bluuebunny/crossref_metadata_2025 huggingface dataset:
Potassium Exchange in Atrial Fibrillation
Authors: Holland W. C.
Published: December 2017

Atrial fibrillation has been produced in isolated rabbit auricles suspended in medium of low K by stimulating (600–1200 /min.) in the presence of acetylcholine (3.0 x 10–4 gm/ml). The effects of acetylcholine, quinidine and stimulus frequency on the rate of loss of K by the auricle were investigated in an attempt to see if changes in permeability occurred with the onset of fibrillation. The thesis is developed that fibrillation begins at a time in the myocardium when the rate of outward flux of K, and possibly the inward flux of Na, exceeds a certain critical value (8.0–10.0 mm/kg tissue/5 min.). It is suggested that when this critical flux is exceeded, ectopic pacemakers (single or multiple) appear in the myocardial membrane, the maintenance of which requires the presence of acetylcholine in sufficient concentrations.
Phospholipid Antithromboplastin
Authors: Silver M. J. , Turner D. L. , Tocantins L. M.
Published: December 2017

The anticoagulant activity of brain phosphatide fractions may be assayed using sodium desoxycholate which produces water clear preparations instead of emulsions. The purified phosphatide fractions studied are neither toxic, nor pyrogenic and produce an elevated and lasting increase in the clotting time of blood, when administered intravenously to dogs.
Characterization of the Acute Pulmonary Edema That Follows Vagal Section in the Guinea Pig
Authors: Schmitt G. Henry , Meyers Frederick H.
Published: December 2017

Cervical vagal section is rapidly fatal to the guinea pig. The process is one of pulmonary hyperemia followed usually but not necessarily by transudation. Factors incidental to laryngeal paralysis or to tracheotomy are not implicated nor are the changes agonal. The changes must be due to afferent denervation since atropine does not induce or intensify the changes. Sympathetic hyperactivity is not involved; on the contrary, prior reduction of sympathetic tone intensifies or induces the change. Isopropylarterenol, a smooth muscle relaxant, prevents the effects of vagal section. The pulmonary changes following vagal section are, therefore, due to a loss of the sympathetic tone necessary to maintain normal smooth muscle tone in the bronchioles or pulmonary vessels. Since the loss of sympathetic activity results from section of sensory fibers in the vagus, it is reflex in origin.
Effects of Epinephrine on Carbohydrate Metabolism in Underfed and ad Libitum-Fed Rats
Authors: Spirtos B. N. , Stuelke R. G. , Halmi N. S.
Published: December 2017

Rats fed 10 gm of a commercial diet for 4–5 weeks and fasted for 24 hours showed less rise in liver glycogen and blood sugar levels in response to the injection of epinephrine than did ad libitum-fed-fasted rats. Gastrocnemius glycogen levels were found to be higher in underfed-fasted animals and fell to the same extent as in ad libitum fed-fasted animals when epinephrine was given. Blood lactate concentrations, however, rose less markedly in the underfed-fasted group. This may have been at least partly responsible for the diminished rise in hepatic glycogen and blood sugar.
Effects of Gastroenterostomy and of Pyrogen on Mann-Williamson Ulcer
Authors: Necheles H. , Gordon M. R. , Gaspar H. , Walker L.
Published: December 2017

Dogs were subjected to the Mann-Williamson operation. Twenty-two controls had a mean survival rate of 95 days, and all had gastric or jejunal ulcers. In 12 dogs with the Mann-Williamson operation and simultaneous gastroenterostomy, the mean survival rate was 56 days, and gastric or jejunal ulcers were found in all. Fourteen dogs with the Mann-Williamson operation, treated with Piromen, had a mean survival time of 117 days, and ulcers were found in most animals. The questions of the jet theory of ulcer formation, nutritional deficiency, and suture line ulcer in the Mann-Williamson preparation are discussed.
Adrenal Cortical Activity in Scorbutic Monkeys and Guinea Pigs
Authors: Banerjee Sachchidananda , Singh Haobam Devendra
Published: December 2017

Twenty-four-hour urinary excretions of 17-ketosteroids were determined in female guinea pigs and rhesus monkeys during the progress of scurvy. Urinary excretions of both corticosteroids and 17-ketosteroids were also determined in female guinea pigs during the progress of scurvy and in pair-fed normal controls. 17-Ketosteroid excretion diminished in both guinea pigs and monkeys during the early stages of their depletion of ascorbic acid. The excretion of this steroid, however, increased tremendously in all the 3 monkeys and in 7 of 10 guinea pigs, just before the animals died of severe scurvy. In three guinea pigs, the excretion was considerably diminished when they became acutely scorbutic. The excretion of both corticosteroids and 17-ketosteroids increased to a considerable extent in four of five guinea pigs when they became severely scorbutic but in the remaining guinea pig both these excretions diminished when the animal became severely scorbutic. Inanition had little effect on the urinary excretions of these steroids. It is concluded that the levels of steroids of cortical origin in urine may not have any relation to the vitamin C nutrition of the body. Different degrees of stress produced in these animals due to vitamin C deficiency might be responsible for the variation in the excretions of these steroids.
Protein-Bound Sterols in Rodent Urine
Authors: Finlayson J. S. , Baumann C. A.
Published: December 2017

