bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Sonic Vibration on Isolated Human Iliac Arteries
Authors: Roach Margot R. , Melech Ewa
Published: April 2011

Eighteen isolated human iliac arteries were exposed to vibrations of 25–1500 Hz for 6–30 h. The vibrations were produced in the nondistended arteries via an intracardiac phonocatheter with a reversed crystal connected to a sound generator via two band-pass filters. The frequencies were divided into four groups (25–30 Hz, 125–300 Hz, 400–500 Hz, and 800–1500 Hz). The last group had little effect on the elastic properties of the arteries. However, the other three groups made the arteries more distensible, with the 25–30 Hz group being most effective. The alteration appears dynamically to be in the elastin (initial slope) rather than the collagen (final slope) of the arterial wall. Nonvibrated control arteries did not change over the same time period.
Evidence for the Heterogeneous Distribution of Chloride in the Barnacle Muscle
Authors: Gayton D. C. , Hinke J. A. M.
Published: April 2011

The kinetics of 36Cl− exchange and the outflow of fiber Cl− into a bath solution of low Cl concentration were studied in single striated muscle fibers of the giant barnacle. The results indicate that the intrafiber Cl− can be divided about equally between a rapidly exchanging fraction which is free in the myoplasm and a slowly exchanging fraction which is either bound or compartmentalized. Furthermore, the free myoplasm Cl− fraction appears to be excluded from about 45% of the intrafiber water. These findings are further evidence in favor of a heterogeneous distribution of water and monovalent inorganic ions in the barnacle muscle.
The Metabolic Fate of Pentylenetetrazol in the Rat
Authors: Ko G. K. W. , Hosein E. A.
Published: April 2011

Pentylenetetrazol administered to rats was metabolized to a derivative which was excreted in the urine along with unchanged pentylenetetrazol. Pentylenetetrazol and its metabolite can be separated on paper chromatograms developed in water-saturated isobutanol. The substances, however, are chromatographically inseparable with water as the mobile phase. Distribution of tritium-labelled pentylenetetrazol in the rat after intraperitoneal injection indicated that it was readily taken up by the liver. Perfusion of the isolated rat liver with citrated blood containing tritiated pentylenetetrazol demonstrated that the metabolite was formed in the intact liver. Formation of the metabolite was inhibited by SKF 525A. The metabolite was isolated from the urine of rats treated with pentylenetetrazol on an Amberlite XAD-2 column and elemental analysis showed it to be a sulfur-containing derivative.
The Further Purification of Motilin, a Gastric Motor Activity Stimulating Polypeptide from the Mucosa of the Small Intestine of Hogs
Authors: Brown John C. , Mutt Victor , Dryburgh Jill R.
Published: April 2011

A polypeptide has been isolated from the duodenal mucosa of hogs and has been named motilin. Motilin stimulates motor activity in both antral and fundic gland area pouches of the stomach of dogs. It will stimulate pepsin output, with no change in H+ secretion, from fundic gland area pouches. Motilin differs from the other characterized gastrointestinal polypeptides both chemically and in its physiological actions. In particular, the presence of phenylalanine as N-terminal residue, the absence of histidine, and presence of large amounts of glutamic acid and glutamine distinguish it from cholecystokinin–pancreozymin and secretin.
Fatty Acid Composition of Carcass, Heart, Liver, and Blood Lipids in Young Lambs Fed Diets Containing Vegetable or Animal Fats
Authors: Bouchard R. , Brisson G. J.
Published: April 2011

Thirty-two crossbred twin lambs were weaned at 3 days of age and artificially reared, for a period of 8 weeks, on milk substitutes containing either tallow or corn oil, at the rate of 26.6% on a dry matter basis. Six additional lambs, twins of six of the artificially reared animals, were left with their dams and used as controls. Lambs fed tallow had legs of lamb which contained more fat (P < 0.01) than those fed corn oil; however, lambs fed corn oil had fatter livers (P < 0.01). On the contrary, the fat content of heart tissues was not influenced by the type of fat consumed. Fatty acid composition of lipids extracted from the leg of lamb, heart, and liver, in general, reflected the fatty acid composition of the dietary fat. Constituent fatty acids of plasma lipids were found in proportions which were also influenced by the type of fat consumed.
Molecular Arrangement for Physiological Action of Glutamic Acid and γ-Aminobutyric Acid
Authors: Gelder N. M. van
Published: April 2011

On combination of the amino group of glutamate or γ-aminobutyric acid (GABA) with a receptor site, RN, the steric influence of the α-carboxyl or γ-hydrogen on the adjacent carbon directs that this site in the receptor separate from surrounding protein structures. In this manner a space may be created in the membrane which measures 5.70–6.30 Å in the case of glutamate and 3.70–4.50 Å for GABA. These values are in good agreement with the diameter of hydrated sodium ions (4.80–5.12 Å) and chloride ions (3.32–3.86 Å). A selective increase in the permeability of the membrane towards sodium or chloride causes, respectively, excitation or inhibition in neurons. The pharmacological action of certain ω-amino acids may therefore be associated with a conformational change in the membrane, required to accommodate the space-filling configuration around the carbon, adjacent to nitrogen. In order that the steric influence of a substituent on this carbon exclusively directs the dimensions of the space to be formed, and for several other reasons, the amino acids probably adopt a specific molecular conformation when interacting with the receptor.
Insulinotropic Effect and Possible Mode of Action of a New Potent Sulfonylurea (BS-4231)
Authors: Brisson Guy R. , Malaisse Willy J.
Published: April 2011

