced the amplitude and shortened the time course of the ACh response, and 10(-3)M-atropine produced complete but reversible inhibition.7. We conclude that pineal muscle fibres are electrophysiologically and pharmacologically similar to skeletal muscle fibres in vitro. Although the pineal gland has undetectable levels of ACh, pineal muscle develops ACh receptors but not noradrenaline, serotonin, melatonin, dopamine, or GABA receptors mediating electrophysiological responses, although these latter substances (except dopamine) are found in the pineal.


Studies of the electrical excitability of aorta smooth muscle of rabbit.

1. Electrical records were made from the smooth muscle of rabbit aorta in normal solution and after excitation by noradrenaline, by the partitioned chamber method.2. Noradrenaline (3 x 10(-7) g/ml.) produced depolarization and periodic slow potentials, the amplitudes of which were decreased by depolarizing currents and increased by small hyperpolarizing currents. Application of strong hyperpolarizing current stopped production of the slow potentials.3. After application of small amounts of noradrenaline, electrical stimulation produced slow potentials.4. Membrane resistance at the top of the slow potential induced by noradrenaline (3 x 10(-7) g/ml.) was decreased to a few percent of the stable potential level during application of noradrenaline.5. The voltage-current relationship of smooth muscle cells in the aorta showed marked cathodal rectification both in standard solution and upon the application of noradrenaline.6. High K (24 mM) elicited periodic slow potentials, the electrical properties of which were very similar to those induced by noradrenaline. Phentolamine (5 x 10(-5) g/ml.) and guanithidine (10(-5) g/ml.), however, blocked the production of these slow potentials.7. The conditions required for the production of slow potentials are discussed.8. Evoked slow potentials by current flow during application of noradrenaline (3 x 10(-7) g/ml.) was recorded at 5 mm from the stimulating partition. Thus it is concluded that the slow potential can be conducted.


Effects of acetylcholine on the smooth muscle cell of isolated main coronary artery of the guinea-pig.

The effects of ACh on the smooth muscle cell membrane and mechanical property of the guinea-pig main coronary artery were observed by micro-electrode and isometric tension recording methods. 1. The membrane potential was low (--44 mV) and the membrane was electrically quiescent. Application of outward current pulse generated only a small graded response. The current--voltage relationship was linear for application of inward current pulses. 2. In low external Na or Cl solution the membrane was hyperpolarized. In external K solution of the 1.2--17.8 mM the membrane potential remained nearly the same; however increasing it to more than 29.5 mM depolarized the membrane. The maximum slope of depolarization was 42 mV per tenfold increase in external K. These results indicate that both Na and Cl equilibrium potentials were positive to the resting membrane potential. 3. ACh (greater than 10(-8) g/ml.) hyperpolarized the membrane, to a maximum of --67 mV with 10(-6) g ACh/ml. The dose--response relationship was sigmoidal, and the hyperpolarization was suppressed by atropine (10(-7) g/ml.). In external K of 1.2--29.5 mM, the application of 10(-6) g/ml. ACh hyperpolarized the membrane; this ACh-induced hyperpolarization was maximal in 1.2 mM-K (from --42.4 to --82.4 mV). When the hyperpolarization produced by 10(-6) g ACh/ml. was plotted against the external K concentration on a log scale, the relationship was linear above 1.2 mM-K and similar to that observed between the membrane potential and external K concentration between 29.5 and 118 mM in the absence of ACh. However, in a solution containing less than 1.2 mM-K, the amplitudes of ACh-induced hyperpolarization were reduced. 4. In Na- or Cl-deficient solution the membrane was hyperpolarized. The peak hyperpolarization to ACh was not modified by these changes in the ionic environments. It is concluded that ACh increases K permeability selectively in this muscle membrane. 5. To observe the reversal potential level of ACh-induced hyperpolarization, the effects of ACh were observed during the hyperpolarization and subsequent recovery of the membrane on rewarming the tissue following cold storage. When the membrane potential was high (less than --70 mV) ACh produced depolarization, but when it was low (greater than --70 mV) ACh produced hyperpolarization. The reversal potential level for ACh-induced potential change was about --70 mV. 6. Application of ACh (greater than 10(-8) g/ml.) evoked a mechanical response. The hyperpolarization of the membrane produced by ACh appeared coincidently with tension development. ACh also enhanced the amplitude of contracture produced by excess external K concentration. 7. It is concluded that ACh might increase K and Ca permeabilities of the membrane and release Ca from the intracellular store, thus causing hyperpolarization of the membrane and contraction.


Mono-and multi-synaptic origin of the early surface-negative wave recorded from guinea-pig olfactory cortex in vitro.

