bluuebunny/crossref_metadata_2025 huggingface dataset:
Duration of Action of Two "Long-Acting" Adrenocorticotropin Preparations in the Rat
Authors: Kraicer J. , Conrad R. G.
Published: April 2011

The duration of action of two commercially available "long-acting" adrenocorticotropin (ACTH) preparations was assessed after subcutaneous injection into rats. Plasma and adrenal corticosterone levels were measured as indices of ACTH secretion. Duracton, Nordic (ACTH in carboxymethylcellulose), in doses up to 32 I.U. was effective in stimulating adrenal cortical secretion for less than 12 h. Cortrophin-Zinc, Organon (ACTH – zinc hydroxide), in a dose of 32 I.U., did maintain high plasma and adrenal corticosterone levels for at least 24 h. Therefore the daily subcutaneous administration of Cortrophin-Zinc will maintain high constant circulating levels of exogenously administered ACTH in the rat.
The Effect of Hippocampus on Distraction
Authors: Grillo S. Adeniyi
Published: April 2011

Cortical auditory-evoked responses elicited by clicks were recorded from the acute encephale isole preparation of the cat with cortical electrodes on the primary auditory area. The cortical auditory response consisted of an initial surface-positive deflection which was followed by a slower negative deflection (the secondary wave). This negative deflection was followed by a slower surface-positive deflection. The effect of distraction on the amplitude of the secondary wave was observed. In general, distraction brought about a reduction in the amplitude of the secondary wave. However, stimulation of the dorsal hippocampus during the period of distraction counteracted the effect of distraction on the amplitude of the secondary wave. The results are discussed in relation to the possible role of the hippocampus in the integration of sensory information by the brain.
Effect of Pentagastrin on the Utilization of 3H-Histidine for Histamine Formation by the Stomach of the Rat
Authors: Kowalewski K. , Koheil A. , Russell J. C.
Published: April 2011

Total free histamine (TFH) content and isotopically labelled newly formed histamine (NFH) were determined in gastric and hepatic tissues and in the gastric juice of male rats. Rats were infused intravenously for 24 h at a steady rate with saline or saline containing pentagastrin (gastrin-like C-pentapeptide). 3H-L-histidine, the precursor of histamine, was included in this 24 h infusion. At the end of a 24 h stimulation period, a comparative study of pentagastrin-treated rats and saline-infused controls was performed. Both TFH and labelled NFH were elevated in gastric tissue of pentagastrin-treated animals, as compared with controls. This was considered due to sustained and lasting stimulation of the synthesis of histamine. As expected, pentagastrin infusion stimulated the output of gastric juice and H+. No attempt was made to correlate the action of pentagastrin on histamine formation with post-pentagastrin gastric hyperacidity.
Decreased Half-Life of Some Mitochondrial Proteins in Skeletal Muscle and Brown Adipose Tissue of Cold-Acclimated Rats
Authors: Bukowiecki L. , Himms-Hagen Jean
Published: April 2011

Evidence is presented for a decreased half-life of certain mitochondrial proteins in skeletal muscle and brown adipose tissue of cold-acclimated rats living in the cold; nonshivering thermo-genesis is known to occur in both these tissues. No such decrease occurs in liver or kidney, tissues in which nonshivering thermogenesis does not occur. It is concluded that acclimation to cold causes a change in the rate of synthesis and/or in the amount of certain mitochondrial proteins and that this change may be associated with the development of the capacity for nonshivering thermogenesis.
Effect of Riboflavin Deficiency on the Metabolism of Oxypurines in Chicks
Authors: Chou S. T.
Published: April 2011

Day-old broiler chicks of both sexes were used in three experiments to determine the effect of riboflavin deficiency on oxypurine metabolism catalyzed by xanthine dehydrogenase, a riboflavin-containing enzyme. Chicks fed a riboflavin-deficient diet (1.38 mg/kg) for 3 weeks exhibited depressed growth and a high incidence of curled-toe paralysis (higher than 80%) as compared to control chicks (15.1 mg riboflavin per kilogram diet; no incidence of curled-toe paralysis). In addition, the precursors of uric acid, hypoxanthine and/or xanthine, accumulated in the liver and kidney of deficient chicks showing curled-toe paralysis. These observations show that dietary riboflavin being incorporated into xanthine dehydrogenase is essential for oxypurine metabolism. Moreover in the chick, the liver and the kidney may be important sites of uric acid synthesis. The low uric acid concentration in the plasma of the deficient chicks appeared to be indicative of a disturbance in uric acid synthesis in the liver and kidney.
A Comparative Study of Fibrinolytic Activity in Human, Rat, Rabbit, and Dog Biood
Authors: Hedlin A. M. , Monkhouse F. C. , Milojevic S. M.
Published: April 2011

Fibrinolytic activity in the blood of commonly used laboratory animals: rats, rabbits, and dogs, was compared to that of the human. It was found that the animal blood required activation with high concentrations of urokinase or streptokinase before dilute whole blood fibrinolytic activity could be detected; in contrast, the human samples lysed spontaneously. The failure to detect spontaneous fibrinolysis in the animal blood samples was shown to be due to a high level of antifibrinolytic activity. As demonstrated by this study, the rat, rabbit, and dog are not acceptable as substitutes for the human in fibrinolytic studies.
Pharmacological Studies on Dorsal Root Responses Produced by Ventral Root Stimulation in the Cat
Authors: Esplin Don W. , Čapek R. , Esplin Barbara A.
Published: April 2011