BS-4231, a new sulfonylurea, stimulates insulin secretion by incubated pieces of rat pancreatic tissue. The minimal effective dose is between 3 and 30 mμg/ml. The insulinotropic effect of this agent is transient. It is more marked at intermediate (1.0 and 1.5 mg/ml) than either at high glucose concentrations (3.0 mg/ml) or in the absence of glucose. Experimental data obtained with various inhibitors of insulin secretion suggest that (i) epinephrine suppresses the stimulant action of BS-4231, as well as that of glucose; (ii) mannoheptulose modulates the insulinotropic action of BS-4231 indirectly by altering the effect of extracellular glucose; and (iii) diazoxide faiis to exert any effect upon insulin secretion in the presence of BS-4231. On the basis of these results, it is suggested that BS-4231 might accelerate within the beta-cell some step of glucose metabolism, which is rate-limiting when the insulin secretory process is not fully stimulated by extracellular glucose.
A Method for Studying the Uptake of Creatine by a Perfused Hind Limb Preparation
Authors: Barak A. J. , Beckenhauer H. C. , Tuma D. J.
Published: April 2011

This study describes a surgical and perfusion technique for the in situ maintenance of viability of the hind limbs and tail of the rat. This preparation was used to study the uptake of exogenous creatine from blood perfusate utilizing a tracer technique involving creatine-1-14C hydrate. Under these conditions maximum creatine is taken up in the first 30 min period and continually but decreasingly taken up during 2 h. Although creatine was taken up by the perfused muscle no creatinine appeared in the perfusate above the basal level during the period of perfusion.
Excitation and Prolonged Waking Produced by Catecholamines Injected into the Ventricular System of Cats
Authors: Cordeau J. Pierre , Champlain J. de , Jacks B.
Published: April 2011

Adrenaline and noradrenaline introduced into the third ventricle or cisterna magna of cats in total doses ranging from 50 μg to 3 mg produce wakefulness and excitation. The larger doses produced prolonged arousal (a minimum of 3 h, which was the longest time of observation), accompanied by excitation in the form of restlessness and an apparent compulsive need to be in continuous motion. With lower doses the initial excitation was less marked but could last from 20 to 30 min. This was at times followed by a mild form of sedation which, however, could not in any way be identified as sleep.
Conduction Delay from Purkinje Fiber to Ventricular Muscle Studied with Extracellular Microelectrodes
Authors: Kamiyama Akimitsu , Inoue Fumitake
Published: April 2011

The relationship between electrical activity recorded intracellularly and extracellularly was studied in canine right ventricle. When the tip of a microelectrode was placed against a Purkinje fiber the electrical activity obtained had two components. The first component was a sharp diphasic wave which was defined as an action current while the second component was a rounded and flat diphasic wave which was defined as a field potential. Transmembrane action potentials recorded at the same site indicated that the first component was an active membrane current of the Purkinje fiber while the second component was identified as the field effect potential generated by ventricular fibers lying directly under the layer of Purkinje fibers. In areas where the Purkinje fibers were absent only the second component was present. The time delay of approximately 5 ms between the two components represents the conduction delay of the impulse from the Purkinje fiber to the ventricular fiber.
Report of the Medical Research Council Committee on Human Pituitary Hormones: Radioimmunoassay Kits for Human Follicle Stimulating Hormone and Luteinizing Hormone
Authors: Faiman C. , Shome B.
Published: April 2011

The methodology used in the development of radioimmunoassay kits for human follicle stimulating hormone (FSH) and luteinizing hormone (LH) which are ready for distribution to qualified investigators in Canada is described. Values obtained in measuring the FSH and LH content of serum samples are virtually identical to those obtained with parallel determinations using previously described radioimmunoassay techniques.
Significance of Catecholamine-Induced Ganglionic Blockade and of Reflex Inhibition of Adrenergic Discharge at a Peripheral Locus as Mechanisms Producing Reflex Vasodilatation
Authors: Pollard A. A. , Beck L.
Published: April 2011

An analysis has been made of the various factors which contribute to the vasodilatation observed in the innervated perfused hindlimb when catecholamines are injected intravenously. Bilateral transection of the lumbar sympathetic chains abolishes all dilatation in some animals and greatly reduces dilatations in all animals. When the sympathetic tone lost by chain transection is restored by preganglionic stimulation, the residual hindlimb dilatation still present after chain section is often increased, and a component of dilatation appears de novo in the hindlimb of many animals. This dilatation was blocked by spinal anesthesia. It is concluded that: (1) the peripheral dilatation produced in the hindlimb of the dog by intravenously administered catecholamines is almost entirely reflex in origin; (2) blockade of ganglionic transmission by intravenously injected adrenergic amines does not contribute significantly to the production of reflex dilatation; (3) the residual dilatation remaining after transection of the sympathetic chains is also reflex in origin because it is blocked by spinal anesthesia; (4) the hindlimb vasodilatation which appears de novo during stimulation of the sympathetic chain is also abolished by spinal anesthesia and is apparently due to inhibition of adrenergic discharge at a peripheral locus; (5) in the pentobarbital anesthetized dog, little, if any, of the hindlimb dilatation resulting from the intravenous injection of epinephrine is due to predominant activation of beta receptors.
Immunoreactive Rat Growth Hormone: Physiological Variations in Serum and Urine
Authors: Garay Gabriel L. , Martin Julio M. , Åkerblom Hans K.
Published: April 2011

