bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental hypertension in pregnant sheep
Authors: Holm Louis W. , Katz Yale J. , Parker Harold R. , Chesley Leon C. , Assali Nicholas S.
Published: December 2017

Sheep with spontaneously occurring or experimentally induced toxemia of pregnancy do not develop hypertension despite the presence of a marked renal ischemia. The present study was undertaken in order to investigate whether pregnant sheep, like pregnant dogs and rats, do not exhibit hypertension when subjected to renal artery constriction. Bilateral constriction of the renal arteries was performed on pregnant ewes by a modified Goldblatt-Wakerlin technique, after control blood pressure had been recorded for several days. Blood pressure and BUN were measured throughout pregnancy and following delivery. All the animals which had renal artery constriction developed severe hypertension with retinal changes similar to those of human hypertension. The pregnancy did not affect the course of the hypertension nor did the hypertension alter the course of pregnancy.
Propagation of impulses in the His-Purkinje-ventricle system
Authors: Alanís Jesús , Pilar Guillermo
Published: December 2017

In isolated and perfused hearts of dogs, electrical activities of the A-V node, bundle of His and ventricular fibers were recorded simultaneously. The activity of the Purkinje tissue was also recorded from an exposed false tendon of the right ventricle. When the auricle was stimulated with rates from 1 to 3/sec., the average latency between the activation of the bundle of His and the Purkinje fibers (H-P) was 21 msec. If these structures were stimulated either through the auricle or through the ventricle, a latency was recorded between the activation of the Purkinje tissue and the endocardial ventricular fibers (P-V and V-P). These average latencies were 30 msec. When the ventricle was stimulated with progressively increasing frequencies, the bundle of His could not follow frequencies above 6.5/sec., while the ventricular and Purkinje fibers followed up to 7.8/sec. During fibrillation, the average maximal frequency of the responses of the bundle of His was 6/sec.
Acylphosphatase and adenosinetriphosphatase of hibernating hamsters
Authors: Mokrasch L. C.
Published: December 2017

Acylphosphatase (AcOPase) and adenosinetriphosphatase (ATPase) in brain stem, cerebral cortex, cerebellum, hippocampal region and thalamic-hypothalamic region of the brain and in liver, heart and skeletal muscle of hibernating hamsters were compared with those in the corresponding parts of nonhibernating hamsters. The AcOPase of the brain zones of hibernators is more active than that of nonhibernators when measured at 0°C. Some brain parts show a greater difference than others. The brain parts of both groups are about twice as active in AcOPase as are the body parts and differences between the groups are less apparent when measurements are made at 38°. Differences between the two groups in ATPase are increased when the assays are made at 0° and in the presence of 3-phosphoglyceric acid, the hibernators having the more activity. It is concluded that ATPase is insufficient to maintain homeothermy near 0° and that AcOPase may provide the thermogenesis for both the low temperature homeothermy and for the early part of arousal. The alterations in the enzymes of hibernators appear to be adaptive changes consistent with the postulated role of acylphosphatase.
Metabolism of acetate in scorbutic guinea pigs
Authors: Banerjee Sachchidananda , Ghosh Pulak Kumar
Published: December 2017

The effects of feeding acetate on the glucose tolerance, deposition of liver glycogen; urinary excretion of citric acid, malic acid and ketone bodies; total body lipid, phospholipid and cholesterol; and cholesterol content of different tissues were studied in normal and scorbutic guinea pigs. The effects of prolonged insulin treatment on the urinary excretion of citrate, malate and ketone bodies were also studied in normal and scorbutic guinea pigs fed acetate. It was observed that when normal guinea pigs were fed acetate, total body lipid and liver glycogen increased and there was no change in body cholesterol, tissue cholesterol and glucose tolerance. In scorbutic guinea pigs total body cholesterol and cholesterol contents of blood, small intestine and testes were increased and were further enhanced when the animals were fed acetate. Lowered glucose tolerance, diminished liver glycogen, total body lipid and phospholipid observed in scorbutic guinea pigs did not change after acetate feeding. The increased urinary excretions of ketone bodies, citric acid and malic acid by scorbutic guinea pigs came down to normal levels when they were injected with insulin. The increased cholesterogenesis in scurvy seems to be due to hypoinsulinism.
Effects of hydrocortisone, prolactin and oxytocin on lactational performance of rats
Authors: Talwalker P. K. , Meites J. , Nicoll C. S.
Published: December 2017

The effects on lactational performance of 0.25-, 0.5- or 1.0-mg doses of hydrocortisone acetate, 1.0 mg prolactin (1.0 mg = 20 iu) or 1.0 iu oxytocin given twice daily, were studied in 90 mature female albino rats of the Carworth strain. Litter weight gains were used as a measure of milk secretion. When hydrocortisone acetate, oxytocin or prolactin were injected individually, only hydrocortisone acetate at the 0.5-mg dose level increased milk secretion significantly ( P < .05) and neither prolactin nor oxytocin altered milk yield. When all three hormones were injected in combination, the effects on lactation were the same as with the individual hormones and only the combination containing 0.5 mg hydrocortisone acetate increased milk secretion. These results indicate that adrenal glucocorticoids have the ability to increase milk secretion in the rat and it is believed that this effect is due to its direct action on the mammary gland.
Acute effects of brief ureteral stasis on urinary and renal papillary chloride concentration
Authors: Kessler Richard H.
Published: December 2017