1. Silices of guinea-pig olfactory cortex were cut at 550 micrometer nominal thickness and preincubated at 24 +/- 0.5 degrees C for than 2 1/2 hr. They were then stimulated via the lateral olfactory tract, and field potential recordings were made from all regions of the slice. 2. Potentials recorded resembled those described previously, but it was noticed the early N-wave had two distinct components, which we designated the N'a' wave (earlier) and N'b' wave (later). Evidence was obtained that this was not a consequence of the division of a single population e.p.s.p. (N-wave) into two by a P notch (synchronous discharge of post-synaptic action potentials). 3. In some slices the N'a' wave and N'b' wave had similar thresholds, and in others the N'a' wave had the slightly lower threshold. 4. The N'b' wave was best developed at low frequencies of stimulation (less than 0.1 Hz), and considerably depressed with stimulation above 1 Hz. This was most evident with submaximal stimulation. 5. Exploration of the distribution of peak amplitudes and latencies of the N'a' and N'b' waves showed that the N'a' wave could have been directly initiated by lateral olfactory tract action potentials, while the N'B' wave could not. The N'b' wave amplitude was relatively larger towards the periphery of the slices, away from the tract. In a few cases, an N'b' wave could be recorded in the absence of an N'a' wave at that site. 6. Depth studies showed that the origin of the N'b' wave lay deeper in the slice than that of the N'a' wave. 7. The effect of conditioning stimulation on the N'a' and N'b' waves was examined. The N'b' wave was more depressed at short conditioning intervals than the N'a' wave, and showed less later potentiation. The recovery of the N'b' wave from conditioning was much slowed with submaximal stimulation, and when trials were repeated at low frequency. 8. The N'a' and N'b' components persisted when the slice was warmed to near-physiological temperatures, and showed a similar pattern of response to conditioning stimulation as had been found at lower temperatures. 9. N'a' and N'b' waves could still be recorded when slices were incubated in a medium containing 1.2 mM-Mg2+ and 1.2 mM-Ca2+. These physiological concentrations were about half those routinely employed. There was little or no depression of the N'b' component by conditioning stimulation in this medium. 10. The N'a' wave is probably a result of e.p.s.p.s in apical dendrites of superficial pyramidal cells, initiated by transmitter release from lateral olfactory tract axon collaterals. The N'b' wave may reflect e.p.s.p.s in the apical dendrites of deeper pyramidal cell elicited by firing in recurrent collaterals from superficial pyramidal cell axons.


Changes in motoneurone electrical properties following axotomy.

1. Passive electrical properties, afterpotential properties and the pattern of repetitive discharge induced by constant current injection were studied in axotomized lumbar motoneurones. 2. Following axotomy, the motoneurones showed a larger input resistance and membrane time constant, but had a normal electrotonic length. 3. Duration and peak amplitude of the afterhyperpolarization (ahp) were on average unchanged following axotomy. There was, however, a significant reduction in the conductance underlying the ahp. The distribution of values for ahp duration was also narrower following axotomy, with an absence of long and short values. 4. As in normal motoneurones, the ahp conductance, calculated from the voltage, decayed in an approximately exponential manner with a phase of slower decay corresponding to the hyperpolarizing phase of the ahp. The phase of slower decay was, however, less accentuated and several axotomized motoneurones showed an exponential decay of the ahp conductance. 5. The frequency--current (f--I) curves for the first interspike intervals were, as in normal motoneurones, non-linear, deviating upwards at higher frequencies. The steady-state f--I relations were, however, linear in most of the axotomized neurones. The slopes of the f--I curves were steeper following axotomy. These steeper slopes were well correlated with the decreased ahp conductance. 6. The interspike voltage trajectories were similar to those in normal motoneurones, i.e. concave at low current strength and changing to a convex shape with increasing current injection. The changes in the trajectory shape were not correlated with the changes in the slope of the f--I curves. 7. It is concluded that the afterhyperpolarization conductance is the major factor in the regulation of repetitive firing in axotomized motoneurones.


Effects of dopaminergic antagonist and agonist on thermoregulation in rabbits.