Normal rats excreted an average of about 15 µg of cholesterol in the urine daily plus 2 µg of a fast-acting sterol; mice, 2 µg and 0.2 µg, respectively. Chromogenic, chromatographic and chemical evidence suggested the fast-acting sterol to be Δ7-cholestenol. The sterols of rat urine were bound to both albumin and globulin, cholesterol being more concentrated in the globulin fraction. The excretion of cholesterol varied with age, sex, species, and strain; it could be increased greatly by injecting Δ7-cholestenol, somewhat by injecting cholesterol or by feeding a high fat diet, and very slightly by feeding a high protein diet; it was not altered by high dietary cholesterol, by glomerulonephritis due to N,N'-diacetylbenzidine, nor by the presence of a hepatoma. The urinary cholesterol of the rat was 74% unesterified; the fast-acting sterol, 24%. Six to eleven per cent of the total sterol of rat and mouse bladder was found to be fast-acting, all bladder sterol being unesterified.
Localization of Spontaneous Respiratory Neuronal Activities in the Medulla Oblongata of the Cat: A New Location of the Expiratory Center
Authors: Haber Edgar , Kohn Kurt W. , Ngai S. H. , Holaday D. A. , Wang S. C.
Published: December 2017

Medulla oblongata of 80 vagotomized cats was explored with microelectrodes. Spontaneous respiratory neuronal activities and chest movements were recorded simultaneously with a twin beam cathode ray oscilloscope. It was found that inspiratory discharges are concentrated in the reticular formation between 3 mm rostral and 1 mm caudal to the level of the obex, which corresponds approximately to the inspiratory region of Pitts, Magoun and Ranson. On the other hand, expiratory discharges are not obtained in Pitts' expiratory area, but are found in a circumscribed region in the reticular formation from the level of the obex to 3 mm caudally. Electric stimulation of this region has been found recently by Ngai and Wang to yield marked expiratory spasm. It is concluded that the expiratory center is located caudally to the inspiratory center in the cat. The spontaneous respiratory neuronal discharges continue with no alterations of pattern of firing during drug-induced respiratory paralysis, and are increased both in number and in frequency during CO2 inhalation. Stimulation of the vagus nerve with 50 shocks/sec. reduces inspiratory discharges and prolongs the duration of expiratory discharges.
Excitation and Conduction in Immature Nerve Fibers of the Developing Chick
Authors: Carpenter F. G. , Bergland R. M.
Published: December 2017

The velocity of impulse transmission in sciatic nerves dissected from fetal chicks has been measured at various stages of development. From day 10 through the adult stage an 80-fold increase in conduction velocity has been observed. The linear velocities of the fastest components are 0.5 m/sec. at day 10, 7–11 m/sec. at day 21, and 50 m/sec. in the adult. In immature nerve prior to myelination ( day 10) at least two components of different velocities may be recognized. Spike potentials at day 16 are almost identical in form to the A complex of the adult although the rate of propagation is slower. Potential changes that are believed to be associated with transmission in C fibers are visible at day 16. During development the increase in conduction velocity which was observed was concomitant with the deposition of myelin and when the velocity was increasing most rapidly, the process of myelination was found to be most active. A linear relationship between fiber diameter and CV has been observed only in the juvenile and adult forms. Microscopically the nerve fibers appear to be unmyelinated at day 10-day 14 and at the time of hatching myelination is rather extensive. Before day 15 it was impossible to make a diameter/velocity correlation since measurements with the light microscope are inaccurate below 1µ.
Inhibitory Effect of Pancreatic Secretin on Gastric Secretion
Authors: Greenlee Herbert B. , Longhi Enrique H. , Guerrero Jose Delgadillo , Nelsen Thomas S. , El-Bedri Abdul Latif , Dragstedt Lester R.
Published: December 2017

In dogs prepared with both a vagus denervated Heidenhain pouch and a total pancreatic fistula, the intravenous injection of pancreatic secretin (Lilly) produced a profuse secretion of pancreatic juice and a simultaneous marked inhibition of gastric secretion. In dogs prepared with an isolated antrum pouch and a Heidenhain pouch the gastric secretion induced by the instillation of food in the antrum pouch was completely inhibited by the intravenous injection of pancreatic secretin. On the other hand, the intravenous injection of pancreatic secretin had little or no effect on the secretion of gastric juice produced by insulin hypoglycemia or by the injection of histamine. It is suggested that pancreatic secretin may represent the mechanism by means of which acid food in the duodenum inhibits gastric secretion. It is probable that this inhibition is caused by prevention of gastrin release from the antrum rather than to a depressant effect on the parietal cells.
A Possible Mechanism of Action of Quinidine
Authors: Holland W. C.
Published: December 2017