According to the countercurrent hypothesis urine tonicity depends largely on osmotic equilibrium of collecting duct fluid with the hypertonic interstitium of the papilla. One suggested role of ADH is that of regulating water permeability of collecting duct epithelium. In water deprivation ADH would facilitate water movement from collecting duct to the hypertonic papilla. Support for this hypothesis is offered here. These studies use the observation that ureteral clamping curtails glomerular filtration. Hence, the filtered load of NaCl from which papillary stores are derived is reduced. Accordingly, the chloride content of papillary tissues obtained from dog kidneys subsequent to several minutes of ureteral clamping was compared to those from the opposite kidney. In saline-loaded animals stasis uniformly lowered tissue chloride with the production of urine lower in chloride content and hypotonic to that of the contralateral side. These alterations were minimized following urinary stasis in animals loaded with water, mannitol or saline plus ADH.
Transient secretion of phosphate in relation to underlying plasma level in the dog kidney
Authors: Carrasquer Gaspar , Brodsky William A.
Published: December 2017

Transient renal responses to close arterial instantaneous injections of NaH2PO4 and creatinine ( ca. 500 µmoles of each) were studied in dogs under conditions of high urine flow with ‘normal’ (0.5–1 mm/l.), and with high (3–5 mm/l.) levels of serum phosphate. When serum phosphate was at normal levels (no exogenously administered phosphate), the increment of phosphate excretion per unit injected per one circulation of injected substance was equal to or less than that of creatinine. When serum phosphate was elevated (by continuous infusion of NaH2PO4 for 1 hr. preceding injection), the increment of phosphate excretion per unit injected per one circulation exceeded that of creatinine. Such findings suggested the existence of a tubular secretory mechanism for phosphate. Dependency of the postulated mechanism upon cellular reserves and/or plasma concentration of phosphate is discussed.
Effects of caloric intake on clearance of injected lipids in rabbits and rats
Authors: Ammerman C. B. , Iacono J. M. , Wendel Lucille P. , Isaac G. J.
Published: December 2017

Rabbits fasted 3 and 10 days displayed marked increases in serum total fatty acids and total cholesterol, limited increases in lipid phosphorus and a distinct inability to clear intravenously injected triglycerides from the serum. Limited feeding in which rabbits were losing weight over a 10-day period resulted in essentially no change, either in serum lipid components or lipid removal rates. The adverse effects of fasting on serum lipid clearance appeared to be partially overcome by injecting additional glucose at the time of lipid administration, and completely overcome by giving heparin intravenously 15 minutes prior to lipid injection. Rats fasted 4 days showed decreased levels of serum total fatty acids, lipid phosphorus and total cholesterol, but maintained normal rates of serum lipid clearance. Limited-fed rats showed less pronounced decreases in serum total fatty acids, lipid phosphorus and total cholesterol, and also maintained normal serum lipid clearance.
Neurophysiological effect of 3-cm microwave radiation
Authors: McAfee Robert D.
Published: December 2017

Neurophysiological effects from locally applied 3-cm microwave irradiation are demonstrated on decerebrate and anesthetized cats and shown to be the result of thermal stimulation of peripheral sensory nerve fibers. The penetrating characteristic of 3-cm radiation heats these fibers within the skin and subcutaneous tissue to 45° ± 2°C at which temperature a nociceptive response is elicited from the experimental animals. The irradiation is applied to small areas of skin or short sections of nerve trunks rich in sensory fibers and the nociceptive response obtained is quite different from the signs of a hyperthermal state seen during whole-body microwave irradiation.
Effect of acute hemorrhage on carotid occlusion response in the cat
Authors: Bevan J. A. , Prior R. D. , Verity M. A.
Published: December 2017

The relationship between carotid occlusion response and mean arterial pressure, after small successive hemorrhages, was investigated in the cat anesthetized with α-chloralose. Carotid occlusion response decreased as arterial pressure fell to a level of about 130 mm Hg, but below this level, carotid occlusion response increased. This increase was found to be due to carotid chemoreceptor activity, as it disappeared when the animal breathed oxygen immediately prior to and during the occlusion and was absent in animals after carotid chemoreceptor inactivation. This increase was not present in animals anesthetized with sodium pentobarbital. As this increase was also present in the unanesthetized animal, pentobarbital in anesthetic doses must block the effect of carotid chemoreceptor activity, probably by a central action. In 20% of the animals the carotid occlusion response increased after the first few hemorrhages by an amount equal to the fall in arterial pressure. This increase was not due to chemoreceptor activity, but was probably due to a ceiling phenomenon.
Irreversible hemorrhagic shock in dogs: problem of onset of irreversibility
Authors: Hift H. , Strawitz J. G.
Published: December 2017