1. The effects of dopaminergic antagonist haloperidol and agonist apomorphine on the thermoregulatory responses of unanaesthetized rabbits to different ambient temperatures (Ta) of 2, 22 and 32 degrees C were assessed. 2. I.V. administration of haloperidol produced dose-dependent hypothermia at 2 and 22 degrees C Ta. At 2 degrees C Ta the hypothermia was due to a decrease in metabolic heat production. At 22 degrees C Ta the hypothermia was brought about by a decrease in metabolism and an increase in ear blood flow. However at 32 degrees C Ta, there was an increase in rectal temperature in response to haloperidol application; this hyperthermia was due to a decrease in both the ear blood flow and respiratory evaporative heat loss (Eres). 3. I.V. administration of apomorphine produced dose-dependent hyperthermia at all the ambient temperatures studied. At 2 degrees C Ta the hyperthermia was due to an increase in metabolism. At both 22 and 32 degrees C, the hyperthermia was brought about by an increase in metabolic heat production and a decrease in ear blood flow. Also, there was an increase in Eres in response to apomorphine at 22 degrees C Ta. 4. The data, in general, indicate that dopamine agonist activates all effector pathways which modulate the autonomic processes of thermoregulation (i.e. respiratory heat loss, peripheral vasomotor tone and metabolism), and that the dopamine antagonist inhibits the activity in all three effector pathways. Such a clear pattern of results is readily expressible in terms of the 'Bligh' model dealing with the aminergic mechanisms of temperature regulation.


Thickness and volume constants and ultrastructural organization of basement membrane (lens capsule).

1. The basement membrane of the crystalline lens of the rat has been found to have the following elastic constants: a Young's Modulus of elasticity of 0.56 +/- 0.38 x 10(6) Nm-2 at low stress and 11.3 +/- 1.9 x 10(6) Nm-2 at rupture, an ultimate stress of 28.8 +/- 4.5 x 10(5) Nm-2, and a maximum percentage elongation of 41.3 +/- 5.8. 2. The ratio of initial thickness of the membrane to the thickness at the point of rupture is 0.271 +/- 0.02 while the similar ratio for volume is 0.461 +/- 0.031. 3. Electron microscopic observations of ultrasonicated fragments of the entire membrane show long filaments in parallel arrays and sheets. The filaments show a periodicity of 3.7 nm and a spacing of 3.5 nm. 4. Electron microscopic observations of collagenase-treated membrane show a poorly staining matrix associated with separate short straight non-periodic filaments some 2.5 nm in diameter. In addition strands project from the ends of the filaments with a diameter of between 0.5 and 1.0 nm. 5. A model is proposed which consists of these filaments, composed of between three and five parallel strands, some 0.8 nm in diameter, wound in a superhelix. 6. The model predicts satisfactorily thickness and volume changes in the membrane when subjected to stress, and also indicates that the filaments would have a similar Young's Modulus of elasticity and ultimate stress to those of collagen. 7. If the basement membrane of the smallest retinal capillaries is subjected to a change of pressure of only 5 mmHg within the vessel lumen, then the membrane is likely to undergo some 30% reduction in thickness.


The effects of hypercapnia, hypoxia, exercise and anxiety on the pattern of breathing in man.

1. The pattern of breathing, defined as the relations between tidal volume and inspiratory and expiratory times, was measured during the stimulation of breathing by carbon dioxide (hyperoxic rebreathing at rest) in twenty-seven healthy, young volunteers. 2. Most of the patterns (twenty) were divisible into two parts, for low (range 1) and high (range 2) tidal volumes. The relations were curved, inverse proportionalities for both inspiration and expiration in range 2, and for expiration in range 1. The relations for inspiration in range 1 were evenly divided between those with constant inspiratory times (type 1) and those with curved, inverse proportionalities (type 2). 3. In four volunteers, direct proportionalities predominated and the patterns were scattered (type 3). 4. Eight of the volunteers (four type 1, two type 2 and two type 3 patterns) repeated the measurements and one changed from a type 1 to a type 2 pattern. 5. Nine of the volunteers also rebreathed during resting hypoxia. Two altered their patterns, and the others had patterns which were superimposed upon those measured during hyperoxic rebreathing at rest. 6. Eighteen of the volunteers also rebreathed (hyperoxic) during light exercise (25 W). Five entrained their breathing frequency to the exercise rhythm and showed exercise patterns with constant inspiratory and expiratory times. The others had patterns which were extensions of those measured during hyperoxic rebreathing at rest. 7. The pattern of breathing in range 1 was measured by steady-state methods in a further ten volunteers at rest with their eyes closed and open, and during mental arithmetic. The pooled average pattern showed that the stress of mental arithmetic shortened both inspiratory and expiratory times, and changed a type 2 pattern into a type 1 pattern.


Spatial and temporal properties of X and Y cells in the cat lateral geniculate nucleus.