Immunoreactive rat growth hormone (GH) in serum and urine was measured by a double antibody procedure. Anti-rat growth hormone (anti-RGH) serum was obtained from chickens immunized with three successive 0.25 mg doses of the hormone antigen. Standard amounts of RGH incubated with rat serum were recovered quantitatively. The assay can be used for the determination of GH in rat pituitary extracts as well as for the measurement of hormone secreted from incubated pituitaries. Serum GH concentrations were determined in eight male and 11 female Wistar rats under five different physiological conditions, which were produced in each animal at weekly intervals. GH concentrations in the serum of overnight fasted and ether anesthetized rats were 7.8 ± 2.4 in males and 5.3 ± 0.7 ng/ml in females. Normal feeding or prolonged (48 h) starvation did not significantly alter serum GH in either sex. Exercising for 20 min decreased the serum GH in males to 1.9 ± 0.3 ng/ml and in females to 3.9 ± 0.4 ng/ml. When blood samples were obtained without ether anesthesia GH concentrations were not changed in overnight fasted males (10.2 ± 2.2 ng/ml) and were elevated in females (7.8 ± 0.5 ng/ml). A dialyzable substance, present in the urine of normal rats, interferes with the GH immunoreaction. However, GH was detected in the dialyzed urine of hypersomatotropic rats. These animals had greatly elevated circulating GH due to the pituitary tumor MtT-W15.
Augmentation of Caffeine-Contracture Tension by Twitch-Potentiating Agents in Frog Toe Muscle
Authors: Foulks J. G. , Perry Florence A. , Sanders H. D.
Published: April 2011

Submaximum caffeine-contracture tension in frog toe muscle was enhanced by a number of twitch-potentiating agents (chloroform, pentobarbital, quinidine, nitrate, perchlorate, and impermeant anions) without discernible change in membrane potential. Caffeine-contracture tension also was augmented by diethyl ether. Caffeine-contracture tension was not enhanced by several other twitch-potentiating agents (zinc, tetraethylammonium, and piperidylmethyl androstane). Increased [Mg]0 or [Ca]0 or prior depolarization in high [K]0 did not prevent the potentiation of caffeine-contracture tension by most effective agents. However, enhancement of caffeine-contracture tension by nitrate or perchlorate was largely eliminated by both of these procedures. The monovalent impermeant anions differed from one another in the intensity of their effects on caffeine contractures, and these differences still were evident in the presence of high [K]0. These differences must be attributed to actions exerted at the external surface of the plasma membrane which encloses the fiber and lines its transverse tubules.
Hepatic Origin of Renin Substrate
Authors: Nasjletti Alberto , Masson Georges M. C.
Published: April 2011

By the use of an isolated liver preparation, evidence is presented that the liver is the site of renin substrate (angiotensinogen) synthesis. It is demonstrated that livers from normal rats release substrate, that the release is enhanced by nephrectomy, that the increase after nephrectomy is not accompanied by an increase in labeled proteins in the perfusate and finally that both substrate and total protein synthesis are inhibited by puromycin.
The Effect of Oxotremorine on the "Free" and "Bound" Brain Acetylcholine Concentrations and Motor Activity in Beri-Beri Pigeons
Authors: Igić R. , Stern P.
Published: April 2011

Oxotremorine (0.125 mg/kg i.v.) did not produce a significant change in the "free" and "bound" brain acetylcholine in beri-beri pigeons, while in normal pigeons a significant increase was obtained. Oxotremorine caused tremor in normal pigeons. In beri-beri pigeons oxotremorine did not induce tremor but the compound potentiated beri-beri symptoms (opisthotonus and convulsions).
Neurophysiological Studies of Harmaline-Induced Tremor in the Cat
Authors: Lamarre Yves , Mercier Lise-Andrée
Published: April 2011

Harmaline induces in the cat a generalized tremor, synchronous in all muscles, at a frequency of 8–12/s. This tremor has a central origin since motoneuronal rhythmic firing persists after paralysis or deafferentation. Intracellular recordings of lumbar motoneurons reveal spontaneous rhythmic EPSPs under harmaline; this rhythmic activity is not reset by antidromic stimulation. The cerebellum and the lower brain stem reticular formation appear to be primarily involved in the elaboration of supraspinal tremorogenic impulses, which are transmitted to segmental level by crossed and uncrossed reticulospinal fibers coursing on either side in the ventral half of the spinal cord.
Effect of Age, Sex, and Egg Laying on the Total Erythrocyte Volume (51CrO4 Label) and the Plasma Volume (125I-Serum Albumin Label) of Japanese Quail
Authors: Nirmalan G. P. , Robinson G. A.
Published: April 2011

In a study carried out to assess the effect of age, sex, and egg laying on the true Mood volume in Japanese quail by the simultaneous determination of the 51Cr erythrocyte volume and the 125I plasma volume, the mean values in milliliters per kilogram body weight for true blood volume, plasma volume, and erythrocyte volume in young unsexed quail, adult males, adult nonlaying hens, and laying quail, respectively, were 83.2, 59.1, 24.1; 74.2, 47.3, 26.9; 67.6, 42.9, 24.7; and 71.2, 47.3, and 23.8. Young birds had higher plasma volume and true blood volume and lower whole body hematocrit and Fcells ratio than the adults. The erythrocyte volume of young quail was not significantly different from that of the nonlaying hens but was less than that of adult males. Adult males had higher plasma volume, erythrocyte volume, and true blood volume than nonlaying hens. A comparison between the layers and nonlayers showed that the layers had a higher plasma volume and Fcells ratio and a lower whole body hematocrit than the adult nonlayers.
The Effect of Freezing and Thawing During Storage on the Retinyl Ester: Retinol Ratio in Rat Liver
Authors: Yeung D. L. , Veen-Baigent M. J.
Published: April 2011

