bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of estrogen on composition and function of cardiac muscle
Authors: King T. M. , Whitehorn W. V. , Reeves B. , Kubota R.
Published: December 2017

In vitro tension development is significantly reduced in surviving left ventricular columnae carneae and ATP treated glycerol extracted fibers of ovariectomized albino rats. This reduction in contractility is paralleled by decrease in ventricular actomyosin content. Heart-body weight ratio, myocardial water content and total protein concentration are not abnormal. No changes in excitability or refractoriness of surviving bundles of castrate animals were found. Treatment with alpha estradiol, 0.1 µg/day, returned tension production and actomyosin concentration to the normal range. It is concluded that the contractile system of cardiac muscle, like that of the uterus, is dependent on estrogen. These data suggest a general action of the hormone on contractile protein synthesis in all types of muscle and have important implications regarding cardiac and other muscular functions.
Effect of vitamin E deficiency on creatine phosphokinase of heart and skeletal muscle
Authors: Read W. O. , Nehorayan Said
Published: December 2017

A quantitative determination of creatine phosphokinase activity of heart and skeletal muscle has been made in early and severe vitamin E deficiency in the rabbit. This study revealed that early vitamin E deficiency resulted in an increase in creatine phosphokinase activity of skeletal muscle but decreased the enzymatic activity of the heart. Severe vitamin E deficiency resulted in a decrease in creatine phosphokinase activity of both skeletal and heart muscle. 17-Hydroxycorticosterone, in small doses, resulted in an increase in enzymatic activity of skeletal muscle but no change in heart muscle. Large doses of 17-hydroxycorticosterone caused a decrease in the creatine phosphokinase activity of both heart and skeletal muscle. Normal male rabbits exhibited a lower enzymatic activity than female animals, a difference which, in part, was due to testosterone.
Comparison of cardiac monophasic action potentials recorded by intracellular and suction electrodes
Authors: Hoffman B. F. , Cranefield P. F. , Lepeschkin E. , Surawicz B. , Herrlich H. C.
Published: December 2017

The action potentials recorded from heart muscle with a suction electrode have been compared to those recorded with an intracellular microelectrode. It has been found that if the suction electrode is properly used the monophasic potentials recorded with it may be taken as a reliable index of the time of arrival of excitation at the electrode and as a reliable index of the shape of the action potential during the entire phase of repolarization. The suction electrode potentials differ from the microelectrode potentials in showing a lower rise velocity, a smaller amplitude, a quantitatively different reversal or overshoot and, in the beating heart, ‘afterpotentials’ caused by mechanical effects. When the shape of the action potential, as observed with the microelectrode, is changed by ions such as K+ or Ca++ a similar change is observed in the potential recorded with the suction electrodes.
Effect of potassium and calcium deficiency on the monophasic action potential, electrocardiogram and contractility of isolated rabbit hearts
Authors: Surawicz B. , Lepeschkin E. , Herrlich H. C. , Hoffman B. F.
Published: December 2017

Isolated rabbit hearts were perfused with Krebs-Henseleit solution deficient in K, Ca or both. Ventricular monophasic action potentials registered with the suction electrode, electrocardiograms and intraventricular pressures were recorded simultaneously for periods up to 20 minutes. Perfusion with K-deficient solutions resulted in a brief initial prolongation of the entire descending limb of the action potential and of the T wave, followed by progressive increase in slope of the initial portion and decrease in slope of the terminal portion of the action potential. During this time the T wave became shorter and a U-wave-like deflection occupying the entire diastole developed. QRS showed progressive prolongation. Finally, A-V conduction disturbances, ectopic beats and ventricular fibrillation developed. The force of contraction increased slightly. Perfusion with Ca-deficient solutions decreased the slope of the initial portion while increasing the slope of the terminal portion of the action potential. This was accompanied by prolongation of the ST- segment and reversal in the direction of the T wave. The duration of the action potential reached a maximum after 40–80 seconds of perfusion, while the force of contraction decreased progessively. Perfusion with solutions without potassium and calcium prolonged the initial as well as terminal portion of the action potential.
Relation of thyroid to gastric acid secretion in the anesthetized rat
Authors: Goldsmith Dale P. J. , Nasset E. S.
Published: December 2017

The amount of free gastric acid secreted after methacholine stimulation was studied in anesthetized rats. Desiccated thyroid elevated the metabolic rates of normal rats 45% and reduced free acid secretion. Thyroparathyroidectomy (3–5 weeks postoperative) did not change secretion from that of controls. Thyroparathyroidectomized rats made euthyroid by thyroxine or desiccated thyroid had reduced secretions. Serum calcium was decreased in all treated groups. Serum phosphate and adrenal gland weights were increased in normal, thyroid-fed rats. Thymus gland weights were unchanged.
Effects on cats of conductive hypothalamic cooling
Authors: Freeman Walter J. , Davis Donald D.
Published: December 2017