1. Extracellular recordings were obtained from units in the dorsal lateral geniculate nucleus of anaesthetized cats. 2. Of sixty-nine units, sixty-three could be unambiguously identified as either X (n = 33) or Y (n = 30) by testing the presence of a null response to stationary sine wave gratings presented in different spatial phases. 3. In response to stationary gratings flashed on and off, Y cells exhibited bigger, more transient responses than X cells. 4. All Y cells but few X cells exhibited a shift effect (modulated periphery effect). 5. In response to drifting sine wave gratings of different spatial frequencies, X cells preferred higher spatial frequencies and showed smaller peak contrast sensitivities and somewhat narrower tuning curves than Y cells. 6. In response to a sine wave grafting of optimal spatial frequency drifting at different velocities, X and Y cells had similar temporal tuning curves. However, Y cells, largely because they preferred lower spatial frequencies, preferred higher drift velocities than X cells. 7. Our data suggest that X and Y cells can be differentiated objectively on the basis of a number of discharge parameters. These parameters are compared with similar data collected by others from neurones in the visual cortex.


Glycine, GABA and synaptic inhibition of reticulospinal neurones of lamprey.

1. Intracellular recordings were made from the cell bodies and axons of giant reticulospinal neurones (Müller cells) of the lamprey and the effects of a variety of putative neurotransmitters tested. Bath-applied acetylcholine, carbamylcholine, norepinephrine, dopamine, histamine and serotonin were without effect. Glycine and gamma-aminobutyric acid (GABA) hyperpolarized and reduced the input resistance of cell bodies but had no effect on the membrane conductance of axons. 2. The threshold dose of bath-applied GABA or glycine for a conductance change in somata was about 0.5 mM and the maximum effect was reached at about 10 mM. The maximum conductance change produced by glycine was always greater than that produced by GABA. 3. Replacement of the sodium in the bathing saline with lithium or choline prolonged the conductance change produced by ionophoretically applied glycine or GABA, suggesting the presence of sodium-dependent uptake systems for glycine and GABA. 4. The reversal potentials for responses to ionophoretically applied glycine and GABA average about --83 mV, the same as that for the inhibitory post-synaptic potential (i.p.s.p.) produced in Müller cells by stimulation of the ipsilateral vestibular nerve. 5. The i.p.s.p. and drug responses appeared to involve an increase in chloride conductance, since their reversal potentials were shifted appropriately by changes in either internal or external chloride. 6. Changes in extracellular potassium concentration also changed i.p.s.p. and drug reversal potentials. However, these effects could be attributed to secondary changes in internal chloride. 7. The receptors for GABA and glycine appeared to be different because of the absence of cross-desensitization and because, at doses below 20 microM, picrotoxin and bicuculline selectively blocked GABA responses while strychnine selectively blocked glycine responses. 8. At concentrations of 20 microM, strychnine eliminated the i.p.s.p. while picrotoxin and bicuculline had no effect. Further, the i.p.s.p. and glycine response of Müller cells located in the isthmic region of the midbrain had the same threshold sensitivity to strychnine. However, the glycine response of other Müller cells was more sensitive to strychnine than was the i.p.s.p. 9. We conclude that glycine is a better candidate for the inhibitory transmitter onto Müller cells than is GABA.


Glutamate and synaptic excitation of reticulospinal neurones of lamprey.

1. Intracellular recordings were made from the cell bodies and axons of giant reticulospinal neurones (Müller cells) of the lamprey, and responses to bath- and ionophoretically applied glutamate and aspartate were studied. 2. Bath-applied glutamate and aspartate depolarized both cell bodies and axons, but there appeared to be an associated conductance increase only in the cell bodies. The depolarization of Müller axons by the bath-applied drugs probably resulted from the passive flow of current into them from spinal cells to which the axons are coupled electrically. 3. The reversal potentials for responses to ionophoretically applied glutamate and for excitatory post-synaptic potentials (e.p.s.p.s) evoked by stimulation of the contralateral vestibular nerve were directly determined in Müller cell bodies which had been damaged by penetration with low-resistance electrodes. The glutamate and e.p.s.p. reversal potentials were identical, the average difference in eight cells being 0.31 mV. The absolute value of the e.p.s.p.--glutamate reversal potential varied from --16 to --35 mV in different cells, with the more negative values occurring in less damaged cells with higher resting potentials. 4. Injection of Cl into Müller cell bodies had no effect on the e.p.s.p.--glutamate reversal potential. Reduction of the extracellular Na concentration to 1 over 10 normal produced a negative shift in the glutamate reversal potential. 5. It is proposed that the natural excitatory transmitter and glutamate produce identical conductance changes in Müller cells, involving an increase in Na and K conductance.


Influence of the vagus nerve on release and action of secretin in dog.