Various time course studies were conducted in dogs subjected to a modified Wiggers procedure in an effort to ascertain whether the first reinfusion demand (the earliest overt sign of cardiovascular instability) could be associated with any other measurable biological change. The biphasic blood glucose pattern characteristic of irreversible hemorrhagic shock was thus shown generally to reach its hyperglycemic peak shortly before or at the time of first reinfusion, typically preceded by or coinciding with the earliest morphological changes in liver mitochondria (phase contrast, electron micrographs) and followed by progressive lengthening of the prothrombin time. The declining phase in blood glucose concentration was apparently not associated with any critical liver glycogen level or with any unusual rises in blood lactate, etc. The suggestion is therefore made that the sugar is used metabolically because of a liver shutdown induced by some extrahepatic agent(s) and that these events may, in turn, elicit malfunction elsewhere, e.g. the heart.
Pulmonary blood flow, pressure and resistance following tetraethylammonium and aminophylline
Authors: Harasawa M. , Rodbard S.
Published: December 2017

The effects of tetraethylammonium chloride (TEAC) and aminophylline on the pulmonary vascular resistance were studied in thoracotomized dogs. Pulmonary arterial blood flow and pressure, and systemic blood pressure were measured simultaneously. Both drugs showed marked hypotensive effects on the systemic vessels. In every instance pulmonary arterial pressures and blood flows were reduced by TEAC given via the pulmonary artery and increased by aminophylline. However, the calculated pulmonary vascular resistance remained essentially unchanged in all experiments. These data challenge the concept that the pulmonary vessels respond to these drugs by active vasodilatation
Effect of ventricular tachycardia and arteriovenous fistula on catecholamines blood level
Authors: Nakano Jiro , Zekert Horst , Griege Charles W. , Wang Kuang-Mei , Schaefer Helen S. , Wégria René
Published: December 2017

In the anesthetized dog, experimentally induced ventricular tachycardia resulted initially in a very marked decrease in mean arterial blood pressure and cardiac output, then blood pressure and cardiac output rose and stabilized slightly below or markedly below their control levels. Such tachycardia resulted in a rise in the catecholamines blood level. Acute arteriovenous fistula resulting in a definite decrease in mean arterial blood pressure followed by complete or partial recovery of the blood pressure also resulted in an increase in the catecholamines blood level. The mechanisms, origin and role of this increase in catecholamines blood level are discussed.
Fractionation of the motor unit: response to tetanus
Authors: Locke Simeon
Published: December 2017

The effect of a tetanus on the motor unit of the gastrocnemius of the rat has been studied before and after administration of blocking agents. Post-tetanic potentiation of action potential of the single motor unit occurs following depression of response by curare or decamethonium. Increased amplitude of unit potential results from partial resynchronization of subunit potential contributions which had been desynchronized by the differential effect of the blocking agent on subunit latency. Decline of unit potential subsequent to post-tetanic potentiation results from desynchronization of component contributions as had been observed with initial administration of blocking agent. The occurrence of these events in a single motor unit indicates that they take place at the nerve terminal or subterminal portion of the unit.
Effect of Mercuhydrin on sodium transport in proximal tubules of dogs in stop flow
Authors: White H. L. , Rolf D. , Bisno A. L. , Kasser I. S. , Tosteson D. C.
Published: December 2017

When Na22 is infused into a renal artery under stop-flow conditions in a dog in mannitol diuresis, little or no movement of sodium from plasma into tubule lumen occurs distal to the tubule site of production of the sodium trough, whereas the more proximal walls are highly permeable to sodium. Sodium flux across proximal walls is increased by Mercuhydrin. This is interpreted as evidence for increase in passive leak, which is presumed to be partially or wholly responsible for the natriuretic effect.
Distribution of absorbed strontium-85 and calcium-45 as influenced by lactose
Authors: Lengemann F. W. , Comar C. L.
Published: December 2017

Studies on the absorption and subsequent deposition in bone of Sr85 and Ca45 injected into ligated sections of small intestine of the rat showed that: a) more Ca45 than Sr85 was absorbed from the intestine; b) especially during the 1st 4 hr, significantly more of the absorbed Sr85 than Ca45 was deposited in bone; c) injection of lactose, lysine, or glucose into the ileum, along with the alkaline earths, caused the absorbed Ca45 to deposit in the bone at the same rate as the Sr85, and also caused an increased total absorption of both radionuclides; these observations did not hold for the duodenum or jejunum, confirming differences in mechanism among the sections of the small intestine. Tentative explanations are suggested, the most plausible one being that calcium is bound as it is absorbed from the small intestine and that the presence of lactose in the intestine inhibits the production of the bound form.
Functional role of median longitudinal fasciculus in evoked conjugate ocular deviations in cats
Authors: Hyde Jane E. , Slusher Margaret A.
Published: December 2017

Functional deficits of evoked conjugate ocular movements were assessed following acute surgical interruption of the median longitudinal fasciculus (MLF) in cats prepared as encéphale isolés. a) In horizontal deviations, adduction evoked by stimulation of dorsal midbrain, zona incerta and medial reticular substance of medulla was abolished by bilateral section of the MLF at or anterior to the level of the 6th nucleus. Unilateral sections differentially abolished adduction from the three stimulated areas. Abduction from dorsal midbrain stimulation required a higher voltage following section of MLF between or just posterior to the sixth nuclei. b) Conjugate ocular torsion evoked by stimulation of zona incerta was significantly altered by sections of internuclear MLF as well as by coagulating lesions in the vestibular nuclear complex. Results indicate first that no single group of fibers in the MLF serves as ‘the common path’ for ocular adduction in all types of horizontal conjugate movements. Second, the degree of torsion induced by stimulation of the zona incerta is at least partially dependent on vestibulomesencephalic impulses ascending the MLF.
Electrical potentials across isolated small intestine of the rat
Authors: Clarkson T. W. , Cross A. C. , Toole S. R.
Published: December 2017