The effect on rat liver vitamin A of repeated freezing and thawing and of continuous storage at −15 °C over a 7-week period was studied. Conversion of retinyl ester (RE) to retinol (ROH) began within 1 week in minced liver tissue held under either condition of storage. With intermittent freezing and thawing, the level of ROH reached a peak after 3 weeks of storage, after which time an apparent reesterification of the accumulated ROH to RE took place. In samples that were stored at −15 °C without interruption, the rise in ROH was even more pronounced. Reesterification was also noted in these samples only if they were allowed to thaw for 5 h before assaying for vitamin A.No artefact, analogous with that reported in stored plasma, and which reacts with trifluoroacetic acid to produce spuriously high vitamin A levels, appeared in stored liver tissue.
Changes in Function of the Neuromuscular Junction Occurring in Tick Paralysis
Authors: McLennan H. , Oikawa I.
Published: April 2011

As part of a continuing study on changes in the neuromuscular system produced by the bite of the Rocky Mountain wood tick, it has been shown that the frequency of appearance of miniature end-plate potentials at paralyzed junctions was normal although their mean amplitude was larger, but the increase in their frequency which follows depolarization of the endings by potassium ions was much reduced. In magnesium-poisoned muscles the mean quantal content of end-plate potentials which could be evoked was normal. The changes observed could indicate a defect in the mobilization and/or release of acetylcholine at the terminals, but might conceivably be secondary to the previously demonstrated deficit of conduction in motor axons.
Fatigue and Recovery in Isolated Frog Sartorius Muscles: The Effects of Bicarbonate Concentration and Associated Potassium Loss
Authors: Mainwood G. W. , Lucier G. E.
Published: April 2011

The time course of recovery in isolated frog sartorius muscles was followed by measuring isometric twitch tension after a standard stimulation procedure (400 impulses at 2/s). After stimulation, isometric twitch tension falls to 10–30% of its normal value. Recovery follows three phases: (1) a rapid tension increase within the first 5 min after the end of stimulation which is probably related to the loss of accumulated extracellular potassium; (2) a plateau phase lasting 10–20 min in which a further depression of tension often occurs; (3) a phase of slow tension increase for 30–60 min. In the presence of Ringers solution containing a high bicarbonate concentration (25 mequiv/l), tension recovers to 80–90% of 'rested state' tension in 60 min. In low bicarbonate concentrations (1 mequiv/l) recovery is only 30–40%. Low bicarbonate is associated with a high net potassium efflux during recovery. At a given bicarbonate level small muscles (<100 mg) recover better and lose less potassium per unit weight than larger muscles.
The Metabolic Changes in Frog Sartorius Muscles During Recovery from Fatigue at Different External Bicarbonate Concentrations
Authors: Mainwood G. W. , Worsley-Brown Pauline , Paterson R. A.
Published: April 2011

Superfused sartorius muscles were stimulated to fatigue in either high (25 mequiv/l) or low (1 mequiv/l) bicarbonate solution. The fatigued muscles in both groups showed a loss of about 16 μmol/g wet weight of creatine phosphate (CP) and an increase in lactate of about 20 μmol/g. The small decrease in the mean ATP levels in both groups was not statistically significant. During recovery the rate of loss of lactate from the low bicarbonate group was much slower than from the high bicarbonate group. The initial rate of lactate loss by diffusion was more than twice as fast in the high bicarbonate group. Marked differences were also found in the glucose 6-phosphate level, which was higher, and the CP/creatine ratio which was lower in the low bicarbonate group. The differences between the isometric tension recovery curves and the curious shape of the tension recovery which showed a secondary dip about 15 min after the end of fatigue are interpreted in the light of the measured metabolic changes. It is postulated that intracellular hydrogen ion balance is a critical factor in the recovery process and that external bicarbonate modulates intracellular hydrogen ion balance and at the same time limits the efflux of lactate from the muscle.
Histochemical Identification of Three Types of Intrafusal Muscle Fibers in the Cat and Monkey Based on the Myosin ATPase Reaction
Authors: Ovalle W. K. , Smith R. S.
Published: April 2011

Serial frozen section of muscle spindles in the lumbrical muscles of the cat and the monkey were tested with a recently described modification of the myosin ATPase reaction (Guth and Samaha 1970. Exp. Neurol 28, 365). This reaction is able to detect acid-stable, alkaline-labile myosin ATPase and acid-labile, alkaline-stable myosin ATPase. The reactions were carried out by preincubation of the sections at pH 10.4 or 4.35 with incubation in a substrate at pH 9.4. In both the cat and the monkey three types of intrafusal muscle fibers could be detected on the basis of their reaction for myosin ATPase. Nuclear bag fibers could be divided into two types: those containing the acid-stable form of myosin ATPase only, and those containing ATPase detectable under both acid and alkaline conditions. Nuclear chain fibers contained the alkaline-stable form of ATPase only.
Pressor Effect of Beta Blocking Agents in Rats
Authors: Regoli D. , Regoli U. , Gysling E.
Published: April 2011