1. The role of cholinergic nerve on plasma concentration of immunoreactive secretin and pancreatic bicarbonate secretion was investigated in conscious and anaesthetized dogs. 2. In conscious dogs with gastric and pancreatic fistulae, I.V. administration of 2-deoxy-D-glucose (2-DG) potentiated the pancreatic bicarbonate secretion stimulated by duodenal acidification. 3. In conscious dogs with same preparation, I.V. administration of atropine inhibited the pancreatic bicarbonate secretions stimulated by duodenal acidification or exogenous secretin. 4. Neither 2-DG nor atropine had any effect on endogenous release of secretin. 5. In anaesthetized dogs, pancreatic bicarbonate secretion stimulated by duodenal acidification was decreased by bilateral cervical vagotomy. However, plasma secretion concentration achieved by duodenal acidification was not different from that of pre-vagotomy state. 6. The data indicate that the changes of cholinergic tone do not affect release of endogenous secretin but alter the exocrine pancreatic bicarbonate secretion stimulated by secretin.


Cold acclimation in the secretory responses of the isolated exocrine pancreas of the rat.

1. The secretory function of the isolated and perfused exocrine pancreas has been studied in the course of cold acclimation in rats that were fed at an ambient temperature of 1 degrees C in an artificial climatic room.2. A series of experiments was carried out in early autumn (autumn series). The sums of the outputs of protein, amylase, zymogen protease, lipase, and juice flow in samples collected for a total of 30 min during and after 5 min stimulation with different concentrations of cholecystokinin-pancreozymin (CCK-PZ; 5-50 m-u./ml.) were simultaneously measured in the autumn series of experiments, and they were plotted against the logarithmic scale of concentration of CCK-PZ to obtain a dose-response relation.3. The sums of protein output, lipase output, and juice flow evoked by different concentrations of CCK-PZ in the group of rats fed at 1 degrees C for 3 weeks were almost identical to the corresponding value in the group fed at about 21 degrees C for 3 weeks.4. The sum of output of zymogen protease in the former group was almost identical to the corresponding value in the latter group except that the sum induced by 20 m-u. CCK-PZ/ml. was significantly larger in the former.5. The sum of output of amylase induced by various concentrations of CCK-PZ in the former group was significantly smaller than the corresponding value in the latter group.6. It was thus concluded that the CCK-PZ-induced outputs of protein, lipase, and zymogen protease were little affected if any by 3 weeks of cold exposure, whereas the CCK-PZ-induced amylase output was significantly suppressed.7. Another similar series of experiments was performed in the summer of the same year. The results obtained suggest that the secretory function of exocrine pancreas is directly inhibited by prolonged cold exposure in summer but it is not in autumn.


Effect of visual experience on tubulin synthesis during a critical period of visual cortex development in the hooded rat.

1. In some species, restriction of visual experience in early life may affect normal functional development of visual cortical cells. The purpose of the present study was to determine if visual deprivation during post-natal development in the hooded rat also affects the production in brain cells of certain molecular components such as tubulin, that are needed for growth and maintenance of synapses and neurites. 2. Norwegian black hooded rats were reared under a variety of conditions of visual deprivation. At various stages of development the animals were killed and the rate of synthesis of tubulin in visual and motor cortex determined. Tritiated colchicine was used to assay tubulin and L-[14C]leucine injected into the brain ventricles 2 hr before death was used to measure rate of tubulin synthesis. 3. In rats reared in normal light there is a marked elevation in visual cortex tubulin synthesis that spans the period from eye-opening (13 days) until approximately 35 days. This elevation in tubulin synthesis is absent in animals reared in darkness from birth or deprived of pattern vision by eyelid suture. Also the effect of visual deprivation on tubulin synthesis was specifically confined to visual cortex and was not found for the motor cortex. Similarly, the incorporation of L-[14C]leucine into total protein in visual cortex was unaffected by dark rearing. Hence the stimulation of tubulin synthesis by visual experience in rat visual cortex is not attributable to a general non-specific stimulation of protein synthesis. 4. Rats that were dark-reared from birth and then exposed to a lighted environment for 24 hr during a certain critical period that extends from eye-opening (13 days) until approximately 35 days, displayed a significant increase in visual cortex tubulin rats that were brought into the light later than 35 days showed no significant increase in tubulin synthesis when compared with their continuously dark-rearer controls. 5. It is suggested that the number of synapses and cytoplasmic processes that a developing cell can maintain depends on the size of the tubulin pool available to that cell. Tubulin in brain only has a half-life of about 4 days, so when the level of tubulin drops this could result in competition between different synapses for the limited supply of tubulin needed for their maintenance, a factor which may contribute to the structural plasticity of the visual cortex during the critical period.


The influence of chloride ions on renal outer medullary cell volume.