Quinidine increases the refractory period and depresses both the rate and amplitude of beat of isolated rabbit atria. These effects can be enhanced by elevating the K content of the medium twofold and completely blocked by lowering the K to one-sixteenth the normal amount. Small amounts of acetylcholine act in a manner similar to low K. These observations suggest that quinidine produces its effects by depressing outward flux of K ions. Ion transport studies revealed this to be the case. The hypotheses that quinidine in final analysis acts by blocking the intracellularly released acetylcholine is presented and discussed.
Microscopic Observations on the Action of Histamine on Small Blood Vessels
Authors: Lee J. S.
Published: December 2017

Studies have been made by microscopic observation of blood vessels in skin, skeletal muscle, mesentery and intestinal wall. In cats anesthetized with pentobarbital sodium, the effects of histamine upon the diameters of small blood vessels have been observed and it has been found that, in general, larger microscopic vessels respond to topically and intravenously applied histamine by constriction, whereas smaller venules and arterioles, in general, respond by dilation. After blood vessels have been constricted by continuous infusions of epinephrine or sympathetic stimulation, the administration of histamine induces a dilation. Mesenteric and intestinal small veins are more sensitive to histamine than are small arterioles in the same structures.
Demonstration of ‘Abolition of Action Potentials’ and ‘Subthreshold Responses’ in the Cobalt Electrode System
Authors: Tasaki Ichiji
Published: December 2017

In a model of the nerve membrane consisting of a cobalt wire immersed in a solution of HCl and CrO3, ‘abolition of action potentials,’ ‘subthreshold responses’ and the ‘impedance loss during activity’ have been demonstrated. These observations are considered to support the ‘two-stable state hypothesis’ of nerve excitation.
Muscular Heat Production in Pigeons During Exposure to Cold
Authors: Steen J. , Enger P. S.
Published: December 2017

Pigeons were kept at different air temperatures while measurements were taken of the temperatures in various parts of their bodies. At room temperature the abdomen and the pectoral muscles had nearly the same temperature. At –22°C the pectorals stayed one-half to two degrees warmer than the abdomen, which remained the same as at room temperature. Myograms from the pectorals showed a considerable electrical activity in the cold which vanished at room temperature. It is concluded that the increased pectoral temperature reflects an elevated heat production. As the pectorals of a pigeon make up about one-third of the body weight, it is clear that they make a significant contribution to the accessory heat during cold stress.
Effect of Alimentary Lipemia on the Turnover of Plasma Phosphatides in the Dog
Authors: McCandless Esther L. , Zilversmit D. B.
Published: December 2017

Lymph P32-labeled phospholipides are removed from the blood only slightly more rapidly than plasma phospholipides. The observation that lymph and plasma phospholipides exchange rapidly when mixed in vitro may explain this similarity. The amount of phospholipide which is contributed to plasma by lymph during alimentary lipemia entirely explains the 15–30% increase in plasma phosphatide concentration in fat-fed dogs. Alimentary lipemia in dogs does not appear to increase the disappearance of injected labeled plasma phosphatides from the blood or the synthesis of hepatic and intestinal phospholipides. Thus, no evidence was obtained for an increase in the turnover of plasma phosphatides during transport of dietary fat in the bloodstream.
Changes in Lipid Composition of Lymph During Cholesterol Absorption in the Rat
Authors: Vahouny George V. , Treadwell C. R.
Published: December 2017

Time studies of the appearance of lipid fractions in the thoracic duct lymph of rats were performed following the administration of emulsions containing cholesterol, oleic acid and sodium taurocholate. The influence of added protein on lipid levels and the total nitrogen of lymph was also studied. Addition of albumin to administered saline was without effect on lymph flow, lipid fractions or total nitrogen. In those animals receiving cholesterol, oleic acid and taurocholate, in addition to albumin, a rapid increase in total lipid was evident during the initial 3 hours, followed by a gradual fall in this fraction to near preabsorptive levels at the end of 9 hours. Comparable changes were observed in the ester cholesterol, neutral fat and phospholipid fractions. Animals receiving a similar emulsion lacking albumin displayed less marked increases in the lipid fractions which were, however, prolonged throughout the experimental period. In contrast to the other lipid fractions in this group, the amount of lymph cholesterol for the 24-hour period was significantly greater than in the comparable group receiving albumin. During cholesterol absorption in both experimental groups, the increase in total lymph cholesterol was attributable almost entirely to an increase in the esterified fraction, which comprised between 84 to 92% of the absorbed sterol.
Differential Action of Chlorpromazine on Reflexes Conditioned to Central and Peripheral Stimulation
Authors: Rutledge L. T. , Doty R. W.
Published: December 2017