The propagated responses in afferent fibers evoked by ventral root stimulation were studied in unanesthetized spinal cats. Physostigmine increased the amplitude of multi-unit responses and decreased the number of failures of single-unit responses during repetitive stimulation. Dihydro-β-erythroidine had opposite effects. Atropine did not affect the responses. The results suggest that the responses involve a cholinergic junction and are not due to ephaptic transmission.
Late Discharges in Dog's Sympathetic Ganglia
Authors: Chen S. S.
Published: April 2011

In the dog a preganglionic stimulation at a high stimulus frequency for 10–15 s elicited a two-wave response, early and late responses in the perfused ear (vasoconstriction), as well as early and late contractions in the nictitating membrane. Both the late contraction and the late response could be aborted by cooling the superior cervical ganglion, and restored by rewarming the ganglion. Both were resistant to atropine and hexamethonium combined. Their magnitude depended upon the duration of stimulation and upon the stimulus frequency used. Their time courses were similar both before and after hexamethonium or chilling. Therefore, it is concluded that they are manifestations of late discharges in the superior cervical ganglion, which are independent of both muscarinic and nicotinic receptors in the ganglion. A similar but less prominent phenomenon was demonstrated in the lumbosacral sympathetic ganglion of the dog by studying the responses of the retractor penis muscle and the perfused hind limb to preganglionic stimulation.
Uridine-3H Uptake by Human Oocytes
Authors: Ghosal S. K. , Beauregard L. J. , LaMarche P. H. , DeLuca F. G. , Parmar C. P.
Published: April 2011

Small pieces of ovarian biopsy from an 8-week-old human female were incubated in medium containing uridine-3H (UR-3H) for 50 min. The radioautographs of histological sections demonstrated the incorporation of uridine-3H by oocytes. Therefore, the oocyte nucleus appears to be metabolically active in RNA synthesis during the diplotene (dictyotene) stage.
Cyano Compounds and Goitrin in Rapeseed Meal
Authors: Lo M. T. , Hill D. C.
Published: April 2011

Raw rapeseed meals of Brassica campestris and cultivar Bronowski were analyzed for cyano compounds and goitrin following autolysis at 37 °C. Urine excreted from 4 to 36 h by rats dosed with the raw or heated meals (dry heat for 15 min at 110 °C) was also examined for these compounds. Unsaturated nitrile level in raw B. campestris meal was about 20 times, and episulfide A and B and goitrin about 10 times that in raw Bronowski meal. Excretion of unsaturated nitrile and goitrin was consistently higher in the urine of rats dosed with heated meals than those dosed with raw meals. Goitrin was excreted more rapidly in the urine than was unsaturated nitrile.
Evaluation of β-Adrenerglc Blocking Agents in Presence of Adrenergic Tone
Authors: Elharrar Victor , Nadeau Reginald A.
Published: April 2011

The importance of the level of adrenergic tone in the determination of the dose–response curve to noradrenaline (NA) and in the evaluation of β-adrenergic blocking agents was studied in open-chest sodium pentobarbital anesthetized dogs by injecting drugs directly into the sinus node artery. Changes in the level of adrenergic tone by stimulating the right stellate ganglion resulted in variation of the observed chronotropic response to NA and of its ED50. The chronotropic responses were corrected by taking into account the underlying adrenergic tone. The negative chronotropic effect of dl-propranolol (1 and 10 μg) appeared to be related to its β-blocking properties and not to its quinidine-like effects as shown by the lack of effect of d-propranolol injected at the same doses. The magnitude of the negative chronotropic effects of 10 μg of propranolol and 100 μg of practolol, oxprenolol, and sotalol was shown to be related to the initial heart rate and consequently to the level of adrenergic tone. The comparison of these four β-blocking agents was carried out on corrected dose-response curves to NA. Their relative potencies were found to be: propranolol > oxprenolol > practolol > sotalol, corresponding to ratios of 1, [Formula: see text], [Formula: see text], and [Formula: see text]
Effect of Nasopharyngeal Temperature Change on Preoptic and Anterior Hypothalamic Thermosensitive Units
Authors: Mitra J. , Gloor P. , Jell R.
Published: April 2011

Multiunit action potentials were recorded from neurons in the preoptic and anterior hypothalamic area (preoptic region) of the cat. A new method to change brain temperature in the cat was used. It consisted of perfusing the nasal cavity with warm and cold water through tubes inserted into the nostrils. The principle of this method was based on the knowledge that the brain temperature of the cat is dependent upon that of the venous blood in the pterygoid plexus through which the external carotid rete supplying the brain in this species has to pass.Evidence for temperature-sensitive units in the preoptic region was found under these conditions. The response characteristics of the units observed were similar to those obtained in thermode experiments used by other investigators. A regular increase in firing rate with increasing temperature was found in 16.6% of the temperature-sensitive nerve cell population in the preoptic region, A regular increase of firing rate with decrease in brain temperature was observed in 4.7% of the unit records within this population. An additional 34.2% of unit records with evidence of thermosensitivity showed more irregular response curves. Some of these cells seemed to respond only beyond some thermal threshold value. Upon exploration of the lateral geniculate body (14 unit records) two instances of thermosensitivity with increased firing rate with warming were found. Of six unit records taken in the cerebellar cortex, none showed evidence of thermosensitivity.
APL Computer Program for the Analytical and Numerical Integration of Hormonal Disappearance Data
Authors: Normand Maurice
Published: April 2011