1. Slices of rat renal outer medulla have been incubated in media made hyperosmotic (540 and 1055 m-osmole/kg H2O) by the addition of urea, and containing variable concentrations of Cl (90, 144, 189 and 215 mM) and constant concentrations of Na (180 mM) and K (5.9 mM). A small number of incubations have been conducted in the presence of 100 mM-Na. 2. Changes in cell volume during incubation have been calculated on the basis of initial and final slice weight and inulin space. 3. The capacity of cells to shrink in response to extracellular osmotic stress was related principally to the external Cl concentration rather than to osmolality, increases in concentration being associated with enhanced shrinkage. Shrinkage was accompanied by net loss of cellular Cl. The ratio between intra- and extracellular Cl concentration (ca. 0.41) remained constant in all media. 4. In media containing low Cl concentration (90 mM), reduction of media Na concentration to 100 mM enhanced shrinkage. This effect was not observed when medium Cl concentration was greater than 90 mM. 5. Ethacrynic acid-cysteine (1 mM) significantly impaired the shrinkage response to extracellular osmotic stress, and caused cell swelling in media of relatively low Cl concentration and osmolality. It did not abolish the dependency of cell volume upon Cl concentration. There was marked reduction in the net amount of Cl lost from cells. 6. Ethacrynic acid-cysteine caused an increase in cellular Na content only in media containing 540 m-osmole/kg H2O and Cl concentrations less than 215 mM. 7. Ouabain (1 mM) inhibited cell shrinkage to a lesser extent than ethacrynic acid-cysteine in all media except that causing the greatest shrinkage under control conditions (215 mM-Cl/1055 m-osmole/kg H2O). It is suggested that a ouabain-sensitive process may play an increasingly important role in Cl-related cell shrinkage as this becomes more pronounced. 8. The findings are consistent with the view that Cl ions influence cell volume both through their effective external osmotic pressure and by means of Cl-specific process; the latter is associated with net loss of cellular Cl. A dependence of this loss upon Na/k exchange-linked metabolism is inferred, but the present findings do not permit the active or passive nature of the extrusion to be defined.


The relative importance of thermal, osmotic and hypovolaemic factors in the control of drinking in the pig.

1. The influence of thermogenic, osmotic or hypovolaemic stimuli on drinking has been measured in young pigs. Temperature changes in the hypothalamus and spinal cord were induced by means of implanted thermodes, while peripheral changes in skin and scrotal temperature were induced by circulating water through a coat. Osmotic stimuli were applied by I.V. injections of NaCl and hypovolaemia was induced by withdrawal of blood. 2. At an ambient temperature of 21--24 degrees C warming the hypothalamus for 10 min increased the water intake approximately 40%, while cooling the hypothalamus for a similar period reduced it by about 70%. 3. At an ambient temperature of 21--24 degrees C warming the scrotum caused the pigs to drink more than controls, and at the higher ambient temperature of 32 degrees C the effect was even greater. 4. Warming or cooling the spinal cord produced effects that were not consistent either within or between animals, thus temperature changes in this region play, at most, a minimal physiological role in the control of drinking in the pig. Warming the skin to 40 degrees C produced a slight increase in water intake, as also did cooling of the skin. 5. Drinking induced by an osmotic stimulus was proportional to the concentration of NaCl ranging from 5 to 30%. 6. Withdrawal of 500 ml. blood did not produce a statistically significant increase in water intake compared with controls.


[3H]gamma-Aminobutyric acid uptake into neuroglial cells of rat superior cervical sympathetic ganglia.

1. The influx of [3H]gamma-aminobutyric acid ([3H]GABA) into isolated rat superior cervical ganglia has been measured by radioassay, supplemented by autoradiography. Ganglia were incubated in oxygenated Krebs solution at 25 degrees C, containing 10 microM-amino-oxyacetic acid. Under these conditions more than 95% of accumulated tritium was unmetabolized [3H]GABA. 2. Ganglionic radioactivity increased linearly with incubation time, to yield an intracellular fluid/extracellular fluid concentration ratio (Ci/Co) of about 200 after 6 hr in 0.5 microM-external [3H]GABA. 3. Uptake showed saturation with an apparent transport constant (KT) of 6.8 microM and maximum influx velocity (Jmaxi) of 7 mumole 1. cell fluid-1- min-1. 4. The influx rate at Co = 0.5 microM was unaltered by raising intracellular GABA from 0.2 to 1 mM. 5. Influx velocity increased with temperature (5--35 degrees C) in a monotonic manner with an apparent activation energy of 14 kcal mole-1. 6. Concentrative uptake was depressed by reducing external [Na+] with ouabain, by raising [K+]o above 20 mM, or by removing external Cl-. Uptake was not particularly sensitive to Ca2+ or Mg2+ ions. 7. Utake of [3H]GABA (0.5 microM) was inhibited by beta-guanidinopropionic acid (apparent KI, 28 microM), beta-alanine (KI, 55 microM), gamma-amino-beta-hydroxybutyric acid (KI, 220 microM), beta-amino-n-butyric acid (KI, 708 microM), 3-aminopropanesulphonic acid (KI, 832 microM) and taurine (KI greater than 1 mM). Uptake was not depressed by 1 mM-glycine, alpha-alanine, leucine, serine, methionine or alpha-amino-iso-butyric acid. 8. Radioactively labelled methionine, leucine, glycine, serine, beta-alanine and taurine (concentrations less than or equal to 5 microM) were also taken up by ganglia. Of these, only uptake of beta-alanine and taurine were significantly depressed by 1 mM-GABA. 9. Autoradiographs confirmed that [3H]GABA and [3H] beta-alanine were taken up predominantly into extraneuronal sites (presumed to be neuroglial cells). Methionine, leucine, glycine and serine showed preferential accumulation in neurones. Neuronal uptake of leucine was not prevented by inhibiting protein synthesis. 10. Calculations of net fluxes from unidirectional tracer fluxes suggest that the sympathetic glial cells are capable of promoting net uptake of GABA at external concentrations above 1 microM.


