Surface modification of guinea pig sperm during in vitro capacitation: an assessment using lectin-induced agglutination of living sperm. Plant lectins have been used to advantage to study carbohydrate-containing cell surface receptors in numerous systems. In this study, a simple, reliable assay was developed to quantitate lectin-induced agglutinability of sperm. This assay was used successfully to compare some of the surface properties of uncapacitated and capacitated guinea pig sperm. Capacitation was induced by incubating sperm in minimum capacitation medium (MCM) or modified Tyrodes solution (T-PL). Control incubations were done in Ham's F-10 or Hank's balanced salt solution which do not support capacitation. At timed intervals during incubation, sperm samples were assessed for pattern and degree of lectin-induced agglutination. Results establish that: (1) soybean agglutinin (SBA) and to a lesser extent concanavalin A (Con A) induced agglutinability of guinea pig sperm increase during in vitro capacitation in MCM; (2) a similar increase in SBA induced agglutinability occurs during capacitation in T-PL, but not in the non-capacitating media; and (3) for sperm incubated in MCM or T-PL, there is a significant increase in tail to tail agglutination after capacitation. The results with SBA demonstrate that D-galactose and/or N-acetyl-D-galactosamine containing receptor sites or the guinea pig sperm surface are affected by capacitation, and this effect occurs, at least in part, in the sperm tail. Possible explanations for the observed increase in agglutinability are discussed. The agglutination assay may prove useful as a direct test for the occurrence of capacitation and may be especially valuable for species having a small acrosome or limited number of eggs.


Uptake of Ca2+ is one of the earliest responses to fertilization of sea urchin eggs. Sea urchin eggs take up Ca for 10 min following insemination (determined as uptake of 45Ca from the SW (3)). Although 90% of this uptake occurs after the beginning of the cortical reaction and may represent external binding of Ca to the egg surface coats, there is a brief phase of uptake (o-30 sec) which precedes the cortical reaction; this may represent a Ca flux into the eggs.


Insect cellular differentiation. I. Redifferentiation of the adult labial glands of Manduca sexta (Lepidoptera). With the exception of a few primitive ephemeropterans, winged insects do not normally molt as adults, although they can molt under appropriate hormonal conditions. We investigated this supernumerary molt process by taking adult labial glands (from Manduca sexta), cutting them into fragments of a single cell type, implanting them into individual freshly molted pupae, and then recovering them from pharate adult and adult hosts. The appearance and function of these fragments were compared to those of normally metamorphosing glands. Based on these criteria: (1) the supernumerary adult molt involved cellular de- and re-differentiation and (2) no transdifferentiation occurred, between the separate adult gland cell types.


Development of the compound eyes of dragonflies (Odonata). II. Development of the larval compound eyes. The development of the compound eye was analyzed by marking individual ommatidia and by studying naturally occurring pigment band patterns. New ommatidia are added to the eye along its anterior margin. This changes the directions of view of the older ommatidia with the greatest change occurring in the fovea. New ommatidia are added to the fovea medially, and old ones are removed laterally as their interommatidial angles and directions of view in the visual field change. Over one-third of the aeshnid ommatidia are foveal during at least one of the early larval instars, and are then used for peripheral vision later in development. The design of each ommatidium is a compromise so that it is adapted for all stages of development, but sometimes better adapted for one instar than for others. Factors which are balanced for best vision are lens diameter, facet admission function, interommatidial angle, and inclination of the optic axis to the eye surface. Ommatidia are described in terms of these factors throughout their life history, from initial differentiation anteriorly, through passage through the fovea, to their final relatively posterior location.


Development of the compound eyes of dragonflies (Odonata). III. Adult compound eyes. The distribution of ommatidial diameters and interommatidial angles, as determined by measuring the angles between the optic axes of adjacent ommatidia, are mapped across the surface of the compound eyes of a variety of species selected for different adult behaviors, developmental histories, and taxonomic positions. The size of the visual fields, prey capture foveas, foveas composed of large dorsal ommatidia, and other specializations in the numbers of ommatidia that view various directions in the visual field are discussed in relation to adult behavior. Advanced species have less resemblance between their larval and adult eyes than primitive species. In contrast to their larvae, adults increase the monocular resolution of each eye at the expense of binocular vision. Most species have foveas which view in approximately the anterior direction, instead of in a region of binocular overlap, and many species have foveal bands which view along the horizon. Some advanced perching species, which approach their prey and other odonates from below, have an additional vertical foveal band that views along a vertical plane from the anterior direction to a more dorsal direction. The most unusual foveal band is seen in active flying species. The large dorsal ommatidia of the migratory Anax junius, which cover approximately one third of the eye surface, view a narrow region of the visual field that extends along a plane from the most lateral direction of one eye to a dorsal direction, and continues without interruption to the most lateral direction of the other eye.


Identification of eight-cell tw32 homozygous lethal mutants by aberrant compaction. Early cleavage stage (4- and uncompacted 8-cell) embryos from experimental (+/tw32 X +/t32) and control (male +/tw32 X female +/T) matings were recovered at 56 hours post coitum, cultured, separated into uncompacted and compacted 8-cell embryo groups, and either analyzed histologically for cytoplasmic lipids or cultured through the morula-to-blastocyst transformation. Abnormal compaction was associated with excess cytoplasmic lipids at the 8-cell stage (P less than 0.01). Also, 89.2% (33/37) of the original uncompacted experimental embryos underwent developmental arrest characteristic of tw32 homozygous lethals. Thus, aberrant compaction, a newly reported symptom of the tw32/tw21 syndrome, affords a visual means to identify tw32 homozygotes at 8-cell stages.


In vitro inhibition of mouse dental development by tetracycline. Embryonic molars and incisors were dissected from mandibles of 15-day post-fertilization C57BL/10 mouse embryos and were cultured in vitro for six days on agar-solidified Eagle's basal medium. Experimental explants were cultured on medium which was the same as the control except that 50, 75 or 100 microgram/ml tetracycline was added. Treated explants of both incisors and molars were suppressed in development and reduced in size. Enamel organs and dental papillae of all tooth germs subjected to higher tetracycline concentrations were abnormal in structure and differentiation of ameloblasts and odontoblasts was inhibited. Explants treated with higher dosage levels of the drug were more severely affected than those exposed to lower concentrations. Recovery from the suppression induced by tetracycline was observed in explants transferred to control medium for four days of growth following treatment. Differentiated ameloblasts and odontoblasts observed in the recovering tooth germs indicated that the inhibition in development was temporary. The results of this study showed that tetracycline can alter dental development in vitro prior to mineralization. The observed inhibition may be related to a disruption of collagen biosynthesis which is thought to play a role in the controlling epithelial-mesenchymal interaction involved in tooth germ morphogenesis.


Development of the compound eyes of dragonflies (Odonata). IV. Development of the adult compound eyes. The changes in the directions of view of marked larval ommatidia were observed after the emergence of the adult. Those ommatidia that had been present during the first larval instar had the most posterior directions of view in the adult visual field while the newest ommatidia that had not been functional for vision in the aquatic larva contributed to the anterior and dorsal foveas of the aerial adults. The changes in interommatidial angles at emergence are discussed. Contrary to the general trend for interommatidial angles between retained larval ommatidia to decrease at emergence, the interommatidial angles in the larval fovea of aeshnid visual predators increase at emergence. The modifications in an odonate compound eye at emergence are like an exaggeration of the modifications that occur at the moult from one larval instar to the next, except that the newest ommatidia do not have any compromises in their design for use in the aquatic vision of the larvae. This is in contrast to the ommatidia retained from the earliest larval instars which have to have the most compromises in their design so that they can be adapted for the visual requirements of every larval instar, as well as the adult. This is discussed in relation to the trend among advanced species of odonates to replace the larval ommatidia by an entirely new set of adult ommatidia.


Effects of puromycin and actinomycin D on fertilized rabbit eggs cultured in vitro. Rabbit zygotes were cultured in media containing varying concentrations of puromycin and actinomycin D in order to determine what effect these agents have on events of fertilization and early development. Concentrations of puromycin greater than 10(-5) M inhibited mitosis, cytokinesis of fertilized eggs and leucine incorporation. In approximately 50% of the zygotes treated with puromycin (10(-5) M or greater) the female pronucleus remained at its site of formation, the cortex, and did not migrate centrad. In these instances the male pronucleus moved from its site of development to the female pronucleus. Concentrations of actinomycin D greater than 10(-7) M also inhibited mitosis and cytokinesis of fertilized eggs. Breakdown of the nuclear envelopes and association of the paternally- and maternally-derived chromatin did not occur in either puromycin- or actinomycin D-treated embryos. Actinomycin D at all of the concentrations employed (10(-9) to 10(-4) M) had little effect upon the structure of nucleolus-like bodies within male and female pronuclei. Male and female pronuclei of puromycin (10(-4) M) and actinomycin D (10(-5) M) treated zygotes, incubated with tritiated thymidine and prepared for scintillation counting and autoradiography, synthesized DNA at a reduced level when compared to control specimens. Although "side effects" of puromycin and actinomycin D treatment are not excluded, these results suggest that nascent proteins may be required for events of fertilization.


Penetration of the zona-free or intact eggs by foreign spermatozoa and the fertilization of deer mouse eggs in vitro. Zona-free eggs were introduced to fresh or preincubated sperm suspensions and the penetration of eggs by foreign spermatozoa was examined, as evidenced by enlargement of the sperm head and formation of the male pronucleus. It was found that zona-free hamster eggs can be penetrated by guinea-pig, deer mouse and rabbit spermatozoa but zona-free rat, mouse and rabbit eggs cannot be penetrated by guinea-pig spermatozoa. Furthermore, zona-free rat and mouse eggs cannot be penetrated by spermatozoa from two species of deer mice and the Mongolian gerbil. The zona pellucida of a few intact rat eggs can be penetrated by mouse (6%) and by P. leucopus spermatozoa (14%) but enlargement of the sperm head and formation of pronuclei were observed in the former but not in the latter. It seems that (1) sperm capacitation is required for the penetration of zona-free eggs, (2) the attachment of foreign spermatozoa to eggs may indicate their potential ability of penetration in some cases, (3) there is a certain affinity between the vitellus of one species and spermatozoa from another species, (4) the block to the entry of foreign spermatozoa is not only in the zona pellucida but also in the vitelline membrane, (5) zona-free hamster eggs can be penetrated by spermatozoa of six species, (6) mouse spermatozoa can penetrate zona-free eggs of three species, and (7) fertilization of intact P. maniculatus eggs can be achieved in vitro.