The biomedical applications of a new programming language characterized by simplicity and economy of symbols and coupled with access to remote terminals are illustrated by the description and analysis of a program pertaining to the lengthy computations involved in certain aspects of hormonal kinetics and their statistical correlates.
Influence of Citric Acid Administration upon Renal Ammoniagenesis in the Acidotic Dog and Rat
Authors: Welbourne Tomas C.
Published: April 2011

Citric acid reduced ammoniagenesis both in vitro and in vivo by the acidotic dog kidney. In the dog, renal cortical levels of citric acid, α-ketoglutaric acid (α-KG), glutamate, and glutamine were lower in the acidotic than nonacidotic state. Citric acid administration elevated tissue citric acid level 10-fold above the acidotic level, but levels of α-KG, glutamate, and glutamine remained unchanged. In kidney slices taken from acidotic dogs, citric acid levels were greatly elevated reducing ammonia production but failing to increase tissue glutamate. In the acidotic rat kidney, citric acid inhibited ammoniagenesis by incorporating ammonia into glutamate and glutamine. Although citric acid reduces ammoniagenesis in both acidotic rat and dog kidney, the rat kidney produces glutamine and glutamate while the dog kidney does not; consequently the mechanism by which citric acid influences ammoniagenesis appears to differ in the species.
Metabolic Studies on the Mechanisms of Increased Susceptibility of Weanling Rats to Parathion
Authors: Gagné Jacques , Brodeur Jules
Published: April 2011

Equitoxic doses of 32P-parathion (1.5 mg/kg in weanlings of both sexes, 2.0 mg/kg in adult females, and 3.1 mg/kg in adult males) were given by the intravenous route to immature and adult rats in order to investigate the respective contribution of biotransformation, distribution, and excretion phenomena to the increased susceptibility of weanling rats to the acute toxic effects of parathion. At various intervals, the animals were sacrified and the amounts of parathion, paraoxon, diethylphosphorothioic acid, and diethylphosphoric acid in the liver, kidneys, tibial muscle, plasma, brain, adipose tissue, and urine were determined. In vitro metabolism of 32P-parathion by liver homogenates was also investigated. The results obtained suggest that weanlings are more susceptible to parathion than adults mainly because of deficient hepatic mechanisms for degradation of parathion and its toxic metabolite, paraoxon. In addition, the brain tissue of weanlings appears to be more sensitive to the toxic effects of paraoxon than the brain of male adults. On the other hand, the passage of parathion and paraoxon across the blood–brain barrier does not seem to be facilitated in weanlings by comparison with adults. Finally, there is no evidence that the renal handling of parathion and its metabolites might influence the acute toxicity of parathion in weanling and adult rats.
Concerning the Problem of Granular Disintegration in Experimentel Cardiomyopathies
Authors: Pilný J. , Faltová E. , Deyl Z.
Published: April 2011

By using polarized light it was possible to demonstrate that in experimental cardiomyopathies after coronary ligature and after isoproterenol (ISO) administration basically an identical microscopic picture of granular disintegration of the sarcoplasm occurs in rat heart. This type of cell damage starts in a single cell within the range of two neighboring sarcomeres, very likely in the Z-line separating these two sarcomeres. Thereafter it spreads to both ends of the cell and the birefringent material is accumulated into two granules which are dislocated stepwise to both ends of the cell. The process passes to neighboring cells firstly via intercalated discs, and later through intercellular space. In the latter case the process may pass from one cell to another in several places simultaneously which is the explanation for the observation of more granules in the secondarily damaged cells. Large necrotic lesions result from the spreading of the process from one cell to another.A hypothesis has been formulated concerning the identical reaction of the cell to both anoxia caused by coronary ligature and ISO administration. The synergism between continuing contraction and autolytical processes results in the final appearance of granular disintegration of the sarcoplasm.
Effects of Norepinephrine in the Presence of Adrenergic Antagonists and Different Ionic Media upon the Mechanical and 86Rubidium Efflux Responses in Vascular Smooth Muscle
Authors: Chen W-M. , Sunahara F. A.
Published: April 2011

The action of norepinephrine (NE) on the isolated guinea pig mesenteric–portal vein was studied in relation to its mechanical and 86rubidium (86Rb) efflux responses using a continuous flow technique. NE (1 × 10−8 to 2 × 10−6 g/ml) produced dose-dependent increases in both contraction and 86Rb efflux. Phentolamine but not propranolol inhibited both responses to NE. In high potassium medium the 86Rb efflux response was more markedly depressed than the mechanical response. In calcium-deficient medium the NE-induced contraction was abolished but the 86Rb efflux response was potentiated and in high calcium medium there was a significant depression of the mechanical response but no significant difference in the 86Rb efflux response. There seems to be an optimal calcium ion concentration at 2.5 mM for the mechanical responses to NE. These experiments suggest that contraction correlates strongly with an increase in membrane permeability, calcium is required for vascular muscle contraction, and contraction can be initiated by a mechanism independent of changes in membrane potential.
Fatty Acid Enhancement of Bidirectional Flux of Sodium Across Canine Gastric Mucosa
Authors: Ventura Ulderico L. , Schlegel Jerry F. , Code Charles F.
Published: April 2011