The reversible replacement of internal potassium by caesium in isolated turtle heart.

1. By perfusing the isolated turtle heart with Cs solution, most of the intracellular K can be replaced by Cs. After 3--4 hr, Cs approaches a steady-state distribution with a concentration slightly below initial K concentration. 2. During the initial stages of perfusion, the heart accumulated Cs and lost K, the exchange ratio of K for Cs was estimated to be about 0.6. Subsequently perfusion yielded an equi-ionic substitution of K by Cs. 3. In presence of DNP (2 x 10(-4) M), K efflux and Cs accumulation increased but the low initial K--Cs exchange was abolished. Then, the replacement of K by Cs took place at a ratio of K:Cs of about 0.8. Ouabain (10(-5) M) suppressed uptake of Cs whereas K loss was the same as with DNP. 4. These results confirm that permeability of the cardiac sarcolemma to Cs is low, and suggest that the movement of Cs must be mainly attributed to its active transport into cells by the ionic exchange which normally transports K+ and is coupled to the extrusion of Na. The initial low net K efflux could be explained by an accumulation process which facilitates retention of K by the heart. A mechanism of this kind would be described as active reabsorption of some K present in extracellular space and would consequently reduce the uptake of Cs. 5. After loading the heart with Cs, perfusion with K solution showed the exchange of Cs for K at a ratio of Cs:K of about 0.5. K reaccumulation is reduced by ouabain (10(-5) M) and comes back to a normal steady-state distribution after 5 hr. At this time, K concentration was slightly below normal K value, but only half Cs content was eliminated. After 15 hr of perfusion, intracellular K remained constant whereas 15% of the original Cs remained.


The electrical responses of the rabbit rectococcygeus following extrinsic parasympathetic nerve stimulation.

1. The responses of the rabbit rectococcygeus muscle to stimulation of the extrinsic pelvic nerves have been investigated using intracellular micro-electrode recording techniques. 2. Submaximal pelvic nerve stimulation evoked a depolarization (e.j.p.) which was graded with stimulus strength and abolished by atropine (10(-6) g/ml.) and tetrodotoxin (TTX). 3. Single supramaximal stimuli evoked action potentials associated with muscle contraction. 4. In the presence of atropine, to abolish the e.j.p.s, supramaximal stimulation of the pelvic nerves evoked hyperpolarizations (i.j.p.s) which were graded with stimulus strength and abolished by TTX. 5. The transmitter responsible for the i.j.p.s is unknown. Phentolamine (10(-5) g/ml.) and propranolol (3 x 10(-5) g/ml.) in concentrations which block respectively alpha and beta adrenoceptors and the adrenergic neurone blocking agent guanethidine (10(-6) g/ml.) were ineffective in blocking the inhibitory response. 6. It is concluded that stimulation of the pelvic nerves to the rectococcygeus releases two transmitters, acetylcholine, responsible for the e.j.p. (and muscle contraction) and a non-adrenergic non-cholinergic transmitter which is the basis for the mechanical relaxation.


gamma-Aminobutyric acid efflux from sympathetic glial cells: effect of 'depolarizing' agents.

1. Isolated desheathed rat superior cervical ganglia were incubated in [3H]2,3,-gamma-aminobutyric acid ([3H]GABA) solution (1--10 microM for 2--3 hr) in the presence of 10 microM-amino-oxyacetic acid (AOAA). The subsequent efflux of tritium into a stream of superfused non-radioactive GABA-free Krebs solution at 25 degrees C was measured. 2. In the presence of 10 micrometer-AOAA the mean basal efflux rate coefficient (k0) for exit of tritium into the superfusion fluid was 0.7 x 10(-3) min-1. More than 98% of effluent tritium comprised unchanged [3H]GABA. The rate coefficient showed no correlation with the amount of [3H]GABA previously accumulated by the ganglion. 3. Elevation of [K+]o to greater than 50 mM increased the rate coefficient for [3H]GABA release by up to four times. Changes in efflux rate were not correlated with osmotic changes, and persisted after re-accumulation of effluent [3H]GABA by the inward carrier was inhibited. The effect of alkali metal cations diminished in the order Rb+ greater than K+ greater than Cs+Li+. Effects of K+ solutions were not reduced by omitting Ca2+ ions, with or without the addition of Mg2+. 4. Application of electrical pulses (0.1--1 msec duration, 1--10 Hz, 4 min trains) to the ganglion soma or to the preganglionic nerve trunk also raised k0. This effect declined with repeated stimulus trains, without an accompanying diminution in the response to K+. Responses to electrical stimulation were not reduced by amethocaine (300 microM), tetrodotoxin (3 microM) or raised [Mg2+i1 (0 mM-[Ca2+]/30 mM-[Mg3+]). Separate local superfusion of the pre- and post-ganglionic nerve trunks and of the ganglion soma showed that the response to electrical stimulation was localized to the vicinity of the stimulus and was not propagated along the nerve trunks or across the synapses. 5. Electrical recording from impaled 'inexcitable' cells (presumed to be neuroglial cells (Appendix)) indicated that the quantities of K+ ion accumulating during repetitive nerve stimulation are insufficient to stimulate the release of GABA from the glial cells. No physiological role for the release process in modulating neuronal excitability could be adduced.


Excretion, accumulation and site of synthesis of urea in the snail Pila globosa during active and dormant periods.

The pattern of urea excretion in active and dormant phases of the amphibious Indian apple snail, Pila globosa, as well as the possible site and mechanism of urea synthesis in this animal have been studied. 1. Urea may be synthesized in the hepatopancreas of this snail and excreted through the nephridia with the nephridial fluid during the active period of the animals life. In dormant snails, this metabolic excretory waste accumulates in its various organs and body fluids. 2. The possibility of the presence of an ornithine cycle for the synthesis of urea in the hepatopancreas is indicated in this snail.


[Electromyographic study of uterine activity in the castrated red fox (Vulpes vulpes L.) treated with oestradiol and progesterone (author's transl)].

Effect of oestradiol and progesterone on the electromyographic activity (EMG) of the uterus is studied in 6 groups of 2 previously castrated vixens (A, B, C, D, E, F). The animals of gropu A are treated daily with intramuscular injections of oestradiol benzoate alone or oestradiol and progesterone together. These hormones are also given to the group F, oestradiol by a subcutaneous tablet and progesterone intramuscularly. The other females only receive a silastic implant of oestrogen (groups B, C, D, E). Electrical activity is daily recorded during the various treatments, in unanaesthetized animals, by means of platinum electrodes permanently implanted in the uterus. Plasma oestradiol concentrations in peripheral blood are determined in groups A and B. The results show that : 1. OEstradiol induces rhythmic EMG activity composed of bursts of action potentials (Fig. 2). It appears after a delay of 1 to 3 days following the beginning of treatment, except in the animals of group E, treated with a 25 mg oestradiol implant (6 days). Then, EMG activity gradually increases, and the frequency of bursts is at a maximum within 24 to 48 hours. Except in group E, it exceeds 30 per 10 minutes and the amplitude of potentials sometimes reachs 1 mV.


Arterial blood pressure and heart rate changes during self-stimulation by dogs in the basal forebrain region, lateral preoptic area, hypothalamus, ventral midbrain and amygdala.

In dogs pressing a lever for a brain-stimulation reward, arterial blood pressure (ABP) was elevated for 20 out of 24 sites tested, but this effect was usually conspicuous only at twice the threshold current sustaining stable performance. Hypertension was seen only in one ventral tegmental and two hypothalamic sites. In three anterior placements the ABP and heart rate (HR) increased more upon a fixed ratio than on continuous reinforcement. In most sites, self-stimulation was accompanied by cardiac acceleration; however, in some placements the HR was similar to or even less than control values. Continuous stimulation (5-10 sec) at one nucleus accumbens and four hypothalamic sites by the experimenter was aversive and produced a clearcut pressor response. The cardiovascular changes seem to depend on a spread of current to brain centres controlling circulatory functions and also, to some extent, on the animal's motor activity. The results contradict the claim that a causal relationship exists between the autonomic concomitants of self-stimulation and the intrinsic nature of the brain-stimulation reward.