Chick somite determination: the role of factors in young somites and the segmental plate. One class of hypotheses proposed to explain the anterior to posterior sequence of chick somite formation envisions the movement of morphogenetic substances or processes along the segmental plate prior to somite formation. An effort was made to demonstrate any such phenomena in the region of somite formation by placing grafts that contained forming somites into the segmental plates of cultured host embryos. No somite-inducing properties on the part of the grafts were detected. Host somite formation proceeded in a normal manner. In additional experiments, posterior portions portions of segmental plates were isolated from the more anterior parts of the segmental plate which might contain the hypothetical morphogenetic factors. It was found that anterior portions of the segmental plate representing as many as eight prospective somites could be removed without impairing the ability of the remaining posterior portion to form somites in vitro. It is concluded that other hypotheses of the type studied here are not likely to be useful and that the present data further strengthen the argument that the cells of the chick segmental plate present at any time between the 8- and 20-somite stages of development are committed to form somites. In addition, the explant experiments described here indicate that a somite pattern representing about 11 prospective somites, becomes established in the segmental plate.


Serum protein depletion by cultured rat embryos (1). Cultures of 10-day rat embryos depleted a protein band with a molecular weight of approximately 125,000 from the rat serum medium. Delayed centrifuged serum differed from immediately centrifuged serum by a reduction in the staining intensity of the 125,000 molecular weight protein band and by the absence of two high molecular weight (greater than 200,000) protein bands.


Localization of mouse Pgk-2 gene at the D end of the H-2 complex (1). A survey of the Pgk-2 alleles carried by H-2 congenic lines of mice has established that the Pgk-2 locus is near the D end of the H-2 complex on chromosome 17. A comparison among inbred strains of the alleles for Pgk-2, H-2, and two other genes in this vicinity, Tla and Ce-2, has revealed a remarkable correlation suggestive of strong linkage disequilibrium in the wild mice from which the inbred strains were derived.


Urea levels in plasma and erythrocytes of the southern fiddler skate, Trygonorhina fasciata guanerius. Plasma and erythrocyte samples from Trygonorhina fasciata guanerius were analysed for urea content. The erythrocyte urea concentration is higher than plasma urea concentration. The difference in concentration is probably due to the presence of urea normally bound to protein within the erythrocyte. Erythrocyte urea concentrations followed environmentally induced changes in plasma urea concentrations. Naturally occurring plasma urea concentrations, exceeding 500 mMolar, are some of the highest recorded for an elasmobranch.


High levels of inosine monophosphate in the erythrocytes of elasmobranchs. The acid soluble organic phosphates of the erythrocytes of three species of elasmobranchs were assayed by chromatography on Dowex 1 anion exchange columns. Organic phosphates in the peaks eluted from these columns were identified by their ultraviolet absorption spectra and by further chromatography on paper. All three species are unusual amongst the vertebrates in that their erythrocytes contain high levels of inosine monophosphate (IMP). IMP has little effect on the oxygen affinity of the hemoglobins of the two species tested.


Base composition, size and sequence similarities of genoma deoxyribonucleic acids from clinical isolates of Pseudomonas putrefaciens. The mean base compositions of DNA from 27 strains of Pseudomonas putrefaciens, P. rubescens and P. piscicida ranged from 43-4 to 53-2 mol% GC with genome sizes from 3.04 X 10(9) to 4.23 X 10(9) daltons. On the basis of in vitro DNA-DNA binding, estimated spectrophotometrically from initial renaturation rates, P. putrefaciens strains were heterogenous in the extent to which they shared similar nucleotide sequences, and were divided into four DNA homology groups. The DNA characteristics of strains in these groups correlated with several biochemical characteristics that facilitated identification of clinical isolates of P. putrefaciens. The two species P. putrefaciens and P. rubescens appear to be synonymous and none of the four groups of P. putrefaciens was related in DNA sequences to P. pisicida. Pseudomonas putrefaciens should theretofore be retained as a single species and characteristics for identifying the various groups within the species are listed.


The effects of temperature and growth rate on the proportion of unsaturated fatty acids in bacterial lipids. The effects of temperature and growth rate on the fatty acid composition of the extractable lipids of four mesophilic and three psychotrophic bacteria were examined. Two of the mesophiles (Escherichia coli and Pseudomonas aeruginosa) increased the proportion of unsaturated fatty acids in their lipids with decreasing temperature over their whole growth temperature range. The other mesophiles (Enterobacter aerogenes and Lactobacillus casei) increased the proportion of unsaturated fatty acids with decreasing temperature only over the lower half of their growth temperature ranges. The psychrotrophs Pseudomonas fluorescens and Enterobacter sp. had a constant proportion of unsaturated acids over the lower half of their growth temperature range, while the psychotrophic Lactobacillus sp. showed no consistent change in its unsaturated fatty acid composition with temperature. All species showed some variation of unsaturated fatty acid composition with growth rate at the highest and lowest growth temperatures, although such variations were small in some species (Ent. aerogenes and Lactobacillus sp.).


Use of canonical variates analysis in differentiation of bacteria by pyrolysis gas-liquid chromatography. Low-resolution pyrolysis gas-liquid chromatography (p.g.l.c.) can differentiate genera of aerobic food spoilage bacteria. Multivariate statistical techniques were applied but neither principal components nor furthest neighbour cluster analysis produced a consistent differentiation although both confirmed the reproducibility of p.g.l.c. When the distance between genera was redefined in terms of Mahalanobis D2- a generalized concept taking into account scatter around the mean-good differentiation was observed and could be displayed graphically by plotting the genus group means relative to the first two canonical variate axes. The coefficients of the canonical variates provide a strategy for discriminating between the genus groups. Some practical problems in the identification of unknowns using this technique are discussed.


Trypanosoma (Schizotrypanum) dionisii: effect of various agents on attachment and entry to macrophages in vitro and on morphogenesis. The attachment and entry of Trypanosoma dionisii to mouse peritoneal macrophages in vitro were studied. Both occurred to a similar extent whether parasites were alive or heat-killed, and whether macrophages were obtained from normal or immunized mice. Attachment occurred equally at 4 and 37 degrees C, but entry only occurred at the higher temperature. Neither was affected by pretreatment of parasites with active or inactivated complement. Entry, but not attachment, was inhibited by cytochalasin B; both were inhibited by trypsin. Immune mouse plasma (if inactivated) stimulated attachment but not entry (within 24 h). It also stimulated intracellular replication of T. dionisii by multiple fission and subsequent differentiation (probably within macrophages) to small extracellular trypomastigotes. No extracellular parasite and only scanty intracellular forms survived 120 h in cultures containing non-inactivated immune mouse plasma. It was concluded that attachment (in the absence of antibody) occurred to non-specific receptors in the macrophage membrane and was followed by phagocytosis of the parasites rather than their active penetration of the cell.


Abnormalities of the sciatic nerves of dystrophic mice with reference to the large U-axons. A statistical study using regression analysis was used to evaluate the density of axonal organelles in dystrophic peripheral nerves. The slope of the density of neurotubules (NT) in myelinated (M-) axons was different from that in small unmyelinated (U-) axons. The slope of the density of NT in large U-axons (larger than 1.5 micron in diameter) was similar to that of the M-axons in both the dystrophic and control mice. There was a higher density of NT in the dystrophic M-axons than in the controls in the anterior, posterior and mixed nerves of the sciatic nerve. There was also a higher density of NT in the dystrophic small U-axons than in the controls. There was a higher density of neurofilaments (NF) of M-axons in the dystrophic mice than in the controls. On the contrary, the NF of small U-axons were lower in density in the dystrophic mice. These results were different from our previous reports, which were observed in the distal part, depending on when the groups of U-axons were divided (Okada, Mizuhira and Nakamura 1976a).


The incorporation of isotopes into proteins of normal and dystrophic mouse heart and skeletal muscle. Studies are described of L-[3H-(G)]leucine and [5-3H]uridine incorporation into proteins in dystrophic mouse skeletal and heart muscle of the 129/Rej/dy Bar Harbor strain. The results show a remarkable difference in isotope incorporation in the 2 muscle types. While skeletal muscle in the dystrophic mouse shows a consistently high cytoplasmic incorporation of leucine and uridine respectively, the heart muscle shows a marked reduction of uptake in nuclear, myofibrillar, and cytoplasmic protein. These findings appear to suggest that in terms of protein synthesis the mouse heart is not affected at the age of 8 weeks by a recognizably similar dystrophic process to that in the skeletal muscle. Whilst our material showed no gross evidence of cardiomyopathy, cytomorphometric analysis of the dystrophic heart muscle is in keeping with an atrophic process. The possibility that this difference in protein synthesis pattern may be related to an embryologically different organogenesis of the heart and skeletal muscle altering the predystrophic synthesis pattern cannot be excluded.


Determination of glial fibrillary acidic protein (GFAP) in human brain tumors. Brain tumors have been tested for their glial fibrillary acidic protein (GFAP) content by means of the rocket electrophoresis technique. Meningiomas and neurinomas were low in GFAP. Metastases had a low level of GFAP except when contaminated with surrounding tissue. Non-nervous tumors such as myeloma, myeloplaxoma and adenocarcinoma gave negative results. More detailed correlations with histological observations have been looked for in glial tumors. Low levels of GFAP were always associated with signs of malignancy such as mitoses and giant or atypical cells, whereas high levels of GFAP were correlated with the presence of well-preserved astrocytes.