This study was done to determine whether the passage of short-chain fatty acids across the gastric mucosa enhances the bidirectional flux of sodium. Four healthy, conscious dogs, each with a vagally denervated gastric pouch, were used. All test solutions contained 147.5 mM NaCl and tracer amounts of 24Na and D2O. Sucrose was added to the control test solution at 40 or 75 mM concentrations. Hexanoic or butyric acids were added to acid solutions (pH 3.5) at concentrations of 40 or 75 mM. Neutral solutions were prepared from the acid solutions by additions of NaOH to pH 7.4. A peristaltic pump perfused and recycled the solutions through the pouches. Transmucosal potential difference (P.D.) was monitored continuously. Samples were taken at the start and end of 45-min periods. The concentrations of the fatty acids, their sodium salts, Na+, K+, Cl−, 24Na, and D2O were determined.At pH 3.5, 25–34% of the fatty acids were insorbed and the bidirectional fluxes of Na+ were accelerated. At pH 7.4, the sodium salts of the fatty acids did not penetrate the mucosa and the bidirectional fluxes of Na+ were unaffected. The transmucosal P.D. was reduced during perfusion with the fatty acid solutions but unaltered when their sodium salts were used. The bidirectional flux of water and the net movement of K+ were not affected by the acid or the neutral solutions. The results indicate that the un-ionized, lipid-soluble fatty acids entered the gastric mucosa and acted there as carriers to enhance specifically the bidirectional transport of sodium.
Lack of Spare α-Adrenoceptors in Cat Spleen
Authors: Davidson W. J. , Innes I. R.
Published: April 2011

The smallest dose of phenoxybenzamine which antagonized responses of cat spleen strips to sympathomimetic amines also decreased the maximal response without impairing the capacity of the muscle to contract. It is concluded that the smooth muscle of cat spleen has no appreciable α-adrenoceptor reserve.
Development of an Anticonvulsant Agent Based on its Effect on γ-Aminobutyric Acid Metabolism
Authors: Wood J. D. , Peesker S. J. , Urton J. I. M.
Published: April 2011

The administration of isonicotinic acid hydrazide (2.2 mmol/kg) plus pyridoxine (4.4 mmol/kg) to chicks 14–18 h prior to exposure to hyperbaric oxygen provided excellent protection against the onset of oxygen-induced seizures in the birds.
Effect of Δ9- and Δ8-Tetrahydrocannabinol on the Peripheral Autonomic Nervous System In Vitro
Authors: Gascon A. L. , Pérès M. T.
Published: April 2011

The purpose of this study was to evaluate the effect of Δ9- and Δ8tetrahydrocannabinol (THC) on some isolated muscles. The results observed show that Δ9- and Δ8THC do not have agonistic activity on the vas deferens, the phrenic nerve – diaphragm, and the ileum preparations. On the other hand, both compounds produce a transient potentiation followed by the inhibition of the acetylcholine-induced contraction as well as a potentiation of the musculotropic activity of noradrenaline on the isolated vas deferens. Furthermore, we have observed that Δ8THC reverses the anti-cholinergic action of atropine, conteracts the anti-angiotensin activity of morphine, and finally, abolishes the potentiation of noradrenaline produced by cocaine. On the phrenic nerve – diaphragm preparation Δ9THC does not modify the contraction produced by nerve stimulation but alters the effect of physostigmine, an anti-cholinesterase inhibitor.
Differences Between B. pertussis and Propranolol Induced Histamine Hypersensitivity in Mice
Authors: Martorana P. A. , Richard J. W. , Share N. N.
Published: April 2011

Evidence was sought to support or negate the hypothesis that B. pertussis induces an autonomic imbalance due to a selective β-adrenergic receptor blockade resulting in hypersensitivity to histamine in mice. An increased sensitivity to the lethal effects of histamine was observed in both B. pertussis and propranolol pretreated mice. However, in contrast with B. pertussis, the magnitude of the propranolol-induced hypersensitivity was significantly lower and exhibited a different dose–response relationship. The symptoms and time of mortality after histamine in B. pertussis-pretreated animals were also notably different from those of propranolol or normal saline pretreated animals. Furthermore, the maximal increase in sensitivity to histamine was significantly greater in animals pretreated with both B. pertussis and propranolol than was observed for either substance alone. Finally, whereas atropine did not exhibit any effect upon the B. pertussis-induced hypersensitivity, significant protection from the propranolol-induced hypersensitivity was observed. Thus, the observations do not support the concept that blockade of β-adrenergic receptors is responsible for the B. pertussis-induced hypersensitivity to histamine in mice, and consequently the mechanism(s) involved in the latter phenomenon remains unresolved.
Renal Function in Saline-Loaded Dogs with Minimal Sodium Excretion
Authors: Levy Mortimer , Lockhart Earle A.
Published: April 2011

In this laboratory, dogs acutely saline-loaded to 7–8% body weight and treated with large doses of antidiuretic hormone and deoxycorticosterone acetate will excrete on the average 400–700 μequiv/min of sodium. We have been able to study five dogs, similarly treated, which for no apparent cause showed a trivial natriuretic response following comparable volume expansion. Postexpansion sodium excretion varied from 30 to 150 μequiv/min. Glomerular filtration rate and arterial blood pressure remained constant, but in each case p-aminohippurate clearance rate (CPAH) fell in response to acute saline loading. Renal vasodilatation with acetylcholine and elevation of perfusion pressure with noradrenaline reversed the sodium retention. Fractional reabsorption in the proximal tubule was normal, and the loop of Henle appeared to be the major nephron site responsible for the augmented sodium reabsorption. Constancy of arterial blood pressure, fall in CPAH, and response to altered intrarenal hemodynamics seem to characterize these saline-loaded dogs with minimal sodium excretion as a unique population.
Inactivation of Exogenous and Neural Noradrenaline by Elastic and Muscular Arteries
Authors: Wyse D. George
Published: April 2011