Conductive heating in the physiological range of sites in the anterior hypothalamus of the anesthetized cat caused a fall in rectal temperature and inhibition of shivering. Excessive heating caused also cutaneous vasodilatation, bradycardia and transient loss of nociceptive reflexes. Cooling at the same sites caused a rise in rectal temperature but did not cause shivering or cutaneous vasoconstriction. Heating of the posterior hypothalamus in the physiological range was associated with a slight rise in rectal temperature, and cooling with a slight fall. Changes in autonomic and somatic activity were rarely seen in association with such heating and cooling. In chronic preparations heating and cooling of sites in the anterior hypothalamus caused appropriate vasomotor and postural changes, whereas heating and cooling of sites in the posterior hypothalamus did not. It is concluded that receptors for both heat and cold are located in the anterior hypothalamus but probably not in the posterior hypothalamus.
Effect of a peripheral arteriovenous fistula on coronary blood flow and cardiac oxygen metabolism
Authors: Glaviano Vincent V. , Nykiel Florian
Published: December 2017

In anesthetized open-chest dogs, the mean blood pressure, cardiac output and coronary sinus flow were measured before and after opening of a unilateral or bilateral femoral arteriovenous fistulae. The opening of an A-V fistula was accompanied by a decrease in mean blood pressure and an increase in cardiac output and coronary sinus flow. Approximately 20 seconds after the fistula was opened, the coronary sinus flow established itself at a level independent of the per cent change in mean blood pressure and cardiac output. Opening of an arteriovenous fistula was also followed by a significant increase in myocardial oxygen consumption, work, and in most experiments by an increase in cardiac efficiency. During periods of opened-fistula the augmented myocardial oxygen consumption was accompanied by a spread of the arterial-coronary sinus oxygen difference.
Sympathetic influences during hemorrhagic hypotension
Authors: Walton R. P. , Richardson J. A. , Walton R. P. , Thompson W. L.
Published: December 2017

Hemorrhagic hypotension was observed for several hours in open-chest dog preparations under pentobarbital anesthesia. Heart force, as recorded from a strain gage arch on the right ventricle, followed a pronounced upward trend above control levels in some cases while in others there were variable grades of cardiac depression. Plasma epinephrine levels progressively increased, reaching extreme values at terminal stages; norepinephrine levels were only moderately increased. Force and pressor responses to injected norepinephrine progressively decreased in association with progressive acidosis. Following interruption of sympathetic pathways with extradural procaine infusions or with ganglionic blocking agents, hemorrhage caused less pronounced increments in heart force and catechol amine levels while responsiveness to injected norepinephrine was better maintained.
Changes in concentration of histamine in canine gastric mucosa during secretion
Authors: Hill Richard W. , Code Charles F.
Published: December 2017

A study was undertaken to determine whether the concentration of histamine in the gastric mucosa changes with feeding, with histamine or vagal stimulation, or after the administration of cortisone. The concentration of histamine in the gastric mucosa was determined in dogs in the fasting state, after ingestion of a meal, after a meal followed by the injection of histamine, during insulin-induced hypoglycemia, and after administration of cortisone. Comparison of the different groups with the fasting series disclosed that no significant change in the mucosal concentration of histamine occurred after the meal, after the meal plus injections of histamine, or after administration of cortisone. Insulin-induced hypoglycemia caused a rise in the concentration of histamine in the mucosa of the body and antrum of the stomach.
Effects of thyroid and adrenal cortical hormones on restoration of liver protein and enzyme activity after partial hepatectomy in rats
Authors: Tipton Samuel R. , Majors C. W. , Smothers J. L.
Published: December 2017

Propylthiouracil depressed and thyroxine elevated the succinoxidase activity of rat liver after 4 days of regeneration. Protein-depleted animals had a significant decrease in activity of succinic dehydrogenase and cytochrome oxidase, rate of restoration of liver mass, enzyme activity and new protein. Thyroxine increased the rate of regeneration and the enzyme activity even in protein-depleted animals. Adrenalectomized rats on low protein intake had a very low rate of regeneration and protein replacement and low amounts of new enzyme activity and new protein after partial hepatectomy. Increasing the dietary protein to 36% increased all of these factors significantly, but administration of cortisone or adrenal cortical extract, had little effect on enzyme activity even though its effect on protein restoration was about as good as that of the high protein intake. Apparently under certain conditions, these hormones can produce changes in specific enzyme proteins that are independent of changes in total cell protein.
Intestinal absorption of methionine and histidine by the chicken
Authors: Paine C. M. , Newman Howard J. , Taylor M. Wight
Published: December 2017

Intestinal absorption of methionine and histidine was studied in adult chickens having permanent Thiry-Vella fistulas. The l isomers of both amino acids were absorbed from the fistulas more rapidly than were the d isomers. At a concentration of 10–3 m, 2,4-dinitrophenol retarded absorption of l-methionine but not of the d form. The absorption of l-histidine was impaired in the presence of equimolar concentrations of either l- or d-methionine. Racemization of d-methionine during absorption could not be demonstrated. The l isomers of both methionine and histidine appear to be absorbed from the chicken intestine by a common specific transport mechanism, with d-methionine being able to participate in at least one stage of this mechanism.
Magnesium metabolism in rabbits using Mg28 as a tracer
Authors: Aikawa Jerry K. , Rhoades Eloise L. , Harms Dale R. , Reardon Jacqueline Z.
Published: December 2017