Defective neutrophil function in myotonic dystrophy. Polymorphonuclear leukocytes (PMNs), obtained from 10 patients with myotonic dystrophy and 39 age-matched controls, were tested for chemotactic activity, chemiluminescence (CL), and phagocytosis. PMNs from 8 of the 10 patients had depressed chemotactic indexes (30 +/- 23) as compared to controls (61 +/- 18) (P less than 0.0003), and 6 of the 10 patients' PMNs produced lower peaks in CL (less than 90%) than those of controls. Phagocytosis and bactericidal activity were evaluated in 7 patients and were normal. Control PMNs incubated in patient serum produced normal chemotactic activity and CL. These results indicate defects in 2 PMN membrane-associated activities in myotonic dystrophy and suggest that the PMN is affected by the generalized membrane abnormality underlying myotonic dystrophy.


Susceptibility of human skeletal muscle culture to influenza virus infection. I. Cytopathology and immunofluorescence. We found that fused human muscle in culture supports neurotropic influenza A viral infection, as demonstrated by viral growth experiments, hemadsorption, observation of cytopathic changes and detection of intracellular viral antigen. The time of peak virion production and the appearance of cytopathic effects in these experiments were similar to previously described characteristics in influenza A-susceptible organotypic cultures of other tissues. Cytopathological changes occurred earlier in mononucleated cells than in myotubes and included cell-rounding; cytoplasmic retraction, granularity and vacuolization; ribonucleic acid-containing cytoplasmic inclusions; nucleolar enlargement; and clumping of chromatin. Immunofluorescent staining demonstrated early nuclear fluorescence, followed by spread of viral antigen into the cytoplasm. A subpopulation of mononucleated cells, shown by cloning studies to be myoblasts, showed no cytopathic effects or evidence of intracellular viral antigen and was presumably resistant to neurotropic influenza A infection. The adverse effects of influenza A on fused human muscle cells in tissue culture contrast with the inability of the virus to replicate in skeletal muscle after animal inoculation in acute experiments. Therefore, host factors may affect attempts to produce an animal model of human muscle disease with this virus.


Quantitative studies of dorsal root ganglia and neuropathologic observations on spinal cords in familial dysautonomia. Intrauterine development and postnatal maintenance of dorsal root ganglion neurons are abnormal in familial dysautonomia, an autosomal recessive disorder associated with autonomic, motor and sensory deficits. Normally, dorsal root ganglion weight increases with age. This does not occur in the cervical plexus ganglia of dysautonomic patients. Neurons in dorsal root ganglia are found to be markedly diminished in the youngest patients and slow degeneration causes further depletion with age. Quantitative studies on C8 dorsal root ganglia show the normal neuron content to be between 42,500 and 53,600. In 3 patients with familial dysautonomia the range was 4,090-8,590 with the smallest number being in the oldest patient. Lateral root entry zones and Lissauer's tracts are severely depleted of axons. In older patients loss of dorsal column myelinated axons becomes evident and is first seen in lumbar fasciculus gracilis, cervical fasciculus cuneatus and interfascicular fasciculus. Temperature sensation is markedly impaired from infancy in familial dysautonomia. Loss of pain sensation is prominent and worsens with age.  Vibration sense diminishes in adolescence and coordination of limb movements becomes poor in older patients. Neuron depletion in dorsal root ganglia and the progressive pattern of cord changes correlate well with these clinical observations.


Hypertrophic Charcot-Marie-Tooth disease. Light and electron microscope studies of the sural nerve. Sural nerve biopsies from 15 patients with hypertrophic Charcot-Marie-Tooth disease have been studied by light and electron microscopy. There is a considerable variation in size of onion bulbs in patients from different kinships but the appearances were similar in patients from the same kinship. Comparison of sural nerve biopsies from patients within the same kinship suggests that with increasing age there is a progressive reduction in myelinated fibre density, an increased number of fibres undergoing demyelination and an increased frequency of onion bulb formations. Motor conduction velocities were reduced in all patients and were inversely proportional to the number of onion bulb lamellae, and to the proportion of demyelinated fibres found on sural nerve biopsy. Abnormalities of unmyelinated fibres were present in all the nerves studied. There was a relative increase in the density of denervated Schwann cell subunits and collagen pockets. The findings suggest that unmyelinated fibres undergo degeneration in the disease and lend some support to the hypothesis that the primary abnormality may be neuronal.


Period of risk for recurrence in medulloblastoma. Ninety-nine patients with medulloblastoma who received surgery and radiotherapy, and had a statistically sufficient follow-up period were analyzed for factors influencing survival and the relevance of the "period of risk for recurrence" hypothesis. This postulate states that the period of risk for recurrence of a congenital tumor is equal to the age at presentation of illness plus 9 months' gestational time. The assumption is made that a tumor of embryonic origin will become manifest after a period of time determined by its inherent rate of growth and that tumor cells surviving treatment will multiply and present with recurrence in an equal period of time. Ten of 43 patients survived the period of risk, a presumed cure rate of 23%. None of these patients has subsequently developed evidence of tumor recurrence. Older patients at initial surgery had a somewhat greater survival rate for the first 5 years after treatment (10 of 26 older patients (38%) versus 15 of 54 younger patients (28%)), but by 10 years there was no appreciable difference in survival rates between those over 16 years of age and those younger. The beneficial effect of total neuraxis megavoltage radiotherapy is indicated by the improved 5-year survival rate from 9 of 41 patients (22%) to 16 of 39 patients (41%) with the newer techniques.


Mannitol dose requirements in brain-injured patients. There is little information as to the optimal use of mannitol. To determine the dose-response relationship, the osmotic gradient required, and the time course of intracranial pressure (ICP) reduction produced by mannitol, eight patients with acute head injury were studied in whom ICP was monitored with a ventriculostomy and found to be elevated. Ventilation was controlled to a pCO2 of 25 +/- 3 mm Hg and all were paralyzed with Pavulon. None had received barbiturates. Before mannitol administration the intracranial volume-pressure response was determined. Mannitol was administered as a bolus of 0.25 gm/kg, 0.5 gm/kg, and in six patients, 1 gm/kg, separated by at least 8 hours. In all patients the ICP reduction with 0.25 gm/kg (41.3 +/- 10.2 mm Hg leads to 16.4 +/- 5.6, p less than 0.01) was equivalent to that achieved with the larger doses. Serum osmolality rises of 10 mOsm or more were associated with a reduction in ICP. Much smaller doses than those previously recommended were effective in reducing the ICP acutely, although at 5 hours there was a trend toward persistent reduction when the larger dose is used. This trend was small and indicates that smaller and more frequent doses are as effective in reducing the ICP while avoiding the risk of osmotic disequilibrium and severe dehydration.


Time course of vasospasm in man.

Time course of vasospasm in man. Measurements were made at eight predetermined positions on 627 sets of angiograms from 293 patients with aneurysms. A ratio between the sum of the vessel diameters in the subarachnoid space to the sum in the base of skull and neck was calculated and plotted against time. Vasospasm has its onset in man about Day 3 after subarachnoid hemorrhage, is maximal at Days 6 to 8, and is gone by Day 12. There is a tendency for patients in poor clinical grades to have more vasospasm. The patients with most vasospasm have a significantly higher mortality than those with the least.


Intercellular granules and vesicles in prolonged cerebral vasospasm. Prolonged vasospasm was produced in the dog basilar arteries by introduction of fresh arterial blood or norepinephrine into the chiasmatic cistern. Myonecrosis was limited to a small number of smooth-muscle cells, and a large number of muscle cells appeared intact. The most characteristic change was the appearance of aggregated granules and vesicles in the widened extracellular space between smooth-muscle cells, particularly near the adventitia and the elastic lamina. The granules were spherical, 50 to 100 nm in diameter, often surrounded by a single membrane, and contained a dense osmiophilic core, about 40 to 90 nm in diameter. In addition, the elastic lamina often became loose and corrugated or broken.


The mega cisterna magna.

The mega cisterna magna. Eleven cases of enlarged cisterna magna were found in a series of 3000 computerized tomography scans. We believe mega cisterna magna by itself is not related to any specific symptoms and may not require further study or treatment.


Sacral rootlet rhizotomy at the conus medullaris for hypertonic neurogenic bladder. Three patients with spastic neurogenic bladder underwent sacral root stimulation and appropriate section of motor rootlets to the detrusor at the levels of the conus medullaris. Compared to the results obtained with rhizotomies at the sacral levels in a previous series of patients, urinary frequency and infection were inhibited for longer periods of time, but some uninhibited bladder activity recurred in all three patients. Analysis of anatomical and electrophysiological data serves to emphasize the complexity and asymmetry of efferent supply to detrusor muscle. The authors conclude that the role of selective rhizotomy for inhibition of the spastic bladder is inconclusive, and perhaps a combination of surgery and medications that inhibit smooth-muscle contraction may be required for long-term protection of urinary collection systems.


Carotid endarterectomy. Temporal profile of the healing process and effects of anticoagulation therapy. The healing of the canine carotid endarterectomy was defined at intervals from 30 minutes to 3 months after surgery by means of angiography, light microscopy, and scanning electron microscopy. Immediately after flow was established, a fibrinplatelet carpet formed on the endarterectomized surface. A typical thrombus formed on this initial layer resulting in vessel occlusion in 52% of non-heparinized animals. By 48 hours after surgery, there was little evidence of active thrombus formation, and reendothelialization from existing endothelial cells was noted. One week later, most of the mural thrombus had disappeared and re-endothelialization was well underway; by 3 months after surgery, re-endothelialization was complete. Intraoperative heparinization resulted in a striking reduction in mural thrombus formation and 100% patency rate. Vessel closure with vein-patch grafts resulted in no improvement of vessel patency. However, the results of this aspect of the study cannot be totally extrapolated to human carotid endarterectomy for the reasons discussed. The survival of the vein-patch grafts was investigated.


Effect of dexamethasone on cerebral edema from cranial impact in the cat. A Remington humane stunner was used to deliver blows to the skulls of anesthetized cats. Alternate animals were post-treated with either dexamethasone (4 mg/kg/day) or a comparable volume of saline. Each animal was tested for cerebral edema 48 hours after impact by measurement of the change in density of white matter from normal values. Dexamethasone therapy did not reduce the change in density of hemispheres with contusions involving both cortex and underlying white matter. For hemispheres with contusions limited to cerebral cortex, there was minimal edema of the white matter, which was reduced a slight amount by dexamethasone.