Contractions of vascular smooth muscle were elicited by transmural stimulation or exogenous noradrenaline, and the rate of relaxation following oil immersion was monitored. Responses to transmural stimulation dissipate more rapidly than equivalent contractions evoked by exogenous amine. Current experiments seek an explanation for this observation. The relative rates for inactivation of exogenous noradrenaline are: rat tail artery > rabbit aorta > rat aorta. It is inferred that the rate of termination of action of noradrenaline is related to the vessel's density of adrenergic innervation.
Permeability of Human Erythrocytes to Isonicotinic Acid Hydrazide and its Metabolites
Authors: Russell D. W.
Published: April 2011

Intra- and extracellular concentrations of isonicotinic acid hydrazide equalized rapidly in suspensions of washed human or rabbit erythrocytes incubated with the drug in Tyrode solution at pH 7.4, 37 °C. Thus, contrary to an earlier report, erythrocytes are not impermeable to this compound. Of its known human metabolites, only the hydrazones with pyruvic and α-ketoglutaric acids were excluded from human erythrocytes.
The Effects of Curare in Limulus Central Nervous System
Authors: Lahue R. , Corning W.
Published: April 2011

Exposure of Limulus abdominal ganglia to (+)-tubocurarine before or after cotton-mouth moccasin venom treatment resulted in a decrease of spontaneous activity in individual fibers in dorsal nerve roots and an inhibition of heart rate, but did not decrease responsiveness of the dorsal nerve to tactile stimulation. No effects of curare were obtained in nonsynaptic regions of nerve bundles either with or without venom pretreatment. Combining acetylcholine perfusion with (+)-tubocurarine resulted in a suppression of the stimulating effect of acetylcholine on dorsal nerve activity.
The Effect of Oxidative Metabolic Substrates on the Membrane Transport of Sugars and on the Action of Ouabain in Skeletal Muscle In Vitro
Authors: Bihler I. , Sawh P. C.
Published: April 2011

Factors which modify sugar transport in muscle were studied by measuring the tissue–medium distribution of the nonmetabolized sugar 3-O-methyl-D-glucose in the rat diaphragm in vitro. Pyruvate, lactate, and β-hydroxybutyrate did not influence sugar transport. n-Octanoate usually stimulated sugar transport but under some conditions antagonized its stimulation by insulin; it also appeared to inhibit the Na+ pump. Succinate also antagonized stimulation of sugar transport by insulin. The effects of these two substrates resemble those of long-chain fatty acids. The inhibition of cation transport by 10−5 g/ml ouabain was not influenced by any of the above oxidative substrates or by insulin. In contrast, the effect of ouabain to increase sugar transport was much increased by the presence of insulin, and was also enhanced by the presence of glucose but not the other oxidative substrates, during a prior interval of incubation. In the combined presence of glucose and insulin internal K+ was elevated and internal Na+ decreased to a small but significant extent.
An Intracellular Study of the Actions of Carbon Dioxide on the Spinal Monosynaptic Pathway
Authors: Esplin D. W. , Čapek R. , Esplin Barbara A.
Published: April 2011

The actions of CO2 were studied on 48 lumbosacral motoneurones impaled with microelectrodes in spinal cats. CO2 produced a reversible depolarization in some cells tested and a reversible hyper-polarization in other cells tested. Both increases and decreases in membrane resistance were produced by CO2, and these were significantly correlated with hyperpolarizations and depolarizations of the membrane, respectively. The after-hyperpolarization following an antidromic response was always reduced by CO2, irrespective of the CO2-induced change in membrane potential. The firing threshold of the motoneurone in response to injected depolarizing currents was increased by CO2. Statistical analysis of excitatory postsynaptic potentials produced by activity in a single afferent fiber revealed that the principal depressant action of CO2 on this pathway is to block intraspinal branches of the primary afferent fibers. Neither the transmitter release mechanism nor the sensitivity of the postsynaptic membrane to the released transmitter was significantly affected.
Central Effects of α-Adrenergic Blocking Agents on Thermoregulation Against Venous Blood-Stream Cooling in Unanesthetized Rabbits
Authors: Preston E.
Published: April 2011

The production or conservation of heat in the rabbit may be mediated in part by adrenergic neurones within thermoregulatory regions of the hypothalamus. The effect of intracerebroventricular injections of α-adrenergic receptor blocking drugs was therefore tested in unanesthetized rabbits subjected to body cooling. Cold water was passed through a metal water-jacketed cuff which was chronically implanted to enclose a section of the abdominal vena cava. The cold water cooled the venous blood returning to the heart and produced a gradual reduction in body temperature. Rectal temperature, shivering, heat loss from the ears, and the rate of body heat extraction were measured.Injection of 50 μg phenoxybenzamine or 350 μg phentolamine into a lateral cerebral ventricle during venous-blood cooling increased the rate of fall in body temperature. Shivering was reduced or abolished, but there was no increase in heat loss from the ears which remained vasoconstricted. After the drug injection, the rabbit lost less heat to the cold water flowing through the cooling cuff. When rabbits were not subjected to blood-stream cooling, the same amount of phentolamine or phenoxybenzamine injected into the lateral ventricle caused vasodilatation and increased heat loss from the ears, and a fall in rectal temperature of 0.23–1.66 °C. These effects on shivering and ear heat loss were not observed following intravenous drug injections at the same dosage, or following intraventricular injections of the drug vehicle.It is concluded that in rabbits undergoing blood-stream cooling, the augmented rate of fall of rectal temperature following intraventricular injection of alpha-receptor blocking agents is caused by reduced heat production. This effect may be due to the blockade of adrenergic synapses in the central nervous system pathways mediating shivering. The vasodilatation in the ears and the fall in body temperature produced in rabbits not undergoing venous cooling indicates that central adrenergic synapses may also mediate the control of blood flow to the skin.
Effect of Cocaine on Na Channel in Toad Skin
Authors: Grin Jaime , Bueno Enrique J.
Published: April 2011