Cats chronically prepared with implanted electrodes are trained to respond with a foot flexion equally well to electrical stimulation of the cerebral cortex and to tonal or photic (peripheral) stimuli. Under appropriate doses of chlorpromazine a greater depression of peripherally induced flexions as compared with those cortically elicited is observed in most animals. At an average of 7 mg/kg the depression is complete to peripheral stimuli whereas cortical stimulation can elicit a moderate number of flexions. This differential action is not obtained with LSD-25, morphine sulfate, or pentobarbital sodium. Reserpine results are inconclusive but indicate some similarity to chlorpromazine. Drug effects on afferent systems are discussed.
Relationship Between Concentrations of Albumin and Lipids in Plasma of Experimentally Nephrotic Rats
Authors: Rosenman Ray H. , Smith Malcolm K.
Published: December 2017

Correlative studies were made of the concentrations of albumin and lipids in the plasma of rats made nephrotic by injection of antikidney serum. It was found that the increased concentrations of plasma triglycerides, cholesterol and phospholipid in such rats were inversely correlated with the magnitude of their lowered plasma albumin content, rather than with the amount of antikidney serum that was injected. The results are consistent with the belief that a causal relationship exists between the deficiency of albumin and the increased lipid content of nephrotic plasma.
Question of an Inhibitory Hormone From the Gastric Antrum
Authors: Longhi Enrique H. , Greenlee Herbert B. , Bravo Jose L. , Guerrero Jose Delgadillo , Dragstedt Lester R.
Published: December 2017

Acid applied to the antrum mucosa in dogs inhibits the gastric phase of gastric secretion as exhibited in the vagus denervated Heidenhain pouch. To determine if this inhibition of secretion is due to failure of formation or release of gastrin from the antrum, or to the liberation of an inhibitory hormone from the gastric antrum which acts on the parietal cells, dogs were prepared with an isolated Heidenhain pouch and two pouches prepared from the gastric antrum. These antrum pouches were prepared with vagus innervation intact and with vagus innervation eliminated. Gastric secretion in the Heidenhain pouch elicited by the introduction of liver solution or acetylcholine into one of the antrum pouches was not inhibited by the introduction of acid into the second antrum pouch. These data suggest that acid in contact with the antrum mucosa prevents the formation or release of gastrin and does not release an inhibitory hormone.
Absorption of Lipid and Cholate From Ileal Loops in Unanesthetized Dogs
Authors: Annegers John H.
Published: December 2017

Oleic acid or triolein, alone or with adjuncts, was introduced every 15 minutes for 3 or 6 hours into the upper end of 24-inch Thiry-Vella ileal loops. The lower fistula drained freely throughout, and after flushing the loops, the amount of lipid which disappeared from the test mixture was determined. The initial concentration of lipid in the test mixture was varied by adding solutions of 0.9% NaCl, 1.0–3.0% NaHCO3, or 0.4–6% desiccated ox bile. The rate of lipid absorption when oleic acid was given varied directly with the initial lipid concentration and inversely with increases in the volume of the test mixture traversing the loop. Since bile salt solutions stimulated loop secretion, lipid absorption rate at given initial oleic acid concentrations decreased. 1.3–2.5% desiccated ox bile, but not higher or lower concentrations, increased the rate of lipid absorption when the initial lipid concentration and the change in volume of test mixture during loop passage were under statistical control. When atropine was given or when NaHCO3 was added to oleic acid, the volume of test material decreased during loop passage and the rate of lipid absorption at given initial oleic acid concentrations increased. The average rate of absorption of undiluted oleic acid in atropinized dogs was 7840 mg/hr. The rate of lipid absorption when triolein was given also increased with the initial triolein concentration, and was augmented further by the administration of atropine. Undiluted triolein in atropinized dogs was absorbed at the average rate of 1690 mg/hr. The rate of cholate absorption increased with the concentration of cholate in the test solution. Oleic acid reduced cholate absorption rate.
Effect of Ingestion of Various Lipids Upon Intestinal Absorption of Phospholipid
Authors: Byers Sanford O. , Friedman Meyer
Published: December 2017

The phospholipid content of intestinal lymph of rats was analyzed after ingestion of triglyceride, cholesterol, cholate and a mixture of phospholipids. The administration of the triglyceride and cholate led to an increased intestinal absorption of phospholipid. The ingestion of excess cholesterol or phospholipids, however, appeared ineffective in this particular regard.
Intestinal Permeability to Proteins in the Newborn Herbivore
Authors: Deutsch H. F. , Smith Vearl R.
Published: December 2017