Electrical potential measurements indicated that the absorption of salt across the small intestine was the result of active transport of Na+, followed passively by an equivalent of Cl–. The potential across the intestine was positive on the serosal side and higher in the jejunum than in the ileum. The Na+ concentration in the bathing media determined the magnitude of the potential; other monovalent ions had no effect.
Effect of removal of lymphatic tissue on immune response in mice
Authors: Swartzendruber D. C. , Bigelow R. R. , Congdon C. C. , Makinodan T.
Published: December 2017

Extensive lymphatic tissue removal in mice prolonged skin homograft survival as long as 32 days in one animal, but the longest median rejection time for a given experiment was 17 days. The longest homograft survival in sham-operated controls was 14 days; median rejection time was 10 days. A median rejection time of 18 days was seen in a few mice given 400 r after the extensive lymphatic tissue removal. When second set homograft response was studied there was no significant effect of the tissue removal. Extensive lymphatic tissue removal markedly reduced the serum antibody response to a small dose of sheep RBC antigen for both the primary and secondary responses. Relatively little recovery of ability to respond was seen with the primary response during the 18-day period of observation. Lymphatic tissue removal did not alter the serum protein electrophoretic mobility pattern. Little compensatory hyperplasia of residual or ectopic lymphatic tissue was seen at the completion of the experiments. Regeneration of lymphatic tissue did not take place at operative sites except near the pancreas where complete extirpation of lymph nodes was difficult to perform.
Mechanisms of calcification: role of collagen, polyphosphates, and phosphatase
Authors: Fleish Herbert , Neuman William F.
Published: December 2017

The nucleating properties of various collagens have been tested by determining quantitatively the minimum ion product, Ca times P, required to form calcium phosphate crystals. While most collagens require a product of 35 (mg%)2 or greater for calcium phosphate to precipitate, some collagens extracted from tendon induce mineralization at a product of 16 (mg%)2. Plasma ultrafiltrate contains one or more substances which increase this minimum ion product, and therefore inhibit calcium phosphate nucleation. These substances are inactivated by alkaline phosphatase. Finally, polyphosphates, both organic and inorganic, are highly inhibitory to calcium phosphate nucleation and precipitation. It is therefore suggested that at least two mechanisms may be necessary for a tissue to mineralize: 1) the formation of a nucleating collagen and 2) the presence of phosphatase for the local destruction of the inhibitor(s) present in plasma.
Slow potential variations of small intestine
Authors: Bortoff Alex
Published: December 2017

The various configurations of externally recorded slow waves from the small intestine of the cat are compared to those recorded intracellularly. It is shown that the slow waves represent periodic depolarizations of longitudinal muscle cells and that the flow of current associated with these depolarizations is similar to that in a core conductor. By recording monopolarly from a segment of intestine immersed in a volume conductor, slow waves are obtained having configurations ranging from those approximating the true time course and polarity of the intracellular slow wave to those approximating its second time derivative. This is shown to be a function of the pressure exerted by the electrode on the tissue. From a consideration of these results, plus those recently obtained by others, it is suggested that both "propagation" and synchronization of slow waves are manifestations of a modulation of slow wave discharge brought about either by electrotonic spread of current via low resistance intercellular pathways, or by voltage field effects.
Regulation of blood glucose concentration: response of liver to glucose administration
Authors: Landau Bernard R. , Leonards Jack R. , Barry Frank M.
Published: December 2017

Hepatic glucose output has been determined during the infusion of glucose in gradually increasing quantities into unanesthetized dogs with cannulas inserted in their aortas, hepatic veins and portal veins. Profound changes in hepatic response to the infusions were consequent to differences in the composition of the diets ingested by the dogs in the days prior to these experiments. Infusion of glucose into dogs maintained on a high protein diet resulted in a rise in blood glucose concentration, with a cessation of net hepatic glucose production only at hyperglycemic levels. In contrast, in carbohydrate-fed dogs the blood glucose concentration increased very little on glucose infusion, and there was a net uptake of glucose by the liver. Under these conditions the liver appears to play a dominant role in the regulation of the constancy of the blood glucose concentration, and the regulating mechanism appears to be particularly sensitive to small changes in glucose concentration.
Fructose as a precursor of amino acids in the lactating cow
Authors: Black Arthur L. , Luick Jack R. , Kleiber Max , Baxter Claude F.
Published: December 2017

The biosynthesis of amino acids from fructose and glucose uniformly labeled with C14 was studied in lactating cows. There were no major differences in the hexoses as precursors of amino acids, the injection of either hexose resulting in the formation of serine and alanine with highest specific activities. Amino acids from whey protein had the same C14 distribution as casein amino acids. Cystine was synthesized by the cow, but only to a small extent from fructose.
Initial stages of intermediary glucose catabolism in the hibernator and nonhibernator
Authors: Hannon John P. , Vaughan David A.
Published: December 2017