Enflurane anesthesia and changes of intracranial pressure. Enflurane has been recommended by some as an ideal agent for use in neuroanesthesia. There is no statistically significant alteration of normal intracranial pressure with enflurane anesthesia. However, supporting a clinical impression, this study demonstrates in dogs that enflurane will significantly increase an already elevated intracranial pressure.


Effects of laminectomy on spinal cord blood flow. The effect of a one-segment (L-2) laminectomy on spinal cord blood flow (SCBF) was determined by the reference sample method using isotope-labeled microspheres. The SCBF was measured before laminectomy (control) and at 15 minutes postlaminectomy with the dura exposed (Series 1), 1 hour postlaminectomy with the laminectomy site closed (Series 2), 24 hours postlaminectomy with the laminectomy site closed (Series 3), and 24 hours postlaminectomy with the dura exposed (Series 4). With the laminectomy site open, SCBF was significantly depressed (22% to 45%) along the entire length of the spinal cord at 15 minutes postlaminectomy. At 1 hour postlaminectomy (with the laminectomy site closed), SCBF approached control values, although areas with significantly lowered flow were still observed in all portions of the spinal cord. By 24 hours postlaminectomy, SCBF had returned to prelaminectomy levels. However, if within 1 hour preceding the 24-hour SCBF measurement, the laminectomy site was reopened, SCBF tended to fall at and caudad to the laminectomy site. These data indicate that laminectomy can cause a significant decline in SCBF. At the present time, the mechanism(s) for this laminectomy-induced depression of SCBF are unknown, although a temperature-induced vasoconstriction is suspected.


Hyperemia, CO2 responsiveness, and autoregulation in the white matter following experimental spinal cord injury. The authors present the results of a controlled, randomized study of alterations in spinal cord blood flow, CO2 responsiveness, and autoregulation following experimental spinal cord injury in cats. Permanent paraplegia is shown to be associated with persistent hyperemia, loss of CO2 responsiveness, and impaired autoregulation in the white matter at the injury site. Probable mechanisms underlying these changes in spinal cord vasomotor control are discussed. Marked similarities between vascular responses of injured spinal cord and luxury perfusion of the brain are pointed out.


Obliterative arachnoiditis complicating lumbar spinal stenosis. The authors report five patients with spinal stenosis who had a total myelographic block at the level of the obliterated subarachnoid space. Arachnoiditis had not been considered as a primary diagnosis until laminectomy revealed a non-pulsating, thickened dural sac that conformed to the internal configuration of the involved spinal canal. Two patients had stenosis complicated by spondyloarthrosis over multiple lumbar levels, one had a previous spinal fusion, another had degenerative spondylolisthesis, and the fifth had a large midline extruded disc at L2-3 that completely blocked the spinal canal. The dura was opened in two patients, confirming the lesion. Despite obliteration of the subarachnoid space, significant relief for approximately 1 year followed decompressive laminectomy, foraminotomy, and discectomy, with disappearance of neurogenic claudication in three patients. Postoperative erect films showed no caudad passage of contrast. While further observations are required, an awareness of this complication of spinal stenosis is important in the diagnosis and management of such patients and in evaluating their ultimate prognosis.


Congenital inclusion dermoid cyst of the anterior fontanel. An unusual type of dermoid cyst is reported in 10 African infants. In these cases a soft, cystic mass located over the anterior fontanel was noted shortly after birth and gradually enlarged. The cyst had no intracranial extension and was easily excised intact. The clinical and x-ray findings of the cyst are described and compared with the usual dermoids. The histology and the contents of the cyst are detailed and some peculiarities of this lesion pointed out.


Mucoceles with intracranial and extracranial extensions. Report of two cases. Two cases of unusual childhood mucocele are presented. These serve to illustrate the great potential these lesions have for slow, insidious development and insinuation of themselves into regions of the head and face where they are difficult to remove surgically. A description of the staged surgical excision is presented to emphasize the importance of radical removal of these benign lesions.


Progressive neurological dysfunction secondary to postoperative cervical pseudomeningocele in a C-4 quadriplegic. Case report. A case is detailed of a patient who developed progressive neurological deficit above a fixed quadriplegic level at C-4 18 years after posterior cervical decompression for trauma. Diagnostic evaluation revealed a pseudomeningocele at the site of his previous surgery. Subsequent operative closure resulted in reversal of his neurological symptoms.


The angiographically occult cerebrovascular malformation. Report of three cases. Three cases presenting with hemiparesis, headache, or seizures gave no history suggestive of subarachnoid or intracerebral hemorrhage. Carotid arteriograms were performed, and in each case failed to demonstrate a vascular malformation. In all three cases cerebral lesions were shown by either computerized tomographic (CT) scan, radionuclide scan, or both. Surgical exploration and biopsy revealed a vascular malformation in each case. The CT scans in two of the cases showed dense lesions that could suggest vascular malformation as a diagnostic possibility.


Cervical myelopathy due to spondylosis. Case report. The authors report the case of a patient with cervical myelopathy who was examined at autopsy 2 years after a second anterior cervical fusion by Cloward's technique. The clinical course and pre- and postoperative myelograms are presented. Theories as to the etiology of myelopathy are discussed. This case demonstrates chronic changes that seem to implicate a vascular theory but not the specific vessel or vessels. The mechanism of improvement following the Cloward procedure is not explained by the pathological slides.


Effects of erotic stimuli on male aggression toward females. In order to examine the effects of highly erotic films on aggression toward females, male subjects were first either angered or treated in a neutral manner by a male or female confederate. After viewing a highly erotic film or a neutral film, subjects were given an opportunity to both aggress against and reward the confederate. Erotic films were found to increase aggression overall, but there was no indication of differential aggression as a function of sex of target. Results for physiological arousal, however, suggested that aggression was possibly inhibited for subjects exposed to an erotic film and paired with a female. Various suggestions for future lines of research based upon the notion of inhibition are offered, as well as suggestions regarding the sexual arousal and aggression relationship.


Aggression-inhibiting influence of sexual humor. Forty-eight undergraduate males participated in an experiment designed to investigate the hypothesis that prior exposure to sexual humor would reduce the level of aggression directed by angry individuals against the person who had previously provoked them. In order to examine this suggestion, subjects were first angered or not angered by a male confederate; next, exposed to either neutral, nonhumorous pictures or to one of two types of sexual humor (nonexploitative, exploitative); and finally, provided with an opportunity to aggress against this individual by means of electric shock. Results indicated that exposure to exploitative sexual humor, but not exposure to nonexploitative sexual humor, significantly reduced the strength of subjects' later attacks against the victim. These findings are discussed in terms of the results of a follow-up study suggesting that individuals are more likely to think or fantasize about exploitative than nonexploitative sexual humor following the removal of such stimuli.


Control of respiration as a means of controlling responses to threat. After a 30-minute rest period, (a) subjects in a respiration tracing condition began replicating their breathing patterns from the rest period; (b) subjects in an attention tracing condition participated in a comparable task that did not involve the control of respiration; and (c) subjects in a no-tracing condition were not assigned to perform any task. After the tracing manipulation was introduced, half of the subjects were assigned to a threat condition and informed that they would receive a series of painful electric shocks, whereas the other subjects were assigned to a no-threat condition and informed that they would receive red light stimulation. Analyses of heart rate and self-report data indicated that (a) the threat manipulation was effective; (b) controlling respiration did not reduce subjects' stress responses; and (c) subjects in the no-tracing condition were the only stressed subjects to show decreases in physiological arousal over time, an effect that may have been due to their use of a cognitive coping strategy (situation redefinition). These findings do not provide evidence that control of respiration is an effective strategy for controlling stress but do suggest that, when not interferred with, subjects can employ relatively effective, self-generated cognitive coping strategies.


The effect of anaesthesia on pentagastrin stimulated gastric acid secretion in the cat. 1. The effect of Saffan (alphaxalone and alphadolone acetate) and Nembutal (pentobarbitone) anaesthesia on gastric acid secretion stimulated by I.V. bolus injections of pentagastrin was investigated in the gastric fistula cat. The effect of Saffan anaesthesia was also tested on I.V. near-maximal and sub-maximal infusions of pentagastrin. 2. Neither anaesthetic reduced the acid secreted in response to bolus injections of pentagastrin. Increased acid secretion with the anaesthetic was noted at some doses of pentagastrin in both intact and vagotomized animals. 3. Saffan anaesthesia had no effect on near-maximal gastric acid secretion stimulated by pentagastrin 8 microgram kg-1 hr-1 but increased the response to pentagastrin 1 microgram kg-1 hr-1. 4. It is suggested that the differences in the acid secretory responses of the anaesthetized acutely prepared animal compared with the conscious animal are a consequence of the surgical procedures rather than the state of consciousness.


The morphology of group Ia afferent fibre collaterals in the spinal cord of the cat. 1. The enzyme horseradish peroxidase (HRP) was injected into single Ia muscle afferent fibres in anaesthetized cats. Subsequent histochemistry allowed the morphology of the axons and their collaterals in the lumbosacral spinal cord to be determined. 2. Fifteen Ia axons were stained, four from medial gastrocnemius, four from lateral gastrocnemius-soleus and seven from muscles innervated by the posterior tibial nerve. All thirteen axons that could be traced into the dorsal roots bifurcated upon entering the cord. Between 4 and 11 mm of axons were stained and they gave off eighty seven collaterals over distances between 3 and 9 mm. Collaterals were given off at intervals of 100-2600 micron at an average spacing of about 1000 micron. 3. All Ia collaterals had a characteristic morphology. After leaving the parent axon they ran ventrally to lamina VI and then ventrolaterally to the motor nuclei. The collaterals coursed cranially from their point of origin to the motor nuclei so that their lamina VI terminations were about 100-300 micro caudal to their terminations in motor nuclei. Terminal arborizations were limited to three sites; lamina VI (the intermediate region), lamina VII (the Ia inhibitory interneurone region) and lamina IX (the motor nuclei). The three sets of terminals had characteristic arborizations and bouton arrangements. 4. The results are discussed in relation to previous anatomical studies. In particular the present results suggest that a single Ia collateral makes contact with many more motoneurones than has previously been suggested in fact with fifty to sixty rather than with about ten.