The effects of cocaine on Na channel of the isolated toad skin were studied. (1) Cocaine applied to the external side of the skin diminished its potential difference and short circuit current and increased its resistance to inward current. The effects were inversely related to the external sodium concentration. A Michaelis–Menten analysis showed a competitive antagonism between cocaine and sodium. (2) Cocaine applied to the external side prevented the appearance of the repetitive activity induced by an inward current pulse. When the concentrations of cocaine necessary to prevent the appearance of repetitive activity were studied at different calcium concentrations, a calcium–cocaine antagonism was found, which was also demonstrated in voltage clamp experiments.
ATPase Distribution in Dorsal Neck Muscles of the Cat
Authors: Abrahams V. C. , Rangier F.
Published: April 2011

An examination of the histochemical distribution of ATPase has been made in the synergistic dorsal muscles of the cat neck that move the head. On the basis of this distribution, three types of muscle are described: one pair predominately composed of fibers rich in ATPase, one pair predominately composed of fibers poor in ATPase, and a single muscle with characteristics between the others. The dorsal muscles of the neck are therefore interpreted as comprising three functional groups: one pair of fast muscles, one pair of slow muscles, and a single muscle with intermediate properties.
Inhibition and Enhancement of the Noradrenaline Constrictor Response by Methylxanthines
Authors: McNeill John H. , Hook Jerry B. , Davis Ronald S.
Published: April 2011

Theophylline and caffeine either inhibited or potentiated the noradrenaline constrictor response in an isolated perfused mesenteric artery preparation. The type of response observed was dependent on both the concentration of noradrenaline and the concentration of methylxanthine. Theobromine produced only inhibition of the noradrenaline response.
Incorporation of Radioactivity into Phospholipid Fractions of L5178Y Lymphoblasts after Treatment with Hydrolyzed Nitrogen-14C Mustard
Authors: Goldenberg Gerald J. , Naimark Arnold
Published: April 2011

The distribution of radioactivity in the phospholipid fractions of L5178Y lymphoblasts following treatment with choline-14C and hydrolyzed nitrogen-14C mustard (HN2-OH-14C) was investigated. Incorporation of radioactivity into phosphatidyl choline, phosphatidyl serine, phosphatidyl ethanolamine, and neutral lipid was observed following treatment with HN2-OH-14C but radioactivity was found only in phosphatidyl choline with choline-14C serving as precursor. Enzymatic hydrolysis of phosphatidyl choline liberated most of the radioactivity into the aqueous fraction with choline-14C serving as precursor. However, most of the radioactivity remained in the non-aqueous phase after enzymatic or acid hydrolysis of lecithin with HN2-OH-14C acting as precursor and thin layer chromatography of the non-aqueous, acid hydrolysate revealed 25% of the activity in the lecithin fraction, 38% in the 1,2-diglyceride fraction, and 32% in the non-esterified fatty acid fraction, suggesting possible incorporation of drug into fatty acids. The degree of incorporation of HN2-OH into the lipid fraction compared quantitatively with the amount of active nitrogen mustard bound to DNA and RNA.
Effect of Withdrawal from Chronic Ethanol Ingestion on Phenazine Methosulfate Uptake by Brain Mitochondria and Nerve Endings
Authors: French Samuel W. , Palmer Douglas S.
Published: April 2011

The effect of ethanol withdrawal on the uptake of phenazine methosulfate (PMS) by brain synaptosomal and mitochondrial fractions was studied. Prior studies showed that rats made ethanol dependent developed an abnormality in brain mitochondria characterized by an increase in O2 consumption during succinate-supported respiration when PMS was used as an electron acceptor. In the present study it was shown that ethanol withdrawal induced an increase in PMS uptake by brain mitochondrial and synaptosomal fractions during succinate oxidation. PMS uptake was measured directly. Calcium stimulated the succinate-supported PMS uptake in ethanol-withdrawn rats and controls to the same final level indicating that the maximum uptake of PMS was not affected by withdrawal. The results support the hypothesis that the increase in O2 consumption observed in rat brain mitochondria during ethanol withdrawal was due to an increase in transport of PMS.
A Study of the Effect of Ovex on Parathion Toxicity in Rats
Authors: Black W. D. , Wade A. E. , Talbot R. B.
Published: April 2011

Oral administration (100 mg/kg) of the miticide ovex (p-chlorophenyl p-chlorobenzene-sulfonate) caused a decrease in the hexobarbital sleeping time of rats. Administration of this same dosage of ovex resulted in a significant decrease in the toxicity of orally administered parathion (100 mg/kg) to rats.The changes in rats noted in conjunction with the increased resistance to organophosphate toxicity in vivo were an increased liver size, an increased rate of in vitro α-naphthyl acetate hydrolysis by the 9000 × g liver supernatant.The hexane-extractable organophosphate detected in the liver of the ovex-pretreated rats was significantly lower than the hexane extractable organophosphate found in the liver of the control rats.
Diurnal Variations of Plasma Growth Hormone and Brain Monoamines in Adult Male Rats
Authors: Collu R. , Jéquier J. C. , Letarte J. , Leboeuf G. , Ducharme J. R.
Published: April 2011