In the Arctic ground squirrel, hibernation caused a marked hypoglycemia and a twofold increase in myocardial and skeletal muscle glycogen, but had no effect on liver glycogen. When assayed at 30 C, hibernation led to a moderate increase in the glucokinase and glucose-6-phosphate dehydrogenase activity of the myocardium. Finally, it also caused a sharp reduction in the glucose-6-phosphate dehydrogenase activity and almost a complete obliteration of phosphorylase activity in the liver. Between species, the laboratory rat exhibited about 50% more myocardial glucose-6-phosphate dehydrogenase and about twice as much phosphorylase as the myocardium of the awake squirrel. The liver of the awake squirrel had about 50% more glucose-6-phosphatase, about 60% more phosphorylase, about twice as much glucokinase, and about four times as much glucose-6-phosphatase as the liver of the rat. A number of correlated enzyme activities were observed. The mechanisms underlying the hypoglycemia and net glycogen synthesis of hibernation and the species differences in carbohydrate metabolism and lipogenic capacity are discussed.
Effects of exercise on serum enzyme values and tissues of rats
Authors: Altland Paul D. , Highman Benjamin
Published: December 2017

Young adult rats were exercised in a rotating drum for 16 hr. Immediately after the exercise, there was a two-to sixfold increase in serum glutamic oxalacetic transaminase, serum glutamic pyruvic transaminase, serum lactic dehydrogenase, serum aldolase, and blood urea nitrogen, and a decrease in serum alkaline phosphatase. Recovery of different enzymes from these altered values occurred at different rates during a period of 1 to more than 6 days. The rats also showed a 13% loss in body weight and severe depletion of liver glycogen. Pathologic studies revealed an abundant deposition of fine fat droplets in skeletal muscle fibers, liver cells, and renal tubular epithelium and lipid depletion of the adrenal cortex. Some animals showed small foci of inflammation and necrosis in the muscle fibers. The pathologic lesions were transient and disappeared before complete return of the serum glutamic oxalacetic transaminase and serum aldolase values to normal levels.
Pressure-volume curves in live, intact dogs
Authors: Richardson Travis Q. , Stallings James O. , Guyton Arthur C.
Published: December 2017

The effect of changes in blood volume on mean circulatory pressure was studied in 10 dogs. Mean circulatory pressure increased linearly as the blood volume was expanded and decreased linearly as blood volume was lowered below the normovolemic level. For example, the mean circulatory pressure fell from a normal of 7 mm Hg down to 0 mm Hg when the animals were rapidly hemorrhaged 14.7% of their normal blood volume; when the blood volumes were expanded to 50% above normal, the mean circulatory pressure rose from the control value of 7 mm Hg up to 30 mm Hg. It is concluded that one of the major factors determining the mean circulatory pressure is blood volume.
Elimination of transient secretion of phosphate by alkalinization of plasma in dogs
Authors: Carrasquer Gaspar , Brodsky William A.
Published: December 2017

Sodium phosphate and creatinine (500 µmoles each) were injected instantaneously into the renal artery of dogs anesthetized with Nembutal. Urine flows of 6–12 ml/min and serum phosphate levels of 3–6 mm/liter were maintained for 1 hr preceding instantaneous injection. Dogs were divided into two major groups, based on steady state conditions imposed: a) systemic acidosis induced by infusion of NaH2PO4 and b) systemic alkalosis induced by infusion of Na2HPO4 + NaHCO3. Then, either NaH2PO4 or Na2HPO4 was injected close-arterially, and the transient excretory response (covering 3–5 min) was studied. The parameter for measuring renal function was the incremental excretion of phosphate per unit injected per one circulation through the kidney. This was compared to the simultaneous and identical parameter for creatinine, considered as a glomerular substance. During systemic acidosis, net transient secretion of phosphate was observed in 73% of the periods after H2PO4– injection, and in 19% of the periods after HPO4– injection into renal artery. During systemic alkalosis with formation of alkaline urine, net secretion was observed in 15% of the periods after HPO4– injection, and in none of the periods after H2PO4– injection into the renal artery. When paradoxical aciduria occurred during systemic alkalosis, net transient secretion was observed in 30% of the periods after HPO4– injection. Data show that the transtubular movement of H2PO4– ion is different from that of HPO4– ion. The possibility of tubular secretion of H2PO4– ion, as a mechanism of urine acidification, is discussed.
In vitro synthesis of C14-corticotropin by isolated rat anterior pituitary: effect of adrenalectomy
Authors: Wool Ira G. , Scharff R. , Mages N.
Published: December 2017

A method is described for the measurement of C14-corticotropin synthesis by isolated rat anterior pituitary tissue. Intact pituitary glands were incubated with C14-phenylalanine; carrier anterior pituitary powder (porcine) was added and corticotropin extracted with hot glacial acetic acid and purified with oxycellulose. The oxycellulose concentrate contained corticotropin (as measured by its ability to cause enlargement of the adrenal gland of hypophysectomized rats) and was free of C14-phenylalanine; on dialysis the radioactivity in the oxycellulose concentrate behaved like purified corticotropin. The rate of C14-corticotropin synthesis by isolated rat anterior pituitary was linear for 4 hr and was increased in pituitaries from adrenalectomized rats. Adrenalectomy did not increase amino acid incorporation into total protein of anterior pituitary; the effect of adrenalectomy was only apparent when pituitary protein was fractionated and oxycellulose concentrates prepared, which is for a specific biological effect of adrenalectomy on corticotropin synthesis.
Role of stomach in regulation of activities of hypothalamic feeding centers
Authors: Sharma K. N. , Anand B. K. , Dua S. , Singh Baldev
Published: December 2017