Tracer doses of Mg28 were used to study the metabolism of parenterally administered magnesium. Plasma clearance was rapid, and accumulation of radioactivity in bone started within 2 hours. Of the tissues studied, skin and muscle showed the lowest concentrations of Mg28. In most tissues the ratio of tissue to serum radioactivity became fairly constant after 18 hours. The values for the exchangeable body pool of magnesium, calculated from the specific activities of urine specimens obtained between 18 and 24 hours, approximated the carcass content of magnesium. During starvation the renal excretion of endogenous magnesium amounted to 61.7 mEq/kg of weight loss.
Effects of glucagon and tolbutamide on glycogen in isolated perfused rat liver
Authors: Miller Leon L. , Sokal Joseph E. , Sarcione Edward J.
Published: December 2017

The glycogen content of the isolated perfused liver taken from fed normal rats is remarkably stable for 3–6 hours ( Am. J. Physiol. 195: 295, 1958) and thus affords an isolated system for studies of the effect of various agents on glycogen synthesis and glycogenolysis. The effects of glucagon and tolbutamide in this system are described. Glucagon given by continuous infusion (30–225 µg/hr.) caused prompt glycogenolysis, with blood glucose concentrations rising to levels as high as 970 mg%. Hyperglycemia of 600–700 mg% did not inhibit the glycogenolytic action of glucagon; however, at glucose levels of 800– 1000 mg% glycogenolysis did not proceed to completion. High concentrations of tolbutamide, maintained before and during administration of glucagon, failed to inhibit the glycogenolytic action of the latter agent.
Tissue pressure as a causal factor in the autoregulation of blood flow in the isolated perfused kidney
Authors: Hinshaw Lerner B. , Day Stacey B. , Carlson Curtis H.
Published: December 2017

Experiments were performed on isolated perfused dog kidneys to determine relationships between tissue pressure, vascular volume, ‘over-all’ and ‘intraorgan’ vascular resistances. Results indicate that autoregulation of renal blood flow is brought about by disproportionately large increases in extravascular pressure. Since extravascular and intravascular pressures are opposing forces there is progressively less vascular distention with increases in arterial pressure as the increments in extravascular pressures approach the increments in intravascular pressures. The effective propellent force of blood flow through the kidney is thought to be the difference between the renal artery pressure and extravascular pressure. Vascular resistances calculated on this basis showed no significant changes throughout the range of autoregulation in four of the six experiments. It is proposed that the extravascular pressure within Bowmans capsule may exceed the renal interstitial pressure, and when the effects of renal extravascular pressures within and without Bowman's capsule are taken into account in the calculation of intrarenal vascular resistance, the pressure-flow relations of the kidney will be similar to those of other vascular beds.
Localization of renal calcium transport; effect of calcium loads and of gluconate anion on water, sodium and potassium
Authors: Howard P. Jay , Wilde Walter S. , Malvin Richard L.
Published: December 2017

We have performed a first series of experiments using our stop flow technique to localize renal transport of calcium in dogs. Calcium is found to be actively reabsorbed in a far distal area but does not appear to be actively lowered in concentration in proximally derived samples. In a second series of dogs, elevation of plasma calcium by infusion of the salt CaCl2 caused a 43% reduction in the additional volume of water reabsorbed by the proximal tubule during stop flow. Calcium does not interfere with the active reabsorption of sodium in the distal area and does not cause significant increases in sodium excretion. In contrast calcium causes a considerable increase in potassium secretion at a far distal site. When calcium gluconate was employed, severe impairment of distal sodium and calcium reabsorption occurred in addition to the increased potassium secretion. We suggest that the gluconate anion restricts the movement of sodium, calcium and potassium electrostatically thus obligating cations to remain in the tubular urine depending upon their reabsorption potential.
Long-term observations on relationship between food and water ingestion in the dog
Authors: Cizek Louis J.
Published: December 2017

Studies of the food-water intake relationship were made on 18 dogs over a period of 7 years. Single observations proved to be without value because of the considerable day-by-day variations that occur despite controlled diet and environmental conditions. The mean of multiple successive observations results in data which are consistent for the same animal over periods of at least 3–4 years. Such data reveal a quantitative linear relationship between food and water intakes provided the composition of the diet is maintained constant. Alterations in this relationship readily occur as a result of alterations in either the salt or water content of food. When the water content of the diet is changed, drinking is accurately readjusted so that the total intake for a given amount of food remains constant. Food deprivation results in a prompt and marked drop in daily drinking, the latter however, gradually increasing as deprivation continues. The immediate and delayed factors that might be concerned in this food-water relationship are discussed.
Localization and retention of triolein I131 in various tissues of the atherosclerotic rabbit
Authors: Felton Leland , Friedman Meyer , Byers Sanford O. , Cady Paxton
Published: December 2017