In rats anesthetized with urethane, intravenous injection of oxprenolol, propranolol, and d-propranolol increases arterial pressure, while practolol is ineffective. These changes of arterial pressure occur in rats previously treated with phentolamine or phenoxybenzamine, indicating that the pharmacological block of alpha receptors does not prevent vasoconstriction by oxprenolol and propranolol. On the contrary, beta receptor blocking agents have little effect on the arterial pressure of rats treated with a ganglion blocker (pentolinium).The pressor action of adrenaline and angiotensin is significantly depressed by alpha blockers, but small doses of oxprenolol restore completely the action of angiotensin and, in part, that of adrenaline. Adrenaline produces a biphasic effect on the blood pressure of anesthetized rats. Both phases of the effect are eliminated by alpha blockers while ganglion blocker abolishes the hypotensive phase only. Administration of small doses of oxprenolol and propranolol (1–10 μg/kg) in untreated rats or in animals treated with alpha blockers increases significantly the blood pressure, but does not modify the biphasic effect of adrenaline.The results indicate that the pressor effect of small doses of beta blocker may not be entirely related to the elimination of the beta inhibitory effect of exogenous adrenaline on the vascular system. No changes of blood pressure occur when beta blockers are administered to animals treated with ganglion blockers, suggesting that the vasoconstriction produced by propranolol and oxprenolol is not due to a direct effect on the vascular smooth muscles.
The Pharmacology of Passive Cutaneous Anaphylaxis in the Calf
Authors: Wells P. W. , Eyre P.
Published: April 2011

The effects of mepyramine maleate, sodium meclofenamate, methysergide bimaleate, diethylcarbamazine citrate, and disodium cromoglycate on bovine cutaneous anaphylactic reactions and responses to intradermal injections of histamine, 5-hydroxytryptamine, and bradykinin were studied. Calves sensitized by immunization with horse serum in Freund's complete adjuvant were bled to obtain skin-sensitizing serum which was used in passive cutaneous anaphylaxis (P.C.A.) tests. A latent period of 72 h was allowed between intradermal injections of sera and antigen challenge. Mepyramine maleate (10 mg/kg) selectively inhibited responses to histamine and raised the threshold dose of antibody required to elicit a response. Disodium cromoglycate (DSCG, 10 mg/kg) given intravenously 30 min or immediately prior to challenge had no significant effect either on the responses to drugs or on the passive cutaneous anaphylaxis reaction. Diethylcarbamazine (DECC, 20 mg/kg) administered immediately prior to challenge significantly inhibited the cutaneous anaphylactic response and when DSCG was given simultaneously with DECC, this inhibitory effect was apparently augmented. Methysergide (1 mg/kg) and sodium meclofenamate (2 mg/kg) were ineffective in suppressing P.C.A. It is concluded that histamine and a slow-reacting substance (SRS-A) are involved in the mediation of bovine cutaneous anaphylaxis and that kinins may contribute, while 5-hydroxytryptamine would appear unimportant.
Venous Constriction in Response to Head-Up Tilt in Man
Authors: Boréus Lars O. , Hollenberg Norman K.
Published: April 2011

There has been disagreement about the role of the peripheral venous system in cardiovascular adjustments to postural stress in man. In part this seems to be due to the technical difficulty in determining venous distensibility by plethysmographic techniques in situations where concomitant changes in blood flow occur. We have demonstrated in this study that rapid and consistent increases in forearm venous tone assessed by venous occlusion plethysmography do occur on head-up tilt in man, and that they can be readily masked by the parallel marked decrease in forearm blood flow. It is concluded that the peripheral venous system in man is not designed to function only in states of severe stress but rather plays an important role in moment-to-moment adjustments of cardiovascular activity.
Effect of Hippocampal Stimulation on the Plasma Thyrotropin (THS) and Corticosterone Responses to Acute Cold Exposure in the Rat
Authors: Dupont André , Bastarache Edouard , Endröczi Elemer , Fortier Claude
Published: April 2011

Seven days after the stereotaxic implantation of a bipolar electrode in the gyrus dentatus of the hippocampus of adult male rats, exposure to cold (20 min at −5 °C) increased both plasma TSH and corticosterone concentrations, whereas exposure in association with a minor environmental disturbance (presence of an observer) suppressed the TSH response to cold and enhanced the corticosterone response. Concurrent stimulation of the hippocampus with monophasic square waves of 1.3–1.5 V, 10 c.p.s., and 0.1 ms duration was found to restore the TSH response to cold and to inhibit the secretion of adrenocorticotropin (ACTH) (as reflected by the plasma corticosterone concentration). These findings suggest that the concurrent stimulation of ACTH release and inhibition of TSH secretion induced by nonspecific stress are possibly related to depressed hippocampal activity.
Insulin-Like Effects of Phospholipase C in Diaphragm Muscle
Authors: Merrilees Margaret , Haist R. E.
Published: April 2011

Addition of phospholipase C to the incubation medium increased the relative glycogen content of mouse hemidiaphragms, an effect not altered by insulin antiserum. In the presence of glucose or insulin the relative glycogen content was increased by phospholipase C above those levels for glucose or insulin alone.
Vasoactive Actions of Prostaglandins and Serotonin on Isolated Human Umbilical Arteries and Veins
Authors: Park Myung K. , Rishor Charles , Dyer Donald C.
Published: April 2011