Brain levels of monoamines (MA) in the adult male rat show a diurnal pattern of secretion with noradrenaline (NA) and serotonin (5-HT) reaching a peak at 1300 and 1800, respectively, and dopamine (DA) showing a bimodal pattern with peaks at 0500 and 1800. Plasma growth hormone (GH) values fluctuate widely during the nycthemeral period. Statistically significant correlations between plasma GH and brain MA levels, confirming the existence of a physiological role of MA in the control of GH secretion, could not be demonstrated in the present study.
Studies Related to the Cholinergic Influence on the Accumulation and Disappearance of Monoamines in Rat Brain
Authors: Bhatnagar Satya P.
Published: April 2011

The influence of atropine, hemicholinium base No. 3 (HC-3), and physostigmine on the changes produced in the cerebral levels of monoamines by pargyline, α-methyl-p-tyrosine (α-MT), and reserpine was investigated in rats. The results disclosed that atropine and HC-3 decreased both the accumulation of dopamine (DA) after monoamine oxidase inhibition with pargyline and its disappearance after tyrosine hydroxylase inhibition with α-MT. Both drugs caused an increase of noradrenaline (NA) disappearance after α-MT but neither affected the accumulation of NA after pargyline. In contrast, physostigmine inhibited the loss of NA and accentuated that of DA. HC-3 markedly inhibited the accumulation of serotonin (5-HT) while other drugs exhibited no significant effect. Choline partly antagonized the action of HC-3 on DA and 5-HT accumulation. The neuroleptic haloperidol increased the α-MT-induced loss of catecholamines. Atropine and HC-3 partially blocked the haloperidol–α-MT effect on DA levels but increased the effect on NA levels. Physostigmine had effects opposite to those of atropine or HC-3 in haloperidol–α-MT-treated rats. Reserpine-induced depletion of catecholamines or their subsequent recovery was not affected by any of the test drugs. Pargyline afforded considerable protection against the in vivo toxicity of HC-3 in mice, while it potentiated the lethal effects of choline and physostigmine.
Studies Concerning the Source of Calcium for Contraction of Rat Myometrium
Authors: Hodgson B. J. , Daniel E. E.
Published: April 2011

Uptake and efflux of 89Sr in pregnant rat myometrium were not different from uptake and efflux of 45Ca although tension studies indicated that Sr2+ does not become sequestered. The effects of Ca+-free solution on uterine responses to acetylcholine (ACh) and K+ suggest that at 37 °C, these agents cause release of calcium from the same pool. Substitution of Na+ by Li+ in the medium caused a contraction which was dependent upon extracellular Ca2+, and which was accompanied by increased 45Ca uptake and increased Ca2+ content. Three inhibitory drugs lanthanum, SKF 525-A, and chlorpromazine inhibited responses of myometrium to ACh and K+, but did not demonstrate selective inhibition of one of these stimulants. Effects of these inhibitory drugs were at least partially due to decreased frequency of action potential discharge. Of these three inhibitory agents only lanthanum inhibited (partially) 45Ca and 89Sr uptake into myometrium.The lanthanum technique for measurement of cellular 45Ca influx failed to demonstrate differences in pools of calcium utilized for ACh and K+ induced contractions. The effects of lanthanum in contractility and 45Ca experiments are discussed.
Effect of Cycloheximide on In Vitro and In Vivo Protein Synthesis by Certain Tissues of Rats and Pigeons with Special Reference to Muscle
Authors: Narayanan Njanoor , Eapen Jacob
Published: April 2011

The effect of cycloheximide in vitro and in vivo on the incorporation of labelled amino acids into protein by muscles, liver, kidneys, and brain of rats and pigeons was studied. In vitro incorporation of amino acids into protein by muscle microsomes, myofibrils, and myofibrillar ribosomes was not affected by cycloheximide. In contrast, administration of the antibiotic into intact animals at a concentration of 1 mg/kg body weight resulted in considerable inhibition of amino acid incorporation into protein by muscles, liver, kidneys, and brain. This inhibition was observed in all the subcellular fractions of these tissues during a period of 10–40 min after the administration of the precursor. Tissue homogenates derived from in vivo cycloheximide-treated animals did not show significant alteration in in vitro amino acid incorporation with the exception of brain, which showed a small but significant enhancement.
The Refractory Period and the Duration of the Plateau of the Active State in Frog Skeletal Muscle
Authors: Clinch N. F. , Tennant V.
Published: April 2011

Isometric contractions of frog sartorii in response to paired stimuli (I ms apart) were compared with isometric twitches following single shocks in order to find the time of the first detectable mechanical response to the second shock (ts). For I > 25 ms at 0°, ts = 0.99 I + 13.3 ms; while for I < 25 ms, ts was found to be independent of I. Electrical recording from the muscle surface showed that for I < 25 ms, the second action potential fell within the relative refractory period of the first. The plateau region of the ts–I plot is consistent with the active state theory, but can also be interpreted as (a) a measurement artifact, or (b) revealing electrical properties of the membrane rather than a property of the contractile mechanism itself.
The Effects of Pretreatment of Mice with Norethindrone on the Metabolism of 14C-imipramine by the Liver Microsomal Drug-Metabolizing Enzymes
Authors: Bellward G. D. , Morgan R. G. , Szombathy V. H.
Published: April 2011