The rate of disappearance of intravenously injected triolein I131 from the blood stream and its concentration in various tissues were studied both in the normal and in the atherosclerotic rabbit. No difference in the rate of disappearance of the I131 from blood was observed between the normal and atherosclerotic rabbit. The atherosclerotic aorta was observed to take up approximately twice as much I131 as normal aorta when the tissues were assayed 10 minutes after injection. However, 24 hours after injection no essential difference was observed. All other tissues examined (fat, adrenal, spleen and liver) were observed to take up and retain more I131 than either the normal or the atherosclerotic aorta. The results suggest that the atherosclerotic aorta of the rabbit, while taking up initially more I131 than the normal aorta, appears to metabolize or otherwise rid itself of such I131 as rapidly as the latter in a period of 24 hours.
Changes in ovarian follicle composition with plasma levels of snakes during estrus
Authors: Dessauer Herbert C. , Fox Wade
Published: December 2017

The first stage of follicle development was due chiefly to hydration; during the second (deutoplasmic) stage 60 mg of solid were taken up with each 100 mg increase in follicle weight. Plasma calcium and protein P rose near end of hydration stage, remained elevated during deutoplasmic stage, reached extreme levels (max. Ca = 90 mm/l.; protein P = 86 mm/l.) near ovulation, and generally fell to anestrous levels while eggs were in early cleavage. Calcium increased in proportion to protein bound P of both plasma and follicles. During deutoplasmic stage a phospho-lipoprotein, of similar gross composition to yolk protein, appeared in plasma. Liver weight increased during hydration stage, remained elevated throughout deutoplasmic stage and decreased near ovulation. Fat body weight increased with onset of estrus, reached maximum during hydration stage and progressively decreased during deutoplasmic stage. Plasma and liver changes characteristic of estrus were reproduced in fasted male snakes with estradiol injections.
Subacute and chronic effects of hypothalamic lesions on aldosterone and sodium excretion
Authors: Davis James O. , Bahn Robert C. , Ball Wilmot C.
Published: December 2017

Effects of hypothalamic lesions were studied in 10 dogs with chronic ascites produced by constriction of the thoracic inferior vena cava. During the first three postoperative days, the high rate of urinary aldosterone excretion and the marked Na retention characteristic of dogs with chronic experimental ascites were unaltered in all 10 animals. Every area of the hypothalamus was destroyed bilaterally in at least one animal. Seven of the 10 dogs survived the subacute 3-day period; two dogs died after 6 days but five animals lived for 2 weeks or longer. In these seven animals, aldosterone excretion in urine remained elevated above normal although in three animals a progressive decline occurred; sodium excretion remained low in all seven dogs surviving the subacute period. In the three animals in which aldosterone output declined, there was bilateral injury of the median eminence and adrenal atrophy. The data show that chronic hypothalamic lesions were without effect unless the median eminence was injured.
Blood lipids, clotting and coronary atherosclerosis in rats exposed to a particular form of stress
Authors: Uhley Herman N. , Friedman Meyer
Published: December 2017

A group of rats fed a diet high in fat and cholesterol was exposed to a specially designed cage inducing a particular form of stress. Such rats at the end of 10 months exhibited a greater degree of hypercholesteremia and hyperlipemia than the control animals. In addition, considerably more coronary atherosclerosis was observed in the experimental than in the control group.
Effect of Nembutal on circulating and tissue blood volumes and hematocrits of intact and splenectomized mice
Authors: Friedman Julius J.
Published: December 2017

The effect of Nembutal on the circulating and tissue blood volumes and hematocrits was calculated by means of independent determinations of plasma and red cell volumes. Nembutal produced an increase in circulating blood volume accompanied by a reduction in the venous hematocrit. The blood volumes of liver, kidney, spleen and intestine rose following the administration of Nembutal, while the hematocrits of liver, lung, intestine and muscle declined, and that of kidney rose. The administration of Nembutal to splenectomized mice produces similar changes. The relationship of these alterations to changes in periphero-vascular tone are discussed.
Alternative mechanism of cardiac acceleration in Bainbridge's infusion experiments
Authors: Pathak C. L.
Published: December 2017

Intravenous infusions on intact dog hearts both in closed- and open-chest experiments indicate that a rise in the intra-atrial pressure is accompanied by either a positive, a negative or a no chronotropic effect, irrespective of the integrity of vagi. Positive chronotropic effects of similar intensity were also obtained even after bilateral vagotomy, topical application of cocaine or parenteral administration of atropine, tetraethylammonium or hexamethonium compounds. Moreover, the rise in the intra-atrial pressure or the degree of visible distention of the right atrium was not necessarily associated with a parallel rise in the heart rate. Thus, the infusion acceleration response obtained with some infusions only, fails to fulfill the requirements of a reflex action. There is, therefore, no justification for labeling it as a "reflex" effect, as advocated by Bainbridge. The chronotropic effects of the infusions seem to be due to stretch-induced alterations in impulse generation as a result of changes in the intra-atrial pressure and possibly depend upon the initial conditions at the pacemaker.
Microelectrode study of superior olivary nuclei
Authors: Galambos Robert , Schwartzkopff Johann , Rupert Allen
Published: December 2017