The permeability of the gut of the newborn herbivore to the protein molecules of milk whey is largely lost within 24 hours following birth. All of the colostrum whey proteins, not only the antibody fraction, are absorbed during this stage of intestinal permeability. The nonantibody proteins are molecules of relatively low molecular weight. These are rapidly lost through the kidney, the antibodies being largely retained. Crystalline ß-lactoglobulin may be prepared from urine during the proteinuric stage which is very pronounced during the first 24 hours of postpartum life in calves that have had ready access to milk. Unsuccessful attempts were made to maintain the intestinal permeability beyond the first 24 hours of postpartum life. Hormonal and milk factors did not appear to be responsible for the discussed change. Transfusing with the blood of the mother and other biological agents were also ineffective.
Absorption Force of the Capillaries of the Visceral Pleura in Determination of the Intrapleural Pressure
Authors: Agostoni E. , Taglietti A. , Setnikar I.
Published: December 2017

A method is described for the measurement of the net absorption pressure of the capillaries at the level of the visceral pleura. This pressure was found to be about 15 mm Hg and due to the difference between the plasma colloid osmotic pressure and the hydrostatic pressure in the pulmonary capillaries; such a difference does not exist in the parietal pleura. The hydrostatic pressure of the pulmonary capillaries estimated by this method has the same value as that observed by cardiac catheterization. From the results and theoretical considerations it appears that the negative intrapleural pressure is the result of the net absorption pressure of the visceral pleura. This force is higher than the elastic retraction force of the lung and therefore it holds the visceral and the parietal pleura together.
Factors Affecting Blood Volumes in Hypophysectomized Female Rats
Authors: Bond Charles F. , Leonard Samuel L.
Published: December 2017

Plasma volume by the dye (T-1824) method, hematocrit, hemoglobin concentration and plasma specific gravity were determined, and from them total blood and erythrocyte volumes and plasma protein concentration were derived in hypophysectomized female rats fed standard and enriched diets. The effects of insulin, growth hormone and prolactin were also studied. Hypophysectomy decreased the plasma volume and established a lower, stable plasma volume/body weight ratio which was not influenced significantly by diet or hormones. The erythrocyte volume/body weight ratio markedly reduced after hypophysectomy, was readily increased by the enriched diet, especially in younger animals. Insulin injections did not alter the blood picture or increase the body weight. Growth hormone increased both plasma and erythrocyte volumes proportionally to the elevation in body weight and also increased the total plasma protein. Prolactin, possibly contaminated with growth hormone as noted by the tibia test, acted similarly to growth hormone but to a lesser extent.
Orientation of Circulating Human Estrogens by Albumin
Authors: Bischoff Fritz , Stauffer Royce D.
Published: December 2017

Bioassays of last trimester human serum fractions, separated by the scheme of Veldhuis, indicate that the conjugated estrogen fraction (estrone sulfate, estriol glucuronide, etc.) contributes about one-fourth, free estrone less than one-twentieth, free estriol one-fifth, and free estradiol one-half of the total biologic activity. No protein conjugated estrogen was found on alkaline hydrolysis. By dialyzing between human serum and human albumin, it was shown that estriol and estradiol added to normal serum and the endogenous estrogens of last trimester serum migrate from serum to albumin at a rate and amount comparable to the migration from albumin to albumin. Since the data gave no indication of competition of the other serum constituents (globulins, lipoproteins, etc.) with albumin, it is concluded that albumin is the most important element in regulating the transport of estrogens in serum.
Hepatic Glycogen, Lipogenesis and Glucose-6-Phosphatase in X-Irradiated and Control Rats
Authors: Coniglio John G. , Kirschman John C. , Hudson Granville W.
Published: December 2017

Incorporation of C14-acetate into hepatic fatty acids increased in irradiated, fasted rats (750 r total-body x-irradiation) compared to fasted controls as early as 6 hours postirradiation. At this time hepatic glycogen in irradiated animals was lower than in controls and lower than in irradiated animals at 30 minutes postirradiation. Incorporation remained constant at 12 hours postirradiation but glycogen concentration in irradiated rats was increased over controls. At 18 hours the irradiated rat exhibited both increased hepatic glycogen and increased lipogenesis. The increase in liver glycogen in irradiated, fasted rats could be prevented effectively by administration of S,ß aminoethylisothiouronium bromide 10 minutes prior to irradiation. In those irradiated rats in which symptoms of toxicity of the drug were not severe, enhancement of hepatic lipogenesis either was not prevented or was only partly prevented. The results are consistent with the hypothesis that liver glycogen is not the sole factor contributing to increased hepatic lipogenesis in irradiated fasted rats. Assay for hepatic glucose-6-phosphatase at 0.5, 24 and 48 hours after 750 or 1000 r total-body x-irradiation revealed no significant change due to the irradiation. However, both concentration and total activity of the enzyme were increased by fasting.
Effects of Exposure of Obese Rats to Simulated High Altitudes
Authors: Altland Paul D. , Mickelsen Olaf , Highman Benjamin
Published: December 2017