Cumulative responses to prostaglandins E1 (PGE1), E2 (PGE2), F1α(PGF1α), and F2α (PGF2α) were obtained on isolated human umbilical arteries and veins. All four prostaglandins produced contractions. PGF2α was the most active prostaglandin on umbilical arteries, while PGE2 and PGF2α were equiactive and more potent than PGE1 or PGF1α on umbilical veins. 5-Hydroxytryptamine (5-HT) was at least 100 times more potent than the prostaglandins. SC-19220, a prostaglandin antagonist, in a high concentration was found to moderately antagonize the vasoactive effect of PGE2 and to slightly antagonize contractions to 5-HT. Also, propylene glycol, the solvent for SC-19220, was observed to antagonize contractions to both PGE2 and 5-HT, thereby indicating that solvent controls are necessary when evaluating compounds such as SC-19220.
Human Skeletal Muscle Glycogen Synthetase Activities with Exercise and Training
Authors: Taylor A. W. , Thayer R. , Rao S.
Published: April 2011

A 5 month training program increased skeletal muscle glycogen synthetase activities of both the 'I' and 'D' forms in human subjects. The level of activity of the enzyme appears to be directly related to the physical fitness level of the subjects tested.
Effects of Propranolol and Epinephrine Infusion on Glycogenolysis in Dog Skeletal Muscle In Situ
Authors: Chapler C. K.
Published: April 2011

The effect of intravenous administration of propranolol and/or epinephrine on glycogen stores in the dog gastrocnemius-plantaris muscle group was assessed at rest and following 30 min of contractions. In resting muscle, glycogen stores were not altered 60 min following propranolol (0.5 mg/kg) nor did a 10 min infusion of epinephrine (1 μg/kg/min) induce glycogenolysis. Following 30 min of contractions at 5 twitches/s, about 30% of the muscle glycogen stores were depleted. This rate of glycogenolysis was unaffected by prior administration of propranolol, suggesting that the breakdown of glycogen during electrical stimulation of the muscle group is not mediated through activation of beta receptors. When epinephrine was infused during the last 10 min of the contraction period, about 50% of the initial glycogen stores was depleted. This epinephrine-induced glycogenolysis was mediated through activation of beta receptors as it was abolished by pretreatment of the animals with propranolol. These data suggest that the relatively small breakdown of glycogen stores in the gastrocnemius-plantaris during electrical stimulation of the muscle group may reflect the lack of an increase in circulating catecholamines.
Metabolic and Pharmacologic Interaction of Ethanol and Metronidazole in the Rat
Authors: Kalant H. , LeBlanc A. E. , Guttman M. , Khanna J. M.
Published: April 2011

Metronidazole, added in vitro, did not act either as an inhibitor or as a substrate for the alcohol dehydrogenase activity of rat liver homogenates. Concentration curves of ethanol and acetaldehyde in the blood after an oral dose of ethanol were not altered by pretreatment with metronidazole; in contrast, disulfiram caused marked elevation of acetaldehyde levels. When given once only, metronidazole (or possibly a metabolite of it) exerted a mild central depressant effect of its own and produced a dose-dependent increase in the intoxicant effect of ethanol. After repeated administration of metronidazole, synergism with ethanol was not seen. An incidental finding was the production of a volatile material during incubation of solutions containing NAD, which gives an acetone-like peak in gas-liquid chromatograms.
Drug-Induced Porphyrin Biosynthesis. VII. Species, Sex, and Developmental Differences in the Generation of Experimental Porphyria
Authors: Creighton J. M. , Marks G. S.
Published: April 2011

The following drugs have been shown to induce hepatic porphyrin accumulation in 5- to 7-weekold chickens: glutethimide, methsuximide, secobarbital, methyprylon, and mephenytoin, Since these drugs are inactive when administered to mice it is clear that a species difference exists in response to these drugs. Administration of 5β-pregnan-3α, 17α-diol-11, 20-dione to 17-day-old chick embryos results in a large increase in δ-aminolevulinic acid synthase (ALA-synthase) activity accompanied by a very small increase in hepatic porphyrin levels. A drug should therefore be screened for its effects on hepatic ALA-synthase activity as well as porphyrin accumulation prior to administration to porphyric patients. Although it has been reported that ALA-synthase activity cannot be induced by drugs in the livers of newborn rats and rabbits, this enzyme is readily induced by drugs in the livers of newborn chickens.
The Effect of Temperature Changes on Tachyphylaxis to Angiotensin In Vitro
Authors: LeMorvan Patrick , Palaic Djuro
Published: April 2011

The effect of heat on the contractility and binding of 14C-angiotensin to guinea pig aortic strips was studied. It was found that heating strips to 47 °C for 20 min causes an increase in maximal response as well as a shift to the left of the dose–response curve for angiotensin while responses to noradrenaline (NA) remain unchanged. This procedure also increases the onset of tachyphylaxis to 10−5 M angiotensin. Heating (47 °C) for varying periods of time decreases the binding of 14C-angiotensin by about 60%. This effect does not seem to be related to the time of heating. It is postulated that this reduction in binding reflects denaturation of nonspecific binding sites on the cell membrane. Heating (47 °C, 20 min) enhanced the binding of 14C-angiotensin to aortic strips which had been rendered tachyphylactic to 10−5 M angiotensin. It is suggested that this is due to the induction of new binding sites.
Strontium Uptake and the Organic Matrix of the Metaphyseal and Diaphyseal Bone in Rat
Authors: Hong K. C. , Iida K. , Cruess R. L.
Published: April 2011