The superior olivary nucleus of barbiturate anesthetized cats was explored with microelectrodes. Both slow wave and single unit activity was recorded to clicks, tones and noise delivered to the two ears. The several segments of the superior olivary complex (e.g. the n. accessorius and n. trapezoid body, to mention 2 of the 5) are differently innervated from the two ears, and the physiological findings correlated well with the known anatomical data. In response to tones most units displayed a best frequency and a response area here as elsewhere in the auditory system. Intensity increase aroused more activity from most units and brought additional ones into action, but several important exceptions to this rule were studied. Units in n. accessorius proved to be exquisitely sensitive to whether the right ear or the left was stimulated first by paired clicks; the unique physiological and anatomical characteristics of these cells seem relevant to the binaural sound localization problem. Several lines of evidence, finally, suggest the existence of a class of units concerned chiefly with preserving the exact time of arrival of stimuli at the cochlea, this class being different in important ways from those dealing with tone-frequency mediation.
Pharmacologic differences of similarly electrogenic neuraxial sites of the bullfrog
Authors: Sigg Ernest B. , Grundfest Harry
Published: December 2017

Surface-negative potentials of long duration were evoked in the spinal cord, optic tectum, olfactory bulb and olfactory epithelium of frogs by appropriate stimuli. These responses were differently sensitive to the differently acting amino acid drugs and to d-tubocurarine. The spinal cord negativity was reversibly eliminated by topical application of γ-aminobutyric acid (C4). It was not affected by the longer-chain ω-amino acids (C6 or C8) nor by d-tubocurarine. The negativity of the optic tectum was eliminated by all these drugs, but early spike activity remained. Transient ‘spontaneous’ activity occurred after C6 or C8 were topically applied to the tectum. The tectal response to stimulating the retina with light was not affected by applying the drugs to the retinal surface itself. The responses recorded in the olfactory bulb by stimulating the nerve, and the responses of the olfactory epithelium to odoriferous stimuli were not affected by any of the testing drugs. Pharmacologic specificity of potentials which have similar appearances is thus demonstrated.
Effects of different frequencies of stimulation of sciatic nerves on the patellar reflex
Authors: De Salva Salvatore , Oester Y. T.
Published: December 2017

The patellar reflex was recorded every 10 seconds in cats under high cervical spinal section. The effects of different frequencies of electrical stimulation on both the ipsilateral and contralateral sciatic nerves were studied. At frequencies of 1–10/sec., contralateral sciatic nerve stimulation produced a depression of the patellar reflex. Frequencies of 20–120/sec. produced augmentation of the reflex. Stimulation of the ipsilateral sciatic nerve, through the same range of frequencies, only produced a gradient depression of the patellar reflex. The effect of pentobarbital on these reflexes in the same type of high cervical spinal cat was noted. The effects of frequency of stimulation, as well as anesthetic used, must be considered in using this reflex preparation.
Acute effect of changes in renal arterial pressure and sympathetic blockade on kidney function
Authors: Langston Jimmy B. , Guyton Arthur C. , Gillespie William J.
Published: December 2017

The effect of varying the renal arterial pressure on kidney function has been studied before and after complete spinal anesthesia. It is concluded that an increase in renal arterial pressure between 60 and 300 mm Hg always results in an increase in renal blood flow, glomerular filtration rate and urine formation, and that filtration rate and urinary output are related to renal arterial pressure in a linear fashion at pressures above 120 mm Hg. Sympathetic blockade, accomplished by complete spinal anesthesia, resulted in a higher rate of urine formation and renal blood flow but not of glomerular filtration rate at each level of arterial pressure than before the spinal anesthesia was administered. Since the sympathetic blockade was not followed by an increase in glomerular filtration rate, it is concluded that the diuresis which followed this blockade resulted from a decrease in reabsorption of glomerular filtrate.
Influence of sodium pentobarbital on splanchnic blood flow and related functions
Authors: Evringham Ann , Brenneman Edith M. , Horvath Steven M.
Published: December 2017

Eleven mongrel dogs were trained to lie quietly while splanchnic blood flows and splanchnic metabolisms were determined. They were then anesthetized by means of intravenous injection of 28.4 mg/kg of sodium pentobarbital and studies of the hepatic circulation continued for an additional 70 minutes. Only minor, transitory alterations were observed in the parameters being measured. It was concluded that with this particular anesthetic agent splanchnic blood flows and oxygen consumption were essentially at control unanesthetized levels within 30–45 minutes postanesthesia.
Portal and peripheral blood ammonia concentrations in germ-free and conventional guinea pigs
Authors: Warren Kenneth S. , Newton Walter L.
Published: December 2017

Portal and peripheral blood ammonia concentrations were measured in germ-free and conventional guinea pigs maintained on autoclaved stock diet containing approximately 20% protein, and in animals maintained on protein-free or high (40%) protein diets a few days before study. While there was considerable variation, the portal blood ammonia concentrations of germ-free animals averaged about one-fourth those of the conventional animals. In the latter, portal ammonia concentrations increased markedly with increases in dietary protein. Smaller, but significant, increases also occurred in the germ-free animals on diets with increased protein content. In the conventional animals the peripheral blood ammonia levels increased, with increases in the portal levels. The net effect was a relatively constant peripheral/portal ammonia level ratio of about 0.1, regardless of diet. In the germ-free animals, the peripheral levels remained rather constant, with the result that this ratio decreased from approximately 0.7 in animals on the protein-free diet to about 0.2 on the 40% protein diet. Possible relationships between the peripheral and portal blood ammonia concentrations are discussed.
Effect of hypothalamic lesions on renal excretion of sodium
Authors: Keeler R.
Published: December 2017