Gastric distention was produced through a water-filled-balloon system and the electrical activity of the hypothalamic "satiety" and "feeding" centers were recorded electroencephalographically through stereotaxically implanted electrodes. Gastric distention leads to production of high voltage irregular waves and occasional spikes, selectively in the region of the satiety centers. Gastric hunger contractions do not change the electrical activity of either feeding or satiety centers. Glucagon does not produce any direct effect on the hypothalamic centers or stomach contractions. Later, when glucagon raises blood glucose and arteriovenous Δ-glucose, activity of satiety centers increases and gastric contractions are inhibited. After lesions of satiety centers, rise in blood glucose with glucagon does not inhibit gastric contractions. Therefore, the inhibition of gastric hunger contractions is a result of activation of satiety centers by increased glucose utilization.
Response of ileal segment weight to prolonged levarterenol infusion
Authors: Estensen Richard D. , Gilbert Robert P.
Published: December 2017

Weighed segments of dog ileum were infused for 10–100 min with levarterenol at rates of 0.1– 96 µg/min. Although the response was unpredictable, in 13 of 22 trials the ileal segment gained weight and, in 12 of these trials, there was a rise in the small vein pressure. This rise in small venous pressure was considered indicative of constriction of veins central to the small vein. This could have increased capillary hydrostatic pressure so as to cause the gain in interstitial fluid which was indicated by the weight increase.
Autoprothrombin II of human origin
Authors: Ulutin Orhan N. , Johnson J. Frederic , Seegers Walter H.
Published: December 2017

Autoprothrombin II activity develops when prothrombin preparations of human origin are activated with purified thrombin at pH 8.2. Early during the activation an inhibitor seems to form. Concentrates of the autoprothrombin II can replace serum in the thromboplastin generation test provided platelets are used in the test, but not if a soy bean phosphatide is used. Dogs were given Coumadin in doses that lowered their own autoprothrombin concentration practically to zero. Then while continuing with use of the drug some purified autoprothrombin II was infused intravenously. This was tolerated very well. The autoprothrombin II concentration stayed at normal for 7 hr. In 24 hr none remained. The infusion was also followed by a shortening of the whole blood clotting time.
Effects of prenatal x-irradiation on motor performance in the rat
Authors: Werboff Jack , Goodman Irving , Havlena Joan , Sikov Melvin R.
Published: December 2017

Gravid albino rats of the Sprague-Dawley strain received either 25, 50, or 100 r whole-body X-radiation on either day 5, 10, 15, or 20 of gestation. Controls were sham-irradiated. Over 500 surviving offspring were evaluated on measures of motor maturation of the upright and righting responses, motor strength, and locomotor learning during the neonatal period. The results indicate that radiation exposure of 100 r on day 15 of gestation retards motor maturation of the upright and righting responses. Almost all of the radiation groups show a decrease in motor strength as compared to the control group with maximum deficits in the groups receiving 50 or 100 r on day 10 or 15 of gestation. On the locomotor learning measure, the results are not consistent, but the group receiving 100 r on day 15 of gestation is maximally affected. These deficits in motor performance are related to observable motor impairment. It is concluded that low levels of radiation received prenatally can have detrimental effects on the development of motor performances in the rat.
A possible correlation between ATPase activity and Na content of embryonic chick heart
Authors: Klein Richard L.
Published: December 2017

The water content of embryonic chick ventricles decreases gradually from 88% at 2 days of incubation to 83% shortly after hatching. Ventricular protein nitrogen decreases during early development and then increases rapidly at midfetal age until hatching, after which a more gradual increase continues. Magnesium-activated ATPase activity of whole ventricle homogenates at pH 7.0–7.5 is much greater than is the calcium-activated enzyme throughout development. A very marked increase in Mg-ATPase occurs between 4 and 7 days of incubation; a lesser increase occurs just prior to and after hatching. Calcium-ATPase increases gradually throughout development. Magnesium-ATPase has been identified with both isolated mitochondrial and microsomal fractions; Ca-ATPase is exclusively associated with the myosin fraction. Myokinase occurs in the supernatant. Optimal pH's are given for the enzymes. It is suggested that the initial rapid fall in ventricular Na content between 2 and 7 days of incubation is directly related to two events: disappearance of the cardiac jelly and establishment of an effective Na extrusion mechanism.
Hemodynamic correlates of the first heart sound
Authors: Di Bartolo Giuliano , Nunez-Dey David , Muiesan Giulio , MacCanon D. M. , Luisada Aldo A.
Published: December 2017