Hepatic portal vein infusion of glucose and sodium solutions on the control of saline drinking in the rat. 1. Rats were prepared under anaesthesia with non-occlusive catheters in hepatic portal vein (HP) and inferior vena cava (VC) and maintained under standard conditions. 2. Each rat received a series (3 day intervals) of 30 min infusions of different solutions or sham into HP or VC. Oral intake of 0.15 M-NaCl and water were measured for 30 min. Significant change in drinking behaviour was assumed when the response to HP infusion differed from both sham and VC infusion. 3. Saline drinking was inhibited by HP infusion of 1 M- or 2M-NaCl, an effect blocked by right vagotomy or by addition of 16 mM-KCl to the infusate. 4. Saline drinking was increased and water drinking decreased by HP infusion of 2 M-glucose but not sucrose or fructose. 5. Saline drinking was decreased by HP infusion of deoxy-D-glucose to inhibit glucose utilization or ouabain to inhibit (Na4-K+) ATPase. 6. Results are consistent with the presence of afferent nerve terminals in hepatic portal vessels which are sensitive to change in NaCl or glucose concentration and which, in response thereto, alter drinking behaviour. The effects of NaCl and glucose on the discharge rate of the nerve terminals may be interpreted in terms of changing activity or electrogenicity of a Na pump but changes in membrane conductance or Na influx cannot be ruled out.


The effect of age upon the influx of glucose into the brain. 1. Rats aged from 1 to 116 weeks were studied. 2. Influx of glucose into the brain is low in suckling rats but rises after weaning, to reach its highest level in the young adult, thenceforward declining slowly as age increases. 3. The blood-brain barrier for glucose is fully developed in the rat by the age of 18 days and glucose enters the brain, at this stage, by carrier-mediated transport, as in the adult. 4. The results show that the low influx of glucose into the brain of the suckling animal is due to a low maximum rate of transport of glucose rather than to a low affinity of the carrier-molecule for glucose. 5. In the young adult rat, efflux of glucose back from the brain into the blood is greater than in either the suckling or the old animals. Thus the margin of safety, i.e. the extent to which the blood glucose can be reduced without affecting the utilization of glucose by the brain, is highest in the young adult. 6. The lower margin of safety in the suckling animals is compensated for by the high influx of the ketone bodies which provide an alternative source of energy at this age. In the old animals there is no alternative source of energy, so that the older brain is at greatest risk in hypoglycaemia.


Effect of exogenous noradrenaline on local cerebral blood flow after osmotic opening of the blood-brain barrier in the rat. 1. The regional penetration into the brain of exogenous labelled noradrenaline (following unilateral injection into the internal carotid artery) was correlated with the effect of this amine on regional cerebral blood flow as measured by the [14C]ethanol technique in anaesthetized rats. 2. A hyperosmolar solution of urea was injected into the ipsilateral internal carotid artery to induce osmotic opening of the blood-brain barrier. 3. The extent of the blood-brain barrier damage was followed by macroscopic and fluorescence microscopic visualization of systemically injected Evans blue, and by the determination of the brain uptake index for noradrenaline. 4. The extravasation of Evans blue was restricted to the brain areas nourished by the internal carotid artery on the same side as the injection. 5. The normally low penetration of noradrenaline into the brain was enhanced fourfold in those brain regions that showed Evans blue extravasation following the administration of hypertonic urea. 6. In the same regions, the systemic administration of noradrenaline markedly increased local cerebral blood flow, compared to the contralateral hemisphere that was unaffected by the injection of urea. This effect on regional cerebral blood flow was blocked by the beta-receptor antagonist, propranolol.


Voltage sensitive calcium channels in the presynaptic terminals of a decrementally conducting photoreceptor. 1. Intracellular recordings were made from the presynaptic regions of the photoreceptors of the median ocellus of the giant barnacle, Balanus nubilus.2. Millivolt changes in membrane potential near the dark resting level in the terminals elicit post-synaptic activity and consequently must be sufficient to modulate transmitter release from these endings.3. In normal saline the terminal voltage usually changes in a graded manner to increasing intensities of illumination of the cell. When the terminal region is superfused with saline containing TEA, 3-AP or high concentrations of K, an all-or-none action potential can be elicited consistently by light or injected current.4. The peak value of this action potential depends on the Ca concentration in the saline. The action potential can be generated if Sr or Ba ions replace Ca, but is reduced or blocked if Mg, Co, or Mn ions are added to the saline. It is virtually unaffected by TTX or replacement of Na with TMA ions in the saline. These results suggest that Ca carries most or all of the inward current during the action potential.5. The action potential is followed by a large undershoot which can last several seconds. The amplitude and duration of the action potential and the duration of the undershoot all grow in increasing concentrations of TEA up to 400 mM, the highest concentration tested. The threshold for the action potential decreases as the concentration of TEA is increased to 10 mM; increasing the concentration further has no effect on the threshold. These observations suggest that TEA blocks a voltage-sensitive potassium conductance at low concentrations but has less effect on the current responsible for the undershoot.6. Electrophysiological and pharmacological evidence suggests that the Ca channels are concentrated in the presynaptic terminals of this photoreceptor.


Membrane currents in cat myocardium: separation of inward and outward components. 1. The single sucrose gap method was used to control the membrane potential of cat ventricular fibres.2. Following the early rapid events (capacitive, Na and slow inward (si) current spikes) the membrane current on depolarization contained three time-dependent components which appeared attributable to the inactivation of I(si) and the activation of two outward currents labelled I(K) and I(x).3. Tail currents were analysed with a view to confirming these conductance changes. At -60 mV the tail progressed from being predominantly inward in direction after short (30-50 msec) depolarizations to being predominantly outward after long (> 300 msec) depolarizations. Inward and outward components decayed exponentially with time constants independent of previous membrane history. The Q(10)s were about 3.4. Experiments with D600 and variations of the driving force identified the inward tail component (tau approximately 55 msec at -60 mV) as I(si). The major outward tail component (tau approximately 300 msec) appears to be carried primarily by potassium. A second outward tail component (tau approximately 3 sec) of much smaller amplitude than I(K) was observed after long depolarizations and is tentatively labelled I(x).5. Membrane currents at 0 mV can be described as the sum of three exponential processes: I(si) inactivation (tau approximately 90 msec), I(K) activation (tau approximately 370 msec) and I(x) activation (tau approximately 3 sec). Conductance measurements (envelops of I(si) and I(K) tails) supported these time courses. I(si) time constants increased from 50 msec at -40 mV to 120 msec at +40 mV. I(K) time constants increased from 400 msec at -40 to about 520 msec at -25 mV before declining to 300 msec at +40 mV.6. I(si) amplitudes measured visually (difference between peak I(si) and current level after 200-500 msec) were compared with those measured graphically (semilog plots, subtraction of I(K) and I(x)). As a consequence of the relative amplitudes and time courses of I(si) and I(K), the shapes of the I(si) voltage relations were not markedly different: visual estimates at 200 msec were in agreement with graphic estimates, visual estimates at 300 or 500 msec exceeded these by 15-30% between -20 and +20 mV.


The potassium current underlying delayed rectification in cat ventricular muscle. 1. Outward currents in cat ventricular fibres have been studied using the single sucrose gap method. The time dependent outward currents can be separated into a fast component, I(K), and a slow component, I(x). The voltage dependence of the I(K) time constant was bell-shaped, being about 150 msec at -90 mV, 500 msec at -25 mV and 300 msec at +30 mV. The combination of much faster time constants and larger amplitudes relative to I(x) allowed the estimation of I(K) amplitude, but not time course, from semilog plots of membrane currents accompanying 2 sec depolarizations.2. The ;steady-state' outward current at 2 sec (I(ss)) was separated into time independent background current (I(bg)) and time dependent I(K). The activation threshold for I(K) was about -50 mV and its amplitude increased steeply between -30 and +10 mV. The ratio of I(bg) to I(K) was about 1 between -30 and +30 mV.3. The current-voltage relations of I(ss) and I(bg) showed inward going rectification but negative slope regions were not observed. Raising the external K concentration from 3 to 10, 20 and 30 mM increased conductance and induced ;cross-overs' in the current-voltage relations. Increases in conductance were offset by the reductions in driving force, i.e. currents at plateau potentials were not larger in high K solutions.4. K accumulation occurs in response to prolonged membrane depolarization but conductance rather than accumulation appears to be responsible for the slowly rising outward current, I(x). However, the accumulation which takes place during the activation of I(x) may preclude an accurate determination of its time course and reversal potential.5. The potential at which outward I(K) tails declined to zero was strongly dependent on external K concentration in the range 3-30 mM. Inward going I(K) tails were difficult to detect because control hyperpolarization from the resting potential triggered large inward time dependent currents. Evidence is presented suggesting that much of this time dependency is due to the depletion of extracellular K from regions of restricted diffusion.6. The steady-state activation variable (n(infinity)) of the I(K)-system had to be calculated from isochronic (300 msec activating pulses) activation relations and tau(n)s because shifts in V(K) due to K accumulation precluded complete activations. The shape of n(infinity) was sigmoid approaching 0 at -60 mV, 0.5 at -20 mV and 1 at +20 mV.7. The fully activated current-voltage relation of I(K) displayed inward going rectification.8. It is concluded that there are strong similarities between I(K) in ventricular muscle and i(x1) in Purkinje fibres. Possible counterparts in frog atrial muscle include the currents labelled I(1) and i(x.slow).


The effect of membrane cholesterol on the sodium pump in red blood cells. 1. Human red blood cells (R.B.C.) were incubated with phosphatidylcholine vesicles to obtain partial depletion of their membrane cholesterol. The kinetic parameters of the Na pump (affinities and maximal fluxes) were determined in these cells and compared with controls. 2. In the presence of internal K, progressive cholesterol depletion induces gradually (i) an increase of the maximal flux (ii) a reduction of the apparent affinity for internal Na. 3. In the absence of internal K, cholesterol depletion has no apparent effect, indicating that the observed changes were mediated by the internal K. Cholesterol depletion acts by increasing these two K effects: (i) activation of the maximal fluxes, and (ii) reduction of the internal Na affinity. 4. The cholesterol effect (on the K-pump interaction) is specific; it occurs without any change (i) in the affinities for internal Na and inorganic phosphate and for external Na and K, and (ii) in the number of pumping sites. 5. Under physiological conditions, cholesterol reduces the cation translocation rate and increases the selectivity of the pump for internal Na.