The 85Sr uptake and the phospholipid, collagen, and mucopolysaccharide content of metaphyseal and diaphyseal rat bone were investigated. 85Sr uptake was higher in the metaphysis, which contains more organic material, than in the diaphysis. Metaphyseal bone contained more phospholipid, proline, hexosamine, and hexuronic acid, but less hydroxyproline, than diaphyseal bone. Lecithin, phosphatidylethanolamine, and sphingomyelin were the principal phosphatides of both regions of bone; metaphyseal bone contained slightly more lecithin but there were no significant differences in the percentages of the other two neutral phosphatides. The ratio of hexosamine to hexuronic acid was 1.1 for the metaphysis and 2.4 for the diaphysis. Intravenous administration of polyuronides led to a significant decrease in the strontium uptake of bone.
The Conversion of Methyl-2-Acetoxyethyl-2′-Chloroethylamine to an Acetylcholine-Like Aziridinium Ion and its Action on the Isolated Guinea Pig Ileum
Authors: Hirst M. , Jackson C. H.
Published: April 2011

Methyl-2-acetoxyethyl-2′-chloroethylamine (acetyicholine-mustard) isomerizes in aqueous solution to form a cyclic ion, N-methyl-N-(2-acetoxyethyl)aziridinium, which structurally resembles acetylcholine. It is a potent stimulant of the guinea pig ileum, being approximately one-sixth as potent as acetylcholine at pH 7.4 and one-third as potent at pH 8.4. The agonist activity is inhibited by atropine, by preincubation with acetylcholinesterase, and pretreatment with thiosulfate ion. Mepyramine does not inhibit the stimulant action.One hour exposures of ileum segments to concentrations of acetylcholine-mustard in excess of those producing maximal responses, followed by a 1 h recovery period, did not produce evidence of postsynaptic receptor alkylation. Post-treatment responses to acetylcholine were slightly depressed, but these reductions were not related to the incubation concentrations of the agonist haloalkylamine. Pilocarpine-induced responses were unaltered by this treatment whereas 5-hydroxytryptamine responses were slightly potentiated and histamine responses were slightly and inconsistently modified.These treatments produced persistent, dose-related increases in muscle tone, an effect consistent with accumulations of spontaneously liberated acetylcholine and possibly caused by inhibition of in situ acetylcholinesterase.Ostensibly, the evidence suggests that the acetylcholine-like aziridinium ion can stimulate, but not inhibit, the muscarinic receptors of the guinea pig ileum.
Metabolism of Nucleic Acids and Protein in the Liver, Brain, and Kidney of Female Rats Subjected to Dietary Restriction During the Period of Gestation as well as the Period of Growth, Gestation, and Lactation
Authors: Srivastava Uma , Vu My-Lien , Bhargava Suraj , Goswami Tapas
Published: April 2011

The metabolism of nucleic acids and protein, and. cellular growth, were studied in various organs of female rats subjected to a diet restriction during the period of gestation as well as the period of growth, gestation, and lactation. In general, both body and organ growth were retarded during this restriction, with certain exceptions. For example, only the liver demonstrated a decrease in organ weight when the diet was restricted during the period of gestation only. The number of cells in the various organs decreased in the experimental groups, whereas the cell size was observed to increase. Furthermore it was found that restrictions during the period of growth, gestation, and lactation increased the accumulation of cellular ribonucleic acid and protein content. The metabolism of ribonucleic acid and protein also seemed to have increased significantly.It was concluded that although dietary restriction caused changes in cellular growth, size, and metabolism of various organs these changes were much less marked when the restriction was imposed only during the period of gestation.
Myocardial Contractility. II. Effect of Changes in Cardiac Function on the Subcellular Distribution of Calcium in the Isolated Perfused Rat Heart
Authors: Tomlinson Charles W. , Dhalla Naranjan S.
Published: April 2011

The effects of changes in heart rate and contractile force due to electrical stimulation, alteration of the temperature of the perfusion medium, and varying degrees of stretch tension on the subcellular distribution of calcium in the isolated perfused rat heart were studied. Increasing the frequency of stimulation from 80 to 320 pulses/min decreased myocardial contractility without appreciable changes in the levels of calcium in the tissue homogenate and heavy microsomal (8000 – 40 000 × g) fraction. On the other hand, mitochondrial (800–8000 × g) calcium content was greater in hearts stimulated at 120 pulses/min than in hearts stimulated at 80 pulses/min; further increase in the frequency of stimulation resulted in a decrease in the level of mitochondrial calcium. Increasing the temperature of the perfusion medium from 25 to 37 °C increased the heart rate and decreased the contractile force without any changes in the levels of calcium in the homogenate or subcellular fractions. Increasing the stretch tension on the hearts from 0 to 5 g increased the developed contractile force and the level of heavy microsomal calcium without changing the heart rate or the levels of calcium in the homogenate and mitochondria. The results do not reveal any cause–effect relationship between changes in heart function and subcellular distribution of calcium.
Evidence that Protein Synthesis can be Increased In Vitro Following Cholinergic Stimulation
Authors: Couture Y. , Mongeau R. , Dunnigan J. , Morisset J.
Published: April 2011

These experiments were performed to evaluate secretory and synthetic responses of rat pancreas using in vitro experimental models. With previously described in vitro models, it was impossible to increase pancreatic protein synthesis over control level during or following stimulated enzyme secretion. An in vitro model is proposed combining four different incubation periods: preincubation, stimulation, stabilization, and incorporation. With this model, a 41% increase in protein synthesis has been observed following cholinergic stimulation. This increase occurred only if the previously increased secretion had returned to basal level during the incorporation period. These data would suggest that secretion and synthesis are two separate controlled mechanisms but any increase in synthesis requires a previously increased secretion.
On the Mechanism of the Nicotine-Induced Contracture of Skeletal Muscle
Authors: Thorpe William R. , Seeman Philip
Published: April 2011