An assay procedure for the metabolism of 14C-imipramine in vitro is described. Using female mouse liver as the enzyme source, the conditions of the assay have been determined for the formation of 2-hydroxyimipramine, desmethylimipramine, and imipramine-N-oxide. Demethylation was linear up to a substrate concentration of 120 μg/3.5 ml, N-oxidation was linear up to a concentration of imipramine of 70 μg/3.5 ml, and hydroxylation up to 20 μg/3.5 ml of reaction mixture. Desmethylimipramine competitively inhibited both hydroxylation and demethylation, whereas imipramine-N-oxide had no effect. Pretreatment of mice with norethindrone decreased hydroxylation, and increased demethylation. Cytochrome P-450 was also increased by this progestin; N-oxidation was not changed. The effects of concurrent administration of norethindrone with known inducers or inhibitors of drug metabolism have been determined. From these experiments, it was concluded that the induction of cytochrome P-450 by norethindrone is not responsible for the increased demethylation of imipramine. Rather, it appeared that competitive inhibition of hydroxylation of imipramine by the norethindrone allowed more of the drug to be demethylated.
The Effect of Replacement of Potassium by Cesium Ions on Neuromuscular Blockade of the Rat Phrenic Nerve – Diaphragm Preparation In Vitro
Authors: Korey Andrew , Hamilton John T.
Published: April 2011

The effect of potassium replacement by cesium in the rat diaphragm preparations has been investigated using conventional intracellular recording techniques; end-plate potentials (EPP's) recorded in modified Krebs' solution with lowered Ca2+ and high Mg2+ were increased until twitching in response to indirect stimulation was restored. This increase in amplitude of the EPP was not acccompanied by any change in the magnitude or frequency of miniature end-plate potentials (MEPP's) suggesting that Cs+ is acting presynaptically to increase evoked release of transmitter. Similar augmentations of EPP's were observed in preparations paralyzed with d-tubocurarine, gallamine, pancuronium, or decamethonium. Parallel studies showed that the mechanical response of the preparations returned towards control values after K+ substitution by Cs+ in diaphragms that were blocked by the above agents but not those blocked by hemicholinium.The results are consistent with the conclusion that the presynaptic action of cesium can overcome directly any effect that the clinically used blocking agents may have on presynaptic sites and that the increased release of transmitter by cesium is sufficient to overcome indirectly the depressant effects of the blocking agents at postsynaptic end-plate receptors.
Effets de l'Amide de l'Acide Lysergique-25 sur la Réaction de Sursaut chez le rat
Authors: Miliaressis T. E. , St-Laurent J.
Published: April 2011

La réactivité et l'habituation à un stimulus sonore répétitif ont été testées à l'épreuve de la réaction de sursaut chez 32 rats ayant été préalablement soumis à une injection de soluté physiologique ou à des doses croissantes de l'amide de l'acide lysergique-25 (LSD-25). Le LSD induit un syndrome d'hyperréactivité représenté par une amplification de la réaction de sursaut et par un ralentissement du processus d'habituation, l'importance de ce phénomène étant une fonction directe de la dose utilisée. Etant donné l'existence d'une hyperréactivé similaire par stimulation des noyaux du Raphé mésencéphalique, ces résultats suggèrent que ces structures nerveuses ainsi que la sérotonine sont impliquées dans le niveau de réactivité chez le Rat.
Effects of Furosemide and Ethacrynic Acid on Cation Transport Across Phospholipid Bilayer Membranes
Authors: Singer M. A.
Published: April 2011

Phosphatidylcholine vesicles acquire a negative surface charge in the presence of furosemide or ethacrynic acid. In addition, these same vesicles also display a higher efflux rate for 22Na and 86Rb when exposed to these two diuretics. The experiments reported in this study indicate that the increased cation permeability is due to the creation of this negative surface charge. Cations will accumulate in the electrical double layer adjacent to the interface, resulting in a larger trans-membrane flux. In addition, ethacrynic acid also facilitates H+ transport in these vesicles, a property not shared by furosemide. Although the explanation for the enhanced H+ permeability is unclear, the experiments indicate that it occurs through a different mechanism than that by which alkali-metal cation movement is increased.
Epileptiform Seizures in Domestic Fowl. IV. The Effects of Anticonvulsant Drugs
Authors: Johnson D. D. , Crichlow E. C. , Crawford R. D.
Published: April 2011

The ability of phenobarbital, diphenylhydantoin, trimethadione, and diazepam to modify epileptiform electroencephalogram (EEG) activity and prevent motor seizures in chickens genetically predisposed to convulsions was observed. These drugs prevented motor seizures and suppressed changes in the EEG normally induced by intermittent photic stimulation without producing an observable effect on the interictal EEG.
Cold Vasodilatation of the Rat Tail
Authors: Hellström B.
Published: April 2011

The tail-skin temperature was measured in nine male albino rats resting at chamber air temperatures between 40 and 16 °C. Spontaneous increases of tail temperature, strongly indicative of cold-induced vasodilatations (CIVD), were evoked by immersing the tail in ice water. The reproducibility of onset time and peak time of the CIVD was best for the first wave of temperature increase. Tail temperatures prior to immersion indicated vasodilatation when the rat rested at chamber temperatures of 28 °C or above, vasoconstriction when the chamber was kept at 24 °C or lower. The number of rats showing CIVD decreased with decreasing ambient temperatures below 32 °C.