Electrolytic hypothalamic lesions in the area of the paraventricular nuclei were followed by a threefold increase in urinary sodium excretion during the 24-hour period after operation. Renal denervation or bilateral adrenalectomy did not modify this response. Total hypophysectomy reduced but did not abolish the natriuresis. Paraventricular lesions reversed the antinatriuresis which normally follows depletion of extracellular fluid volume. The lesions had no apparent effect on potassium excretion.
Glucose-6-phosphate dehydrogenase and renin in kidneys of hypertensive or adrenalectomized rats
Authors: Hess R. , Gross F.
Published: December 2017

Using a histochemical method, moderately strong glucose-6-phosphate dehydrogenase activity can be demonstrated in the macula densa of the distal tubules in the normal rat kidney. In rats rendered hypertensive by overdosage with cortexone (DOC) and saline, this enzymatic activity was found to decrease almost to zero within 4 weeks. This change was more marked in unilaterally nephrectomized animals than in intact rats. Measured by bioassay, the renin content of kidney extracts from the same animals was found to decrease simultaneously with the loss of enzymatic activity in the macula cells. The reverse effect, a marked increase in activity of the macula densa, was obtained in adrenalectomized animals. It is suggested that both the macula densa cells and the juxtaglomerular apparatus are parts of a system which respond similarly to changes in sodium balance and which may be related to the formation of renin.
Liver function in regenerating rat liver. CrPO4 colloid uptake and bile flow
Authors: Leong George F. , Pessotti Rita L. , Brauer Ralph W.
Published: December 2017

Functional changes in the regenerating hepatic tissue as indicated by CrPO4 colloid extraction and bile secretion by the isolated rat liver preparation were studied. Following partial hepatectomy, the liver weight/body weight ratio of the operated rats is significantly lower than the nonoperated controls. This is attributed to only a 80–85% restoration of the residual hepatic tissue. A transient increase in bile secretion/ unit weight of liver by 50% above the preoperative level occurs within 48 hours after partial resection. The uptake of radioactive chromic phosphate colloid indicates an increase in Kupffer cell activity (phagocytic functions) to values 200% above control within 48 hours. This function, however, is sustained and remains elevated for at least 90–100 days postoperatively. Histological evidence indicates that the increased Kupffer cell activity is probably due to an increase in cell population of phagocytic cells. Theoretical considerations for these changes in specific function of regenerating hepatic tissue and their relation to normal resting liver are discussed.
Lipid absorption: palmitic acid-1-C13 and tripalmitin-carboxyl C14
Authors: Burr William W. , McPherson James C. , Marcia John A. , Tidwell Herbert C.
Published: December 2017

Palmitic acid-1-C13 and tripalmitin-carboxyl C14 dissolved in olive oil were administered orally to previously fasted rats. The animals were sacrificed at 1, 2 and 3 hours after the administration of the doubly labeled lipid and the lipids were recovered separately from the stomachs and small intestines. The presence of each isotope in the lipid-fed and in that recovered was measured. The intestinal lipids showed a marked decrease in the excess of C13. The C14 label was considerably reduced in specific activity, but not to a comparable extent. The data appear best explained by a combined process of selective absorption of the free fatty acids and dilution with endogenous lipids. When C13- and C14-labeled palmitic acids were administered to an animal to determine whether any isotope effect might influence the results, a decrease in isotope content was observed; however, no change occurred in the ratio of the two isotopes.
Release and replenishment of acetylcholine in intestinal wall of guinea pig
Authors: Hayama Toyoaki , Ikeda Miyoshi
Published: December 2017

The total acetylcholine (ACh) content of the guinea pig ileum decreased (10–20%) immediately after circumferential stretching. Morphine was found to inhibit the decrease in the ACh content, while smooth muscle stimulants (ACh, histamine and KCl) exhibited no remarkable effect on the process. After ceasing the stretching the ACh content was restored within 15 seconds to the initial level. Successive peristalses also were found to result in a decrease in the ACh content of the intestinal wall. In relation to the circumferential stretching of the intestinal wall, a possible scheme of the sequence of reactions, comprising rapid release of ACh followed by decomposition and resynthesis, occurring during the course of stretching and relaxing of the intestine, is discussed.
Cardiovascular actions of histamine and potassium
Authors: Hanna Calvin , McHugo Patricia B. , MacMillan William H.
Published: December 2017

The cardiovascular actions of intravenous histamine, in doses from 2.5 to 20 µg/kg of the free base, were studied in the pentobarbitalized dog using the dye dilution method. With the small dose there was a consistent but small initial increase in cardiac output and with the larger doses there was a biphasic change in output. Cardiac rate, central venous pressure, central blood volume, hematocrit and the mean circulation time were essentially unchanged. Infusions of histamine and of potassium chloride at the rate of 1 µg and 1 mg/kg/min., respectively, moderately increased the cardiac output. Potassium chloride had no effect on the arterial blood pressure, cardiac rate and central venous pressure. Both the infusion of potassium chloride and injection of histamine produced a comparable elevation of the plasma potassium. It is possible that the actions of histamine to increase the plasma potassium contribute to the cardiovascular actions of this amine, especially on the cardiac output.
Phosphorylase and glycogen levels in skeletal muscle and liver of hibernating and nonhibernating bats
Authors: Leonard Samuel L. , Wimsatt William A.
Published: December 2017