The temporal relationship between the "crossing" of equisensitive atrial and ventricular pressure tracings and the initial components of the first heart sound of the homolateral intracardiac phonocardiogram was analyzed in 35 dog experiments. These studies showed that the first component of the first heart sound followed the atrioventricular valve closure (AV crossing) in all instances by an average time interval of 23 msec and that, at the time of its occurrence, there was a ventricular-atrial pressure gradient of 5 mm Hg in the right side and of 14 mm Hg in the left side of the heart. It is concluded that valvular closure, per se, does not cause the first component of the first heart sound. Actually the first heart sound occurs later during the period of isometric ventricular contraction, suggesting that the rise of ventricular pressure is responsible for its vibrations. Comparative analyses of right and left intracardiac and external phonocardiograms showed that the right side component of the first heart sound follows the left in about three-fourths of the cases and is coincident with it in the remainder and that these events are reflected in the same order in the external phonocardiogram.
Effects of gamma radiation on isolated surviving arteries and their vasa vasorum
Authors: Smith Durwood J.
Published: December 2017

The effects of irradiation with Co60 on 136 swine and dog carotid arteries have been studied in vitro, utilizing an angioplethysmokymographic technique. In 20–40% of the specimens a slight vasoconstriction of the arterial wall was observed. This began and was completed within the first 60 sec of irradiation. Mounting the tissue in mineral oil did not prevent this reaction. Marked reductions in vasa vasorum flow were observed in swine carotids (70% decrease) and dog carotids (50% decrease) exposed to 9390 r of gamma radiation during 15 min. Less marked, although significant, decreases in vasa vasorum flow were seen in swine arteries exposed to 3000 r, 2085 r, and 1500 r. No significant decreases were observed in 24 arteries exposed to 843 r. Swine arteries exposed to 9390 r, while mounted in mineral oil, did not show a significant decrease in vasa vasorum flow. It is concluded that the contraction of the arterial wall was a direct effect of radiation upon the vascular smooth muscle and that the observed decrease in vasa flow was probably secondary to ionization of the Tyrode's solution surrounding the artery.
Protection by histamine and metabolites in anaphylaxis, scalds, and endotoxin shock
Authors: Fox Charles L. , Lasker Sigmund E.
Published: December 2017

The release of toxic factors has been implicated in the mechanism of shock from various forms of trauma. If histamine (H) released after anaphylaxis, endotoxin shock, or thermal burns is a lethal factor in mice, priming with (H) before injury would presumably enhance mortality. Mice were pretreated with (H) or certain metabolites prior to inducing shock via horse serum anaphylaxis, scald injury, or lethal dose of E. coli endotoxin. Large doses of (H) did not enhance mortality; actually, mortality from these three forms of shock was lowered by pretreatment with (H) or imidazoleacetic acid, but not by other metabolites tested. The data, while unexplained, do not appear to support hypotheses assigning an active role to (H) release in these three forms of shock in mice.
Insufficiency of O2 supply to pregnant uterus
Authors: Huckabee William E. , Metcalfe James , Prystowsky Harry , Barron Donald H.
Published: December 2017

Pregnant goats under anesthesia were studied while subjected to various degrees of hypoxemia. Lactate and pyruvate concentrations were determined in maternal arterial and uterine venous bloods and in umbilical arterial and venous bloods. The same highly heterogeneous values were found as reported for nonhypoxemic animals, and no clear systematic relationships could be discerned. However, when the values were viewed as being determined by exchanges of excess lactate on each side of the placenta, several patterns of metabolic activity were discernible. 1) No net anaerobic metabolism occurred in the pregnant uterus in the well-oxygenated mother. 2) When maternal blood oxygen was extremely low, anaerobic metabolism occurred in the fetus and in the uterus as a whole. 3) However, in the whole range of mild and moderate hypoxemia, the pattern consisted of production of excess lactate by the fetus and its reoxidation by the placenta; consequently, there was no net anaerobic metabolism by the pregnant uterus as a whole. Such fetuses, even when umbilical blood oxygen was virtually absent, survived and showed no signs of deleterious effect.
Liberation of antidiuretic hormone following hypothalamic stimulation in the dog
Authors: Fang H. S. , Liu H. M. , Wang S. C.
Published: December 2017

In 94 of 111 dogs, stimulation of the hypothalamus resulted in moderate to marked antidiuretic effects. The onset was slow (1/2–3 min) and the effect lasted for 15–35 min. These antidiuretic responses could be elicited by stimulating not only the points corresponding to supraoptic and paraventricular nuclei, but also a larger area in the hypothalamus. The antidiuretic action evoked by 20-sec excitation with stimuli of 7 v and 50 cycles/sec was roughly equivalent to that following intravenous administration of 2.5 mU/kg of Pitressin. Atropine and d-hyoscyamine did not block the antidiuretic responses to hypothalamic stimulation, but adequate amounts of n-ethyl-nortropinbenzhydrylether-hydrobromide and Dibenzyline did. The possible mechanism of such a phenomenon is discussed.
Pulmonary air embolism induced during experimental decerebration
Authors: Plum Fred , McNealy Donald E.
Published: December 2017