A sarcolemma preparation was isolated from rabbit gastrocnemius muscle, and the effect of nicotine on the passive binding of 45Ca2+ to this preparation was investigated. It was found that 10 mM nicotine displaced Ca2+ from the sarcolemma. Sarcoplasmic reticulum was also isolated, and the effect of nicotine and procaine on the release of actively bound Ca2+ was studied. It was found that 10 mM nicotine released 8.1% of the actively bound Ca2+ from reticulum. Procaine (10 mM) inhibited the nicotine-induced release of Ca2+ from reticulum. It is suggested that nicotine can produce contracture of skeletal muscle by displacing Ca2+ from sarcolemma and by releasing Ca2+ from sarcoplasmic reticulum.
Comparative Metabolism of 75Se-selenite, 75Se-selenate, and 75Se-selenomethionine in Bovine Erythrocytes
Authors: Jenkins K. J. , Hidiroglou M.
Published: April 2011

75SeO32− was found to be actively metabolized by bovine erythrocytes. Release of 75Se from red cells was inhibited by 20 mM arsenate, 1.3 mM chromate, 0.5 mM iodoacetamide, 1.0 mM p-chloromercuribenzoate, or high levels of selenite while 20 mM fluoride or 1.0 mM azide had no effect. None of these metabolic inhibitors affected red cell transport of 75SeO42− or 75Se-selenomethionine, which apparently occurred by diffusion. Dialysis of erythrocytes caused an increased uptake of 75SeO32− due to an impairment of 75Se efflux. This effect was prevented by dialysis against 14 mM glucose but not by the presence of 10 mM inosine and 1 mM adenine, the latter added to maintain ATP levels. A hypothesis is proposed to account for the experimental data describing erythrocyte uptake and metabolism of selenite and the likely selenocompound extruded from the cells.
Relation Between Hydrogen Ion Secretion and Oxygen Consumption by Ex Vivo Isolated Canine Stomach, Perfused with Homologous Blood
Authors: Kowalewski K. , Kolodej A.
Published: April 2011

The relationship between oxygen consumption and acid secretion was studied in 28 totally isolated ex vivo canine stomachs, perfused extracorporeally with homologous blood. Two hundred six 30-min samples of gastric juice and blood were collected for biochemical analysis. Paired values of HCl (microequivalents per minute) and O2 consumption (micromoles per minute) were then analyzed by the method of least squares, using a computer. Linear correlation was calculated between these two values. The correlation coefficient was 0.9518 and the slope of the line was 0.512. The ratio of hydrogen ions produced to oxygen molecules consumed was 1.18 ± 0.53. The range of titratable H+ found in this study was from 0 to 833 μequiv/min and the range of O2 consumed was from 18 to 442 μmol/min.
Estrogenic and Anti-estrogenic Effects of DDT Administered in the Diet to Immature Female Rats
Authors: Clement John G. , Okey Allan B.
Published: April 2011

Orally administered o,p′-DDT has estrogenic effects on the uterus of immature rats; stimulation of uterine growth is significant, however, only at doses at or above 1000 p.p.m. o,p′-DDT in the diet. At lower doses (100 p.p.m.) both o,p′-DDT and p,p′-DDT reduce the estrogenic response to injected estradiol-17β, probably by stimulating hepatic degradation of the steroid.
Physiological Disposition of Some Semisynthetic Penicillins
Authors: Rollo Ian M.
Published: April 2011

Two phenoxy penicillins and one phenylthio penicillin were selected for a study of physiological disposition. Phenylthiodiphenyl penicillin was, however, rejected because it underwent complete biotransformation. The resultant substance retained antibacterial activity but lost its resistance to the enzyme β-lactamase.The rate of absorption of phenoxymethyl and phenoxybenzyl penicillins from rat small intestine was at variance with the properties of the substances and the concept of passive, nonionic diffusion. A more detailed study excluded the possibility that some form of specialized transport was involved. The data are consistent with a delay in absorption caused by an interaction between penicillin and some component of intestinal epithelium. Absorption may be further hindered by the formation of penicillin micelles. The relatively polar nature of such micelles would tend to reduce the ability of the parent substance to penetrate lipid-like membranes.Maintenance of high concentrations in the blood is favored by a numerically large partition coefficient, and the associated high degree of binding to albumin and decrease in acidity. It appears that differences in both biliary and renal tubular secretion also play an important part.
Excretion of Sulfinpyrazone in the Rat
Authors: Aldridge A. , Johnson G. E.
Published: April 2011

Male Wistar rats were injected intraperitoneally with 40 mg/kg of 14C-sulfinpyrazone. The drug was rapidly absorbed and its half-life in the blood was 16.2 h. Most of the radioactivity was excreted in the bile. Sixty-eight percent of the dose appeared in the feces and 18% in the urine in the first 72 h. A considerable portion of the radioactivity excreted in bile was reabsorbed in the intestinal tract. One metabolite, p-hydroxysulfinpyrazone, was found in urine, bile, and feces. Previous results have shown sulfinpyrazone to be a uricosuric in man. It is excreted quickly, both as the parent drug and its hydroxy metabolite, in human urine. The failure of the rat to excrete a high percentage of the drug in the urine may be related to its lack of uricosuric properties in this species.