Osborne-Mendel rats became obese when fed a high fat diet for 6–15 months. Obese rats and stock-fed rats were exposed 6 1/2 hours a day, 5 days a week to 18,000 or 25,000 feet simulated altitude for from 4 to 6 months. Both groups of rats developed the same degree of polycythemia and had the same mortality rate. The obese rats lost more weight from altitude exposure and also showed a slightly higher incidence of cardiovalvular thickening and cardiac vegetations, particularly among those that died. The mean heart weight of unexposed obese rats was 50% greater than that of stock-fed rats; the heart weights of both groups increased about 70% following 191 days of exposure. In acute altitude tests at 33,500 feet simulated altitude, both Osborne-Mendel and Sprague-Dawley rats on the high-fat diet, irrespective of the degree of obesity, died within 86 minutes. Sixty per cent of the stock-fed rats survived for a longer period. Some of the heaviest Osborne-Mendel rats on the high-fat diet died within 3 minutes at this altitude. Preoxygenation prevented these early deaths, but neither preoxygenation nor a slow rate of ascent (500 ft/min) had any effect on the high mortality of rats on a high-fat diet exposed to altitude.
Effect of Ether and Barbiturate Anesthesia on the Reaction of Rats to Dextran and of Dogs to Polyvinylpyrrolidone
Authors: Hanna C. H. , Marshall L. H.
Published: December 2017

Changes in mean arterial blood pressure and the extravascular appearance of injected dye (T-1824) were followed in rats that received massive intravenous injections of dextran while conscious or while anesthetized with ether or barbiturates. In conscious rats, and during or after ether anesthesia, the usual vasodepression was moderate or absent and the incidence of bluing was high. Rats anesthetized with barbiturates showed severe vasodepression and little bluing. Dogs injected with a small amount of PVP exhibited a significant fall in blood pressure when conscious or when under barbiturate anesthesia, but were partially protected by ether anesthesia. Bluing occurred under all conditions in this species. Change from the supine position to prone or standing did not influence the results. Noradrenaline partially protected rats but increased the severity of the reaction in dogs.
Relative Influence of Variations in Arterial and Venous Pressures on Resistance to Flow
Authors: Levy Matthew N.
Published: December 2017

Arterial inflow and arterial and venous pressures were measured in the hind legs of dogs under conditions of variations in arterial or in venous pressures. When the arteriovenous pressure gradient was reduced by continuous or stepwise diminutions of arterial pressure, a curvilinear relationship, convex to the pressure axis, was observed when flow was plotted as a function of pressure gradient. With elevations of venous pressure, on the other hand, the pressure-flow curves were invariably linear over the range studied, and the extrapolated curve usually intersected the flow-axis at a low, positive value. The calculated value of resistance fluctuated markedly with variations in arterial pressure, but usually decreased only slightly with elevations of the venous pressure.
Effects in Dogs of Decrease in Glomerular Filtration Rate on Cation Excretion During Intravenous Administration of Unreabsorbable Anions
Authors: Lauson Henry D. , Thompson David D.
Published: December 2017

Glomerular filtration rate (GFR) was reduced in stages (by inflation of a balloon located in the aorta above the renal arteries) during administration of the Na salts of the ‘unreabsorbable’ anions, p-aminohippurate or thiosulfate. The large excretion of anions obligated equivalent excretion of cations. The fraction of excreted anions neutralized by Na ions decreased as GFR was reduced; the fraction neutralized by K, NH4 and H ions increased correspondingly. The ‘availability’ of these three cations was apparently limited so that, at any given level of GFR, the larger the total anion excretion the smaller was the fraction neutralized by these cations. Substitution of K, NH4 and H for Na was presumably accomplished by ion exchange mechanisms. Net ‘secretion’ of K was demonstrated with increasing frequency as GFR was reduced below 60% of control. Absolute excretions of K, NH4 and H ions remained within control ranges until GFR decreased below about 50% of control. Absolute excretion of Na, however, decreased sharply with decrease in GFR. It is concluded that acute reduction of GFR, by itself, results in a more complete absorption of filtered sodium; if in this circumstance unreabsorbed anions in tubular fluid obligate cation excretion a considerable proportion of the cations, as K, NH4 and H ions, are provided by the tubule cells in exchange for some of the reabsorbed Na ions.
Distribution of Intracarotidly Injected Serotonin in the Brain
Authors: Costa E. , Aprison M. H.
Published: December 2017

Cross circulation experiments, according to the technique of Heymans and Heymans and Swiss and Maison, have been used to study the distribution of serotonin (2–4 mg) injected in the internal carotid artery of the recipient rabbit. Approximately 1% of the injected neurohormone has been recovered from different parts of brain while more than 50% of the injected serotonin is present in the venous jugular blood of the recipient. Some of the injected serotonin reaches the general circulation probably through the sinus vertebralis longitudinalis causing hypotension. Pretreatment with Marsilid does not change the rate of serotonin entrance in nervous tissues although the increase of serotonin content in brain of animals treated with Marsilid is confirmed.
Transmission and Facilitation at the Ephapse Formed by Severed Mammalian Nerves
Authors: Terzuolo C. A. , Eliasson S.
Published: December 2017