During experiments employing Sherringtonian decerebration, it was observed that cats which failed to demonstrate the expected postural responses often showed hyperpnea, widened arterial-alveolar CO2 gradients, and anoxemia. Autopsy revealed air in jugular veins and right heart, as well as heavy lungs. Analysis of surgical procedures revealed that pulmonary air embolism was favored by the following conditions: elevating the head above the thorax during craniotomy, widely removing temporal bone to expose diploic spaces along the tentorial margin, and light anesthesia. Conversely, air embolism was avoided if the head was kept at or below hindquarter level during surgery, bone edges were delicately removed and wax-sealed, care was taken to avoid tearing venous sinuses, and anesthesia was sufficiently deep to prevent gasping. When this latter technique was used, postoperative pulmonary ventilation and blood gases resembled control values. Pulmonary air embolism may explain some of the wide respiratory variations and physiological conditions reported to follow experimental decerebration and other procedures employing extensive craniectomy.
Minimal mass required for induction of a sustained arrhythmia in isolated atrial segments
Authors: West Theodore C. , Landa Jorge F.
Published: December 2017

With the aid of electrical stimulation and a combination of acetylcholine and physostigmine, an experimental arrhythmia was predictably induced in isolated atrial segments from rabbits. The tissue was from either left or right atrium, but was not spontaneously active. It was driven electrically at the rate of 2/sec. After the measurement of excitability and of conduction time, both in the presence and absence of ACh, an arrhythmia was induced. The tissue then was divided surgically and the procedure repeated until a residual segment was obtained which did not respond with an arrhythmia. The weight of the nonarrhythmic segment was determined and averaged 32 mg in 16 left atrial preparations, 28 mg in 10 right atrial segments, and 38 mg in 4 segments of left atrium from rabbits chronically treated with reserpine. Calculation of the mean conduction time and of the mean refractory period associated with induction of the experimental arrhythmia indicated that the observed minimal arrhythmic segment was approximately the mass theoretically required if the initiation and maintenance of the arrhythmia were dependent on re-entry excitation.
Evaluation of the gastric Na: H exchange mechanism using histamine and Diamox
Authors: Powell Don W. , Robbins Robert C. , Boyett June D. , Hirschowitz Basil I.
Published: December 2017

This study tested a theory of gastric secretion comprising: a) the secretion of Cl, as NaCl and KCl in water, from which b) an exchange of Na+ for H+ occurs. Thirty-one studies were made in eight unanesthetized dogs equipped with esophagostomy and gastric cannula. A 3-hr intravenous infusion of 1 mg histamine base/hour as the control experiment was modified in two ways—by the intravenous injection of 1 g of Diamox (D) either immediately before (D-H) or half-way through (H-D) the histamine infusion. Diamox (either D-H or H-D) reduced gastric [H+] by 50 mEq/liter and increased [Na+] by 44–50 mEqliter, and H:Na exchange fell from 95% to 70% with osmolality and [Cl–] relatively unaffected; but K+ secretion was markedly inhibited. Pepsin secretion was essentially unchanged. The output of Na (VNa) increased by 100% despite a 63% decrease in volume of gastric juice. The reciprocal Na:H changes without change in [Cl–] or osmolality, and the twofold increase in VNa support the concept of a Na:H exchange in the regulation of gastric [H+].
Role of hormones in glucose-6-phosphate dehydrogenase adaptation of rat liver
Authors: Tepperman Helen M. , Tepperman Jay
Published: December 2017

The hepatic enzymes glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase increase markedly in activity on refeeding after a 48-hr fast in the intact rat, but fail to do so in the hypophysectomized animal. Treatment with somatotrophin, cortisone, and thyroid hormone individually and in pairs failed to restore this adaptation to refeeding, but a combination of the three repaired the defect. Similar observations were made on increases in these enzymes in response to fructose feeding in ad libitum-fed hypophysectomized rats. Triple hormone-treated animals in which the enzyme increase in response to fructose feeding was restored were the only ones which gained weight. To rule out possible effects of variations in food intake as a determining factor in the response, hypophysectomized rats fed measured amounts of a starch-fructose diet by stomach tube were compared with suitable controls. A striking increase in enzyme activity occurred in these animals even when no hormone treatment was given, and no additional increase could be induced by treating with the three hormones. It is concluded that the liver cell of the hypophysectomized rat has an autonomous capacity to modify its enzyme profile selectively without the direction or support of hormones of pituitary origin. These hormones may exert their effects in ad libitum-fed animals by influencing food intake and intestinal hexose absorption rates.
Method of obtaining arterial elastic coefficients in totally perfused animals
Authors: Johnson John A. , Read Raymond C. , Kuida Hiroshi
Published: December 2017

Calculations of arterial elastic coefficients of dogs under conditions of total body perfusion have been made by utilizing the pressure data obtained from steady state perfusion and inflow stoppage. This was done by finding the first derivative of the pressure-time curve after inflow stoppage and evaluating this at the starting time of the transient. This "zero" time slope gave the value of the elastic coefficient divided by the resistance at the instant of inflow stoppage, and multiplying this ratio by the resistance evaluated from the immediately preceding steady state conditions gave an estimate of the elastic coefficient, E, of the arterial tree. Drugs were used to alter the resistance, and this permitted an estimate of E under various conditions. The value of E appeared to be a function of arterial pressure, and the value at a pressure of 124 mm Hg was 4,080 dynes/cm5.