The dynamic behaviour of photoreceptor cells in the fly in response to random (white noise) stimulation at a range of temperatures. 1. Photoreceptor cells in Calliphora stygia were stimulated with randomly fluctuating green light while the resulting fluctuations in membrane potential were recorded with intracellular micro-electrodes. 2. Fourier analysis was used to obtain the frequency response functions between the light intensity fluctuations and the membrane potential fluctuations at a range of different temperatures. 3. The results show that for small light fluctuations the transducer function can be modelled by a cascade of five identical linear exponential filters whose time constants decrease as the temperature of the cell is increased. 4. The time constants of the linear filters and their rate of change with temperature are similar to the electrical behaviour of cell membranes. However, a series of chemical reactions with similar activation energies could also explain the observed behaviour. 5. Evidence is presented that the total light response is a linear summation of discrete waves of depolarization (bumps), which become longer in duration but of constant area as the temperature is reduced.


Lability of renal papillary tissue composition in the rat. 1. The acute effects of (a) a minor operative procedure using ether as the anaesthetic, and (b) the administration of 0.9% saline as a single I.V. injection in the conscious rat, on renal tissue composition were studied in hydropenic and normally hydrated rats. 2. The operative procedure and anaesthesia induced a rapid and transient decrease in papillary osmolality in both hydropenic and normally hydrated animals, the important contributing factor being a significant decrease in urea content. 3. Administration of a small volume of saline caused a rapid decrease in urea content, and an increase in water content. 4. It is concluded that papillary composition is extremely labile, large changes being produced by relatively minor experimental procedures.


The effects of artificial lung inflation on reflexly induced bradycardia associated with apnoea in the dog. 1. The cardiac effects of artificial inflation of the lungs were studied during reflexly induced apnoea and bradycardia in anaesthetized dogs.2. Reflex apnoea and bradycardia were induced (a) by stimulation of the larynx with water or by electrical stimulation of afferent fibres in the superior laryngeal nerve, or (b) by combined stimulation of the superior laryngeal nerve and carotid body chemoreceptors.3. During combined stimulation of the laryngeal and carotid body inputs, the activation of respiration normally evoked by chemoreceptor stimulation was inhibited whereas the chemoreceptor cardio-inhibitory reflex was facilitated leading to periods of temporary cardiac arrest.4. In spontaneously breathing animals and in those artificially ventilated, lung inflation invariably caused tachycardia.5. Rhythmic artificial inflation of the lungs during the apnoeic period produced by the laryngeal input or by a combination of the laryngeal and chemoreceptor inputs wholly or partly reversed the bradycardia. This occurred using lung inflation volumes within the range of the normal tidal volume and inflation pressures of less than 12 mmHg; the response was independent of the composition of the gas used for inflating the lungs, and occurred at constant P(a, O2) and P(a, CO2). Lung inflation carried out during a reflexly induced arrest of the heart immediately restarted the heart and was accompanied by an exaggerated sinus arrhythmia.6. Evidence is presented that the observed effects of artificial lung inflation are reflex in origin with the vagus nerves as the main afferent and efferent pathways.7. Electrical stimulation of the central end of the cut pulmonary branches of the thoracic vagosympathetic nerves also caused tachycardia and had the same effects as lung inflation in modifying the reflexly induced bradycardia.8. Some clinical implications of these results are discussed.


Stimulation of renin secretion and calcium efflux from the isolated perfused cat kidney by noradrenaline after prolonged calcium deprivation. 1. The effects of noradrenaline on the secretion of renin and on the efflux of Ca have been investigated in the isolated cat kidney perfused with Locke solution containing the alpha-adrenergic blocking agent, phenoxybenzamine, to block increases in renal vascular resistance. 2. Noradrenaline elicited a marked increase in renin secretion in the absence of any discernible alterations in renal arterial pressure, and prolonged perfusion with Ca-free Locke solution failed to depress noradrenaline-evoked renin secretion. 3. Noradrenaline caused an increase in the efflux of 45Ca from prelabelled kidneys perfused with Ca-free solution. Increasing the noradrenaline concentration produced graded increases in 45Ca efflux and renin release, and the peak rise in efflux preceded or coincided with peak renin secretion. 4. DL-Propranolol inhibited the increase in 45Ca efflux and renin release resulting from noradrenaline stimulation. 5. Electrical stimulation of the renal nerve enhanced 45Ca efflux and renin release from prelabelled kidneys perfused with noraml Locke solution. 6. These findings provide further support for the view that the process of catecholamine-induced renin secretion involves mobilization of Ca from a cellular site.


Secretion of a potassium-rich fluid by the secretory coil of the rat paw eccrine sweat gland. 1. It is already known that the rat paw eccrine sweat contains high K(+) (greater than 150 mM) and low Na(+) concentrations (less than 70 mM). The present study was intended to clarify the site of K(+) secretion within the sweat gland, namely, the duct or the secretory coil. In vivo paw sweat was first induced by systemic pilocarpine injection or nerve stimulation. Both K(+) and Na(+) concentrations were studied in relation to the sweat rate to determine indirectly whether there is ductal secretion or reabsorption.2. Both Na(+) and K(+) concentrations in paw sweat agreed with the previous studies but did not show any saturation-type flow dependence at the high sweat rate range.3. A method has been developed to isolate a single segment of the secretory coil and induce sweat secretion directly from it in an in vitro condition.4. In the presence of fresh serum (30%, preincubated for 30 min at 56 degrees C) in the incubation medium, stable secretory activity due to 10(-6)M-Mecholyl could be maintained for 40 min or longer. The primary sweat thus induced contained low Na(+) (30 mM) and high K(+) (160 mM) concentrations.5. In the secretory coil sweat in vitro, K(+) concentration decreased and Na(+) concentration increased as the secretory rate fell either spontaneously or after addition of atropine or cyanide.6. It remains to be studied whether auxiliary ductal secretion or reabsorption is present at low rates of sweating in the rat sweat gland.7. It was concluded that the secretory coil of the rat paw sweat gland is the major, if not the sole, site of K(+) secretion.


Protein digestion and absorption in the rat. 1. A randomly labelled 14C protein was synthesized in order to investigate the site and rate of digestion and absorption of dietary protein in the rat. 2. A liquid test meal consisting of protein and a non-absorbable marker, 51CrCl3, was administered to rats which were then sacrificed at intervals up to 4 hr after ingestion of the meal. Analysis of intestinal contents showed that as gastric emptying proceeded, the meal moved rapidly to the distal two thirds of the small intestine. 3. Protein digestion and absorption occurred predominantly in this area over a period of 1-2 hr. 4. Amounts of endogenous protein present in the small intestine never exceeded amounts of exogenous protein during maximum absorption of exogenous protein (0-1 hr). At later time periods (2-4 hr), however, more endogenous than exogenous protein was detected in the intestinal lumen. 5. It is concluded that the digestion and absorption of dietary protein is a rapid process, taking place in the distal two-thirds of the small intestine. Endogenous protein levels do not exceed exogenous protein levels until after the bulk of exogeneous protein is absorbed.


Aldosterone effects on renal metabolism. 1. Manometric studies of the sodium dependent oxygen consumption in rat kidney slices have failed to reveal any significant effect of aldosterone treatment, adrenalectomy or sodium diet on sodium diet on sodium metabolism. 2. However, ammonia release from kidney slices was significantly reduced following adrenalectomy and this decrease was influenced by aldosterone treatment. 3. The dose-response characteristic obtained for this aldosterone-stimulated ammonia release has been determined. 4. The effect of a high Na+ diet on the ammonia release has been studied. An initial decrease after 2 days may be associated with decreased endogenous aldosterone secretion. However, aldosterone (2.5 microgram/100 g body weight)injections into these high Na+ treated animals fails to restore the normal ammonia release. 5. The effects of aldosterone (2.5 microgram/100 g body weight), dexamethasone (2.5 microgram/100 g body weight) and corticosterone (2.5 microgram/100 g body weight) injections, in adrenalectomized rats, on ammonia release and tissue tyrosine aminotransferase activities have been compared.


Carbon dioxide and venous return and their interaction as stimuli to ventilation in the cat. 1. Respiratory responses were measured in forty-seven cats, made decerebrate or anaesthetized with pentobarbitone or chloralose-urethane, to changes in the level of CO(2) infused into the inferior vena cava via an external oxygenator circuit or to changes in the volume of venous return or to the inhalation of CO(2).2. No consistent difference was found between the respiratory response to the increase in the level of CO(2) infused or CO(2) inhaled provided that the volume of venous return during both sets of tests was held constant at normal levels.3. If the volume of venous return was increased and the level of CO(2) infused maintained at levels such that V(CO2) did not increase, ventilation increased with a fall in P(a, CO2), a response lying approximately on the isometabolic curve.4. If the volume of venous return and the level of CO(2) infusion were raised together, a spectrum of intermediate respiratory responses was obtained which reproduced all those seen in earlier papers, in muscular exercise or other hypermetabolic states.5. None of the steady-state respiratory responses was significantly affected by bilateral vagotomy or section of the sinus nerves, though sinus nerve section slowed the responses to infused or inhaled CO(2) and they were then less precisely controlled.6. Additional experiments indicated that where CO(2) was infused or inhaled, the effective stimulus to respiration was an increase in mean P(a, CO2) in proportion to the CO(2) added and that the respiratory response to CO(2) was enhanced by reduced blood volume. How the changes in venous return were sensed and affected respiration, remains unclear.7. These results may explain why previous workers have obtained exaggerated respiratory responses to the infusion of CO(2) and why respiration increases rapidly at the start of exercise and is then maintained at high levels without discernible change in the chemical stimulus in arterial blood.