The locus of the ephapse formed by severed sciatic nerve of cats has been determined and the mechanism involved in the process of the transmission across the ephapse have been examined. An increased excitability to a cathodal stimulus of the fibers at the ephaptic locus has been demonstrated resulting from subthreshold depolarization related to injury. Transmission and facilitation are likely due to a further depolarizing action exerted either by subliminal electrical stimulation or by neighboring activity, i.e. the negative phase of the triphasic potential of the fibers conducting toward the cut end of the nerve in a volume conductor.
Differential Susceptibility of Afferent Pathways to Anesthetic Agents in the Cat
Authors: Randt Clark T. , Collins William F. , Davis Hamilton S. , Dillon William H.
Published: December 2017

The effects of nitrous oxide, ethylene and cyclopropane on somatic afferent evoked potentials in the posteroventral lateral nucleus of the thalamus, the peri-aqueductal reticular formation of the midbrain, the deep pretectal region of the midbrain, and the caudal paramedian reticular nucleus of the medulla oblongata were studied in 46 cats immobilized with muscle relaxants. The time of onset to maximal effect, percentage decrease in amplitude of the evoked subcortical potentials and the duration of depression incident to the administration of these anesthetic gases in doses approximating those in clinical use, showed quantitative correlation with the clinically observed potency of nitrous oxide, ethylene and cyclopropane in that order. The anesthetic agents were shown to act differentially on four somatic afferent systems of diverse fiber size and characteristics of transmission suggesting that the anesthetic effect may be determined by factors in addition to the numerical preponderance of synapses in multineuronal systems. The evidence presented suggests more specific susceptibility of small fiber systems to the action of anesthetic agents.
A Method for Assaying Small Amounts of Antidiuretic Substances With Notes on Some Properties of Vasopressin
Authors: Dettelbach Harold R.
Published: December 2017

An intravenous method of high precision for bioassay of antidiuretic substances at low concentrations is described. Sensitivity is high and occurrence of nonspecific antidiuresis is largely avoided. It uses the rat, maintained under constant water load and ethanol anesthesia. Antidiuretic activity of commercial vasopressin in solution, studied under varying conditions of temperature and pH, withstood short boiling at any pH but was reduced after longer boiling, especially in alkaline solutions. Loss of pressor activity did not parallel that of antidiuretic activity at all pH levels. Vasopressin solutions lyophilized or frozen for long periods lost no antidiuretic activity. There was appreciable loss of activity on standing at room temperature for 72 hours. Plasma samples containing vasopressin may be acidified, boiled and centrifuged while the antidiuretic activity remains intact in the supernatant fluid.
Ammonia Excretion of the Guinea Pig and Rabbit
Authors: Richterich R. , Goldstein Leon , Dearborn Earl H.
Published: December 2017

During fasting in guinea pigs a marked drop of ammonia excretion parallel to a drop in titratable alkalinity was observed. Feeding of cabbage increased ammonia excretion in excess of the titratable alkalinity. In acute studies in guinea pigs and rabbits after administration of saline, bicarbonate or hydrochloric acid, a depression of ammonia excretion was consistently observed whenever the urinary pH was close to neutrality, while in acid as well as in alkaline urines an increase in ammonia excretion occurred. When the urine flow was very low (<0.02 ml/min. in the guinea pig or <0.1 ml/ min. in the rabbit) excretion of ammonia appeared to be ‘flow-limited.’ If the ‘critical flow’ were exceeded, ammonia excretion was ‘production-limited.’
Effect of Local Anesthetics on the Isolated Antrum of the Stomach in Dogs
Authors: Woodward Edward R. , Schapiro Herbert
Published: December 2017

Cocaine inhibits the release of gastrin by the pyloric antrum. Dogs were prepared with isolated antrum pouches as well as Heidenhain pouches. Other local anesthetics, Xylocaine, Pontocaine and Nupercaine, were placed in the isolated antrum. The release of gastrin was inhibited to both chemical and mechanical stimuli. Local anesthetic applied to the isolated antrum had no effect on its motility. It is concluded that cocaine inhibits the antrum through its anesthetic rather than its vaso-constrictor property and that this inhibition is not mediated through a motility suppression.
Stimulation of Insulin Output by Monosaccharides and Monosaccharide Derivatives
Authors: Pozza Guido , Galansino Giorgio , Hoffeld Harvey , Foà Piero P.
Published: December 2017