Determinations of skeletal muscle and liver glycogen concentration and active a and total t phosphorylase activities were made in bats ( Myotis lucifugus) hibernating at 3°–5° and 20 hours after arousal at room temperature. After arousal, liver glycogen was decreased by half and muscle glycogen was increased over twofold. Concomitantly, muscle phosphorylase a was increased, phosphorylase t was unchanged and the ratio a/t was increased. In the liver, phosphorylase a, t and the ratios were increased upon arousal (calculated per unit of wet weight and per mg N). Epinephrine treatment was ineffective in the torpid hibernating bats, but in aroused bats, it decreased muscle and liver glycogen but increased muscle phosphorylase activity ratios only slightly. Histamine was ineffective in the aroused bats. Stimulating aroused bats to fly for short periods consistently resulted in lower muscle glycogen levels and in no change in muscle phosphorylase activity ratios. It is concluded that a) at least part of the increased muscle glycogen in the aroused bats comes from the liver, b) the changes in glycogen levels and phosphorylase activity are in some manner related and c) liver phosphorylase changes upon arousal, unlike that in muscle phosphorylase, involves an increase in total enzyme potential.
Metabolic changes in heart muscle during anoxia
Authors: Michal Gerhard , Naegle Siegfried , Danforth William H. , Ballard Fred B. , Bing Richard J.
Published: December 2017

The studies reported deal with the effects of varying periods of complete myocardial anoxia on the concentrations of reduced and oxidized diphosphopyridine nucleotide, reduced and oxidized triphosphopyridine, glycogen, adenosine triphosphate, hexose monophosphate, phosphocreatine and inorganic phosphorus in heart muscle. Oxygen lack leads to rapid dephosphorylation of high energy phosphate compounds and to the formation of inorganic phosphorus. The decline of adenosine triphosphate in heart muscle was more rapid than the diminution in the Qo2 of heart muscle slices reported previously. There was considerable glycogenolysis. The rate of glycogen breakdown did not appear to depend upon the amount of glycogen present in heart muscle until very low levels were reached. Prior to the onset of anoxia, most of the diphosphopyridine nucleotide was in its oxidized form. This oxidized form of diphosphopyridine nucleotide and reduced triphosphopyridine nucleotide decreased with time, while reduced diphosphopyridine nucleotide increased. The total concentration of diphosphopyridine nucleotides in heart muscle diminished.
Evidence for left ventricular diastolic suction in closed-chest dogs
Authors: Scheu Heiner , Hamilton W. F.
Published: December 2017

The question of ventricular filling by "suction" was investigated by recording the transmural ventricular pressure in normally breathing animals who had recovered from surgery. This transmural pressure was recorded as the difference between the thoracic pressure and the intraventricular pressure. It was considered positive whenever the ventricular pressure exceeded the thoracic pressure as is the case during systole, and negative when it was less than the thoracic pressure. During diastole the difference between these pressures are always small (±10 mm Hg or less). In the normal untraumatized animal it is zero or positive (filling by venous pressure). After the animal deteriorates from repeated experiments it may become negative, (filling by an action of the ventricular wall or suction). This suction is greater as a result of conditions which interfere with venous return and diminish the size of the ventricles by x-ray (mitral stenosis or bleeding). The force of suction is lessened after transfusions which increase the size of the ventricles. Considerations are advanced for believing that the suction force originates in elastic recoil of the ventricular wall and that it is not clearly an important factor in the mechanism of cardiac pumping.
Propagation of impulses through the atrioventricular node
Authors: Alanís Jesús , López Enrique , Mandoki Juan J. , Pilar Guillermo
Published: December 2017

Records taken from the bundle of His and A-V node region of isolated and perfused dogs' hearts showed an action potential (N potential), which appeared after the auricular response and preceding the electrogram of the bundle of His (H potential). The H potential may disappear without affecting the N potential and the latter may be abolished while the auricular electrogram is still present. These observations permit the interpretation that the N potential is generated independently. The temporal course and the time of occurrence of the N potential, indicate that it represents the activity of the A-V node. The N potential divides the A-H interval into A-N and N-H latencies. Progressively increasing frequencies of activation of the auricle lengthened first the N-H latency until the H potential disappeared. Higher frequencies lengthened the A-N latency until the N potential also disappeared. In order to explain the experimental findings, it is suggested that there are two functional discontinuities, one located between the A-V node and the bundle of His, and the other between the atrium and the A-V node; the first is the most vulnerable for propagation.
Cerebral venous outflow in the dog; influence of adrenergic and cholinergic substances
Authors: McClure Claude , Green Harold D.
Published: December 2017