The slowing of gastric emptying by proteins in test meals. 1. Test solutions containing either glucose, casein, partially hydrolysed gelatin or egg albumin, native or denatured, at concentrations up to 50 g/l. in 33 mM-trisodium citrate solution, were given by tube into the stomachs of nine subjects in volumes of 600 or 750 ml. 2. The volume of the test solution recovered from the stomach after 20 min was measured. 3. The greater the concentration of solute the greater was the volume of the test solution recovered. 4. Gram for gram, gelatin hydrolysate was equivalent to glucose in slowing gastric emptying. Casein was slightly more effective than glucose and native egg albumin was less effective than glucose. 5. The results were explained by assuming that the products of hydrolysis of proteins stimulated osmoreceptors in the walls of the duodenum. 6. The results were in line with the suggestion that proteins in food contribute to the slowing of gastric emptying in such a way that isocaloric amounts of carbohydrate and mixed protein have the same effect. 7. There was a strong correlation between the concentration of glucose giving a recovery of 400 ml. and the corresponding concentration of casein within-subject, but there was no such relationship for gelatin hydrolysate. It was concluded that the between-subject variability in the digestion of casein was small, that for gelatin hydrolysate was large.


Effects of dopamine analogues and antagonists on carotid body chemosensors in situ. 1. The effects of dopamine, its analogues and antagonists on the chemosensory discharges originating from carotid bodies in situ were studied in anaesthetized cats. 2. Intracarotid (I.C.) injections of 100 ng or more of dopamine produced transient depression of the frequency of carotid nerve chemosensory discharges. Short term (1-5 sec) complete inhibition was usually elicited by 2 microgram dopamine. 3. I.V. injections of dopamine also produced inhibition of chemosensory discharges, an effect observed with doses which were still too low to produce changes in systemic arterial pressure. Half-maximal inhibition (ID50) of chemoreceptors was elicited with a mean dose of 84 ng.kg-1. 4. I.C. and I.V. injections of apomorphine and amantadine also produced transient inhibition of chemosensory activity. Higher doses of these analogues of dopamine were needed to produce this effect, and the resulting inhibition usually did not silence the nerve discharges. Apomorphine inhibition was slightly more prolonged than that with dopamine. 5. Large doses of amphetamine and tyramine, inducers of dopamine release, did not produce inhibition of chemosensory discharges. 6. The effects of two classes of dopamine antagonists were tested. Dose-response curves for dopamine and apomorphine inhibition were displaced to the right by administration of phenothiazines (chlorpromazine and perphenazine) and butyrophenones (haloperidol and spiroperidol). In animals treated with perphenazine or spiroperidol, dopamine became a stimulator of chemoreceptor activity. 7. It is suggested that dopamine present in carotid body may operate as a modulator of chemosensory activity.


The rate of recovery of vision after early monocular deprivation in kittens. 1. Fifteen kittens were monocularly deprived of vision by suturing the lids of the right eye together for various periods of time at different ages. A simple behavioural technique was used to assess the immediate effects of the period of monocular deprivation on the visual acuity of the deprived eye as well as the time course of any subsequent recovery.2. The extent of the recovery of vision was measured under conditions where the animal was either forced to use its deprived eye by performing a reverse suture or where the animal had both eyes open after the initial period of monocular occlusion.3. The initial effects of monocular deprivation were graded in severity according to the age at which the deprivation was imposed, ranging from apparent blindness in animals deprived at 6 weeks of age to only a small loss of acuity in kittens deprived at 12 weeks of age.4. The effects of deprivation imposed from birth were particularly severe, leading to a temporary blindness. Nevertheless after a period of time that became progressively longer with increasing deprivation, all animals showed some recovery of pattern vision over the course of the next 2 or 3 months. The extent of this recovery became progressively less as the period of deprivation was prolonged. There was even some recovery of vision (an acuity of 2.5 cycles/deg) in animals that were deprived throughout the duration of the ;critical period' to 4 months of age.5. Direct comparison of the rate of behavioural recovery between animals that were reverse sutured with that of litter-mates that received binocular input after monocular occlusion to either 45 or 60 days of age proved to be remarkably similar, although the acuity that was eventually attained by the reverse sutured animals was always slightly higher.6. The recoveries observed after reverse suturing were reasonably well correlated with changes observed in the ocular dominance of visual cortical cells under similar circumstances.7. Although the recovery in these animals can be accounted for by the simple notion of a competitive interaction between the two eyes, the recovery observed in animals that had both eyes open after the initial period of deprivation cannot be so readily explained. Evidently there must be an additional non-competitive mechanism of recovery.


Neurones in cat parastriate cortex sensitive to the direction of motion in three-dimensional space. 1. On psychophysical grounds, Beverley & Regan suggested that in man different neural mechanisms mediate the binocular perception of movement in depth and the binocular perception of positional (static) depth. They proposed that the human visual pathway contains several neural mechanisms, each sensitive to a different direction of motion in space. These mechanisms compute the direction of motion from the relative speeds and directions of movement of the left and right retinal images.2. We have recorded from 101 units in area 18 of cat visual cortex, searching for neurones tuned to the direction of motion in three dimensions, with properties that could account for the proposed directionally tuned binocular motion detectors in man. The cat's left eye viewed one bar, while its right eye simultaneously viewed a second bar. Single units were stimulated by independently oscillating the bars from side to side. The apparent direction of movement in three dimensions was altered by varying the relative speeds of the bars and their relative directions of motion. The mean (positional) disparity of the bars could also be varied.3. For one class of neurone (twenty cells), binocular stimulation inhibited firing for trajectories parallel to the frontoparallel plane over a large volume of space. Strong firing was produced by oppositely directed bar movements. Some of these neurones were especially narrowly tuned to the direction of movement in depth, responding only to a range of 2-3 degrees , i.e. to moving bodies that would hit or only narrowly miss the cat. These cells emphasized the direction of movement at the expense of positional information.3. These units occurred in clusters. On the perpendicular penetrations in which they were found, they comprised a substantial majority of all cells encountered.5. For a second class of neurone (nine cells), binocular facilitation produced selective responses to objects moving along trajectories that missed the head.6. The two classes of neurone provide a basis for four proposed directionally tuned binocular motion detectors.7. A third class of neurone (seventeen cells) was selectively sensitive to movements parallel to the frontoparallel plane. There was strong binocular facilitation when the bars moved at the same speeds in the same directions: oppositely directed movements might be more than 100 times less effective. These neurones may signal positional disparity.8. These three classes of neurone cut across established categories. Only when both eyes were stimulated simultaneously with targets moving in different speeds and directions was it possible to demonstrate the binocular interactions described here.


Increase in efflux of inorganic phosphate during electrical activity in small non-myelinated nerve fibres. 1. The movements of labelled phosphate were measured in garfish olfactory and in rabbit vagus nerves at rest and during activity. 2. In garfish olfactory nerve kept in solutions with 120 mM-sodium and 0.2 mM-phosphate the fractional loss of 32P was 9.82 X 10(-4) min-1. Lowering the sodium concentration of the washing fluid decreased the efflux; lowering the phosphate produced a transient increase with subsequent return towards the efflux in 0.2 mM-phosphate. 3. Stimulation at 0.50 sec produced an extra fractional loss of 12 X 10(-6) impulse-1. At 1/sec the effect was larger; at 5/sec it was about the same as at 0.5/sec. 4. After stimulation the effect of activity disappeared exponentially with a time constant of 4.4 min. 5. Lowering the sodium decreased the extra efflux with stimulation, whereas changing the phosphate concentration did not much affect the extra efflux. 6. In rabbit vagus nerve kept in 154 mM-sodium and 0.2 M-phosphate the fractional loss of 32P was 4.91 X 10(-4) min-1. Lowering the sodium or the phosphate decreased the resting efflux. 7. Stimulation of the vagus nerve at 15/sec produced an extra fractional loss of 0.87 X 10(-6) impulse-1. 8. The extra efflux with stimulation seems to result predominantly from an increase in intracellular inorganic phosphate resulting from increased break-down of ATP after activity.


Modification of visual response properties in the superior colliculus of the golden hamster following stroboscopic rearing. 1. Visual response properties of superior collicular neurones were investigated in golden hamsters reared from birth to adulthood in a stroboscopic environment.2. In comparison to normally reared animals, there was a marked decrease in the incidence of directionally selective cells in the colliculus of the strobe-reared hamsters. This effect was apparent when directional selectivity was determined by either the null criterion or a statistical measure. The reduction in directionally selective cells was found in both superficial and the deep layers of the colliculus.3. Neurones in strobe-reared hamsters also exhibited a different speed preference distribution from that obtained for normal animals, in that more cells in the restricted hamsters responded only to slow velocities, and less were broadly tuned with regard to the speed of moving stimuli.4. In addition to the effects obtained in dynamic response properties, there were also changes in the static response properties of superior collicular neurones. These were an increase in the proportion of cells whose responses were not affected by changing the size of a stationary flashed stimulus, and a concomitant decrease in the number of cells demonstrating either partial or complete suppression when the size of a flashed stimulus exceeded the boundaries of the receptive field activating region. Furthermore, while all cells which responded to stationary stimuli in normal animals yielded only phasic responses to stimulus onset and/or offset, in the strobe-reared hamsters eight cells were encountered which responded in a sustained fashion to stationary spots.5. There was no indication of an increased responsivity in the restricted animals to strobe stimulation, even when a strobe rate identical to that employed in the rearing environment was employed.6. The results were interpreted as indicating a disruption of normal visual functional organization in the hamster's superior colliculus by an aberrant visual input during development.


The effect of disuse on cholinergic enzymes. 1. The effects of disuse on the activity of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) have been investigated in the sciatic nerve and leg muscles of the rat. 2. Disuse was produced by blockade of nerve conduction by repeated subperineurial injection of tetrodotoxin (TTX), and the effects were compared to those of denervation. 3. After 8 days of disuse there was no change in neural ChAT activity in the sciatic nerves, anterior roots or intramuscular terminals. By contrast, surgical section of the sciatic nerve resulted in a marked decrease of ChAT in the nerve terminals. 4. Similarly, after 8 days of disuse there was no change in neural AChE activity in the sciatic nerves or anterior roots. 5. AChE activity in the disused muscles decreased by more than 50%, which was comparable to the effect of surgical denervation. 6. These results indicate that disuse produced by TTX blockade of nerve conduction does not affect the cholinergic enzymes ChAT and AChE in nerves, but does lead to a significant decrease in muscle AChE.