The ability of various sugars and closely related substances to stimulate insulin secretion was studied by means of pancreatic-femoral cross-circulation experiments between hepatectomized donor dogs and normal recipients. In other experiments, the test substance was injected directly into the pancreatic artery of normal dogs. The administration of d-glucose, d-galactose or d-ribose was followed by a prompt hypoglycemia, suggesting insulin secretion; d-arabinose caused an unexplained delayed hypoglycemia, while d-fructose, d-mannose, d-xylose, l-arabinose, 3-methylglucose, d-glucosamine, galacturonic acid and saline had no effect. The tentative hypothesis that insulin secretion is stimulated by sugars which are both utilizable and insulin-sensitive is offered. No relationship between chemical structure and ability to cause insulin release was found.
Comparative Lung-Airway Resistance and Cardiovascular Effects in Dogs and Monkeys Following Parathion and Sarin Intoxication
Authors: Johnson Rudolph P. , Gold Armand J. , Freeman Gustave
Published: December 2017

A comparison in dogs and monkeys of fatal Parathion and Sarin intoxication with regard to respiratory and cardiovascular effects showed that the dog attained relative increases in lung-airway resistance four or more times greater than the monkey. Resistance was higher in the animals having had two ld50's rather than eight. A correlation was found between abundance of peribronchial smooth muscle and severity of resistance. The effects in monkeys support a closer relationship with central or neuromuscular depression, or both, than with rising lung-airway resistance, as in dogs. Both species reacted similarly with regard to intracardiac block and cardiac rates. Monkeys failed to attain a hypertensive state upon cessation of breathing, as did dogs.
Effect of Alternation in Dietary Protein Levels on Pancreatic Enzymes in Rats
Authors: Magee D. F. , White Thomas T.
Published: December 2017

Rats fed diets alternating between high (18%) and low (6%) protein had higher proteolytic enzymes per pancreas than low protein controls and as high totals of these enzymes as high protein controls. The concentration of proteolytic enzymes was higher than either control.
Some Aspects of the Gonadal Regulation of Cholesterol Metabolism
Authors: Fillios Louis C. , Kaplan Ronald , Martin Robert S. , Stare Fredrick J.
Published: December 2017

It was observed that during growth and maturation a sex difference in cholesteremia is revealed following puberty and this difference is associated with the variability of cholesteremia during the female estrous cycle. The highest female levels were found during the follicular phase of the cycle. A radioisotope technique was developed by which it was shown that this elevation is related more closely to an increased endogenous biosynthesis of cholesterol than to a difference in the rate of catabolism.
Renal Response to Nonshocking Hemorrhage: the Role of Intrarenal Shunts
Authors: Goodyer Allan V. N. , Mattie Louis R. , Chetrick Allen
Published: December 2017

In anesthetized dogs, bleeding (1.5–3% of the body weight) was allowed while renal arterial pressure was maintained at constant levels by graded changes of mechanical aortic obstruction. The renal hematocrit decreased, (as measured with I131 albumin and acid hematin, and as compared to the blood hematocrit), primarily as a result of an increased renal plasma volume. These changes are correlated with previously identified alterations of sodium excretion, all independent of renal innervation or arterial blood pressure. It is proposed that hemorrhage may involve an intrarenal redistribution of blood flow favoring diversion of plasma to cell-poor capillaries or to lymphatic spaces.
Dynamics of Epinephrine Distribution in the Dog
Authors: Jones Richard T. , Blake William D.
Published: December 2017

The dynamics of epinephrine distribution have been studied in dogs anesthetized with sodium pentobarbital. Epinephrine concentration in blood plasma samples from various sites of the circulatory system during and after constant intravenous infusions of epinephrine was estimated by a fluorometric method. The arterial epinephrine concentration was observed to reach a stable level after several minutes of infusion, the concentration varying directly with the rate of infusion. The disappearance of epinephrine was rapid and of a first order reaction variety. Various sites of epinephrine removal were detected and include the liver, kidney, gut and hindleg but not the lung. A mathematical model is formulated and proposed as a simple functional relation between the rate of infusion, epinephrine concentration, disappearance constant and the volume of distribution. From the data and this model, it was concluded that the epinephrine was not bound irreversibly to plasma constituents and that it was in ‘equilibrium’ with a volume of fluid greater than the intravascular space.
Significance of the ‘Protein-Sparing’ Effect of Dextrin
Authors: Spivey H. E. , Katayama M. C. , Yoshida M. , Harper A. E.
Published: December 2017

Among the hypotheses proposed to explain the greater food intake and rate of gain of young rats fed ad libitum on low protein diets in which dextrin or corn starch has been substituted for sucrose are: a) increased synthesis of essential amino acids by intestinal microorganisms; b) improved digestion and absorption of protein owing to slower passage of diets containing dextrin through the small intestine; c) reduced destruction of amino acids in the animal body owing to more prolonged absorption of glucose from dextrin. The results of nitrogen balance and feeding experiments indicate that improvement in the efficiency of protein utilization when dextrin is substituted for sucrose is too small for any of the above hypotheses to account for the apparent ‘protein-sparing’ effect of dextrin.
Interactions of Dietary Fiber and Protein on Food Intake and Body Composition of Growing Rats
Authors: Meyer J. H.
Published: December 2017