In the intact dog, jugular vein outflow markedly decreased during adrenergic stimulation. After occlusion of both jugular bulbs and both vertebral venous sinuses with celloidin and ligation of all collateral communications along the jugular veins, in the orbit and underlying masseter muscle, lateral sinus outflow was not appreciably influenced by intra-arterial injections of 50 µg of epinephrine or arterenol, or by stimulation of the headward end of the severed vasosympathetic trunk, but intra-arterial injections of methacholine caused a weak vasodilator response. It was concluded that, in the dog, prominent communications exist between intra- and extracranial venous structures. Apparent vasoconstrictor responses are due to a reduced contribution to the jugular bulb from extracranial structures and/or to a deflection of some of the cerebral venous blood into channels other than the jugular bulb, as a result of vasoconstriction in the extracranial beds. Vasoconstrictor and cerebral metabolic effects reported in man, using the nitrous oxide technique, might be due similarly to varying contamination of the internal jugular vein blood by blood draining from adrenergically reactive facial vascular beds.
Release of 5-hydroxytryptamine and adenosinetriphosphate in extracorporeal circulatory systems as a result of corpuscular blood trauma
Authors: Sarajas H. S. S. , Kristoffersson R. , Frick M. H.
Published: December 2017

Model experiments in rabbits and dogs with a simple extracorporeal circuit yielded suggestive evidence that 5-hydroxytryptamine (5-HT, serotonin) and adenosinetriphosphate (ATP) are released into plasma as a result of corpuscular blood trauma. Concurrently the urinary excretion of 5-HT was markedly increased, while that of 5-hydroxyindoleacetic acid (5-HIAA), the main excretory product of 5-HT, showed the opposite trend. In view of the potent vasoactive, cardiopulmonary and allied effects of ATP and 5-HT the findings are applicable as explanations for some features associated with perfusion experiments in general. They may also serve as a guide for disentangling the mechanisms of some complications including the fatalities following the use of heart-lung machines for open cardiac surgery.
Changes in inorganic composition of tissues in experimental osteolathyrism
Authors: Borle A. B. , Karnovsky M. J. , Nichols G.
Published: December 2017

This report presents data on changes in the electrolyte content of plasma, epiphyseal cartilage, bone and muscle of weanling rats suffering from acute osteolathyrism. There was no change in the plasma pH, the hematocrit, and the plasma concentration of water, Cl, Na, K and P. However, an 11% decrease in Ca was found. In cartilage, the water content increased 16%. On a wet weight basis, Ca decreased 24%, P 16%, and K 19%, while Cl increased 11% and Na did not change. In bone, the only significant change was a 6.5% increase in water, its concentrations of Ca and P remaining at the control levels. No changes were found in muscle. Histochemical reactions for acid mucopolysaccharides, such as changes in metachromasia, indicated that the cartilage matrix is undergoing substantial modifications in osteolathyrism. It is suggested that a defect in sulfur metabolism produces an anionic deficit in cartilage which is met by decreased Ca++ and increased Cl– concentrations, thereby increasing the number of osmotically active particles and secondarily influencing the water content.
Effect of ether anesthesia on 17-hydroxycorticosteroid secretion in dogs
Authors: Suzuki Tatuzi , Yamashita Kazukuni , Mitamura Takaaki
Published: December 2017

In dogs with previously cut dorsal spinal roots (T11-L3), adrenal venous blood was collected without anesthetic or pain. Ether was then inhaled for 30–60 minutes. During and after ether inhalation, adrenal venous blood was again collected and the plasma was analyzed for 17-hydroxycorticosteroids (17-OHCS). The mean preinhalation control secretion rate of 17-OHCS by one adrenal was 0.10 (0.06–0.20) µg/kg/min. During ether inhalation it increased to 0.34–1.2 µg/kg/min. Thirty to sixty minutes after the end of ether inhalation the secretion rate increased to a maximum of 0.79–1.8 µg/kg/min. and then decreased.
Effects of foreign bodies in cloaca and rectum of the chicken on feed consumption
Authors: Sturkie Paul D. , Joiner W. P.
Published: December 2017

Small plastic buttons were sutured in place in the rectum, urodeum and other sites in the cloaca of White Leghorn hens and the effects upon feed consumption were determined. When the foreign body was placed in the rectum there was a marked decrease in feed consumption, which returned to normal after removal of the object. Mechanical stimulation by the foreign bodies in other areas of the cloaca was without effect.
Factors controlling B12 uptake by intestinal sacs in vitro
Authors: Strauss Elliott W. , Wilson T. Hastings
Published: December 2017

Sacs of everted small intestine were incubated in bicarbonate-saline containing radioactive vitamin B12 with or without a source of gastric intrinsic factor (IF). In both the hamster and guinea pig the lowest ileum was most active in B12 uptake in the presence of intrinsic factor, the upper jejunum showing little or no uptake. Low temperature and anaerobic conditions completely abolished the stimulatory effect of IF on B12 uptake. Intrinsic factor did not bind to the intestinal wall in the absence of B12 (even in the presence of calcium ion) as the IF activity could be completely removed by gentle washing of the tissue. The vitamin and intrinsic factor must be present together to cause intestinal uptake of B12.