Effect of prior visual experience on cortical recovery from the effects of unilateral eyelid suture in kittens. The reversibility of monocular deprivation was tested physiologically in twelve kittens which had received varying amounts of normal visual experience prior to unilateral eye closure. Recordings obtained from cells in cortical area 17 indicated that the effects of monocular deprivation are reversible in cats as old as 8 weeks if the animals have been allowed normal visual experience before eye closure.1. Four kittens had their right eyes closed at 3, 4, and 5 weeks of age. All animals were reverse sutured at about 8 weeks of age, and after 2 weeks forced usage of the deprived eye, each animal was tested physiologically for recovery. Single unit recordings revealed a consistent relation between the extent to which the effects of initial deprivation could reverse and the age of the animal at the time of this deprivation. Recordings from a fifth, 8 week old kitten, which had been monocularly deprived for 3 weeks, ensured that our shortest period of deprivation induces a severe deficit.2. Two kittens which were reared in the dark for 4 and 5 weeks before unilateral eye closure, failed to show substantial (greater than 20%) reversal when reverse lid-sutured at 8 weeks of age. This failure suggests that kittens having their eyes closed after normal experience show enhanced reversibility, at least in part, on account of their early experience and not necessarily because of shorter deprivation. A litter-mate of one of these kittens was allowed 9 days of normal vision after dark rearing and before lid suture. Recordings which were performed both before and after 6 days of reverse suture demonstrated a near total (85%) reversal in ocular dominance.3. Three animals, monocularly deprived after some normal experience, recovered substantial numbers of binocular cells after both eyes had been allowed to remain open. In one of these cats the effectiveness of monocular deprivation was confirmed physiologically before eye opening. These findings contrast with those of other workers who have failed to find many binocular cells in kittens that had been allowed to recover, with eye opening, from monocular deprivation which had lasted since birth.4. One kitten was reared for 2 weeks (3-5 weeks of age) with alternating monocular deprivation. Single unit recordings from this cat, which were made after four additional weeks of unilateral eye closure, revealed some cells which had resisted monocular deprivation and which responded strongly to stimulation of the deprived eye. Reverse suture in the same animal led to the recovery of many cells (36%), dominated by the initially deprived eye, but did not result in a reversal in ocular dominance.


Human muscle nerve sympathetic activity at rest. Relationship to blood pressure and age. 1. Recordings of multi-unit sympathetic activity were made from median or peroneal muscle nerve fascicles in thirty-three healthy subjects, resting in recumbent position. Simultaneous recordings of intra-arterial blood pressure were made in seventeen subjects. The neural activity, quantified by counting the number of pulse synchronous sympathetic bursts in the mean voltage neurogram (burst incidence), was plotted against the arterial blood pressure level and the age of the subjects. The effects of spontaneous temporary blood pressure fluctuations were studied by correlating different pressure parameters of individual heart beats to the probability of occurrence of a sympathetic burst and to the amplitude of the occurring burst.2. Between different subjects there were marked differences in burst incidence, from less than 10 to more than 90 bursts/100 heart beats. No correlation was found to interindividual differences in the arterial blood pressure level but there was a slight tendency for increasing burst incidence with increasing age.3. Irrespective of the magnitude of the burst incidence, the bursts always occurred more frequently during spontaneous transient blood pressure reductions than during transient increases in blood pressure. When, for each heart cycle, the occurrence of a sympathetic burst was correlated with different blood pressure parameters there was regularly a close negative correlation to diastolic pressure, a low correlation to systolic and an intermediary negative correlation to mean blood pressure. There was a positive correlation to pulse pressure and to pulse interval.4. When measured for individual heart beats, not only the occurrence but also the mean voltage amplitude of the sympathetic bursts tended to increase with decreasing diastolic pressure.5. In a given subject when comparing heart beats with the same diastolic pressure, the occurrence as well as the amplitude of the sympathetic bursts was higher for heart beats occurring during falling than for heart beats occurring during rising blood pressure. For a given change in diastolic blood pressure, sympathetic activity changed more if pressure was falling than if it was rising.6. The findings suggest that the sympathetic outflow is modulated by arterial baroreflex mechanisms and that transient variations in the strength of the activity are, to a large extent, determined by diastolic blood pressure fluctuations. The intimate correlation with ;dynamic' variations in blood pressure and the absence of correlation to the ;static' blood pressure level suggests that the sympathetic outflow to skeletal muscles is of importance for buffering acute blood pressure changes but has little influence on the long term blood pressure level. The difference in reflex sensitivity between falling and rising pressure indicates that acute blood pressure decreases may be buffered more efficiently than acute blood pressure increases.7. In twenty-seven subjects baroreflex latency was calculated from the QRS-complexes in the e.c.g. to the appropriate systolic inhibition in the sympathetic activity. When recording in the peroneal nerve, the latency ranged between 1.16 and 1.49 sec and there was a positive correlation with the height of the subjects. It is suggested that such latency measurements may be used clinically to evaluate conduction in sympathetic fibres.


The renin-angiotensin system and sodium appetite. 1. Bilateral nephrectomy or bilateral ureteric ligation greatly reduced the intake and retention of sodium in sodium-depleted adrenalectomized rats which were experienced at drinking aversive concentrations of saline and which otherwise would have drunk and retained substantial quantities of sodium.2. Pharmacological activation of the renin-angiotensin system with isoprenaline or phentolamine caused increased intake of water but did not stimulate sodium appetite in sodium-replete adrenalectomized rats, and decreased sodium appetite in sodium-depleted adrenalectomized animals.3. Neither I.P. injections of renin nor intravenous infusions of angiotensin II stimulated sodium appetite in normal rats or sodium-replete adrenalectomized rats.4. No differences were found in the saline preference-aversion curves of normal rats not maintained on saline given intracranial injections of angiotensin II or carbachol.5. Preoptic injections of renin, renin substrate or angiotensin II into sodium-replete adrenalectomized rats which were maintained on water and 2.7% saline induced immediate thirst followed by some saline intake. The saline intake was markedly less than the spontaneous saline intake of the same rats when sodium depleted.6. Similar preoptic injections in sodium-depleted adrenalectomized rats caused increased water intake but did not increase the saline intake any further.7. Intracranial injections of carbachol had little effect on saline intake in either sodium-replete or sodium-depleted adrenalectomized rats but caused increased water intake.8. In conclusion, peripheral activation of the renin-angiotensin system stimulates water intake but has no direct effect on sodium appetite. Secondly, central administration of components of the renin-angiotensin system causes thirst and does not inhibit sodium appetite whereas centrally administered carbachol causes thirst and inhibits sodium appetite. Therefore the renin-angiotensin system has only a minor role in sodium appetite.


Pancreatic acinar cells: acetylcholine-evoked electrical uncoupling and its ionic dependency. 1. Isolated segments of mouse or rat pancreas were placed in a Perspex bath through which physiological saline solutions were circulated. Intracellular recordings from surface acini were made by inserting up to three separate micro-electrodes into neighbouring cells within the same acinus. Through one of these electrodes current pulses could be injected. Electrical coupling between the cells could be continuously assessed. The acinus under investigation was stimulated by iontophoresis of ACh from an extracellular micropipette.2. During resting conditions all cells within an acinus were fully electrically coupled. A 5-10 sec pulse of a relatively large iontophoretic ACh ejecting current, causing initially the well characterized surface cell membrane depolarization and resistance reduction, was followed by a marked electrical uncoupling of neighbouring cells. In some cases one cell was clearly being isolated equally from the two other cells impaled, in other cases the cell into which current pulses were injected was becoming more isolated from one of the neighbouring cells than from the other one.3. The ACh-evoked electrical uncoupling was completely reversible and could be repeatedly observed in the same cell.4. The electrical uncoupling in response to short pulses of ACh (5-10 sec) was not affected by even prolonged (up to 50 min) exposure to Ca-free solution containing EGTA.5. ACh-evoked uncoupling (short pulses) was not reduced about 5 min after introduction of Mn (2 mM), Ni or Co (5 mM). Mn thereafter gradually reduced and finally (after about half an hour) abolished the ACh-evoked uncoupling. Ni and Co gradually enhanced the uncoupling response. The blocking effect of Mn on the ACh-evoked uncoupling occurred much faster in the absence of superfusion fluid Ca.6. During a period of sustained ACh stimulation sustained electrical uncoupling was observed. If Ni or Co (5 mM) was introduced during such a stimulatory period the cells recoupled. This effect of Ni and Co was immediate and fully reversible.7. The uncoupling responses to short pulses of ACh was not reduced immediately after replacing superfusion fluid Na by Tris at a time when the surface cell membrane depolarization and resistance reduction was already severely reduced. Thereafter a gradual slow reduction of the ACh-evoked uncoupling was observed. This did not occur if Na was replaced by Li.8. It is concluded that the Ca needed to raise [Ca(2+)](i) sufficiently to cause electrical uncoupling comes from the cells in cases of uncoupling evoked by short pulses of ACh, but from the external solution in cases of sustained uncoupling evoked by sustained stimulation of ACh.


Glucose transport by brush-border membrane vesicles after proximal resection or ileo-jejunal transposition in the rat. 1. The functional properties of the ileal mucosa following jejunal resection or interposition in the jejunum were studied with the help of membrane vesicles. 2. Despite the development of functional and morphological features in the mucosa which are more generally associated with the jejunum than with the ileum, examination of brush-border vesicles derived from ileal and jejunal enterocytes from resected or transposed intestines reveals that the functional characteristics of apical membranes isolated from the different regions of the intestine are maintained after these surgical manoeuvres. Vesicles from control ileum develop an 'overshoot' uptake of glucose that is 3-4 times smaller than that of jejunal vesicles, a difference that is still observed in membranes prepared from mucosa of ileal loops following proximal resection or interposition in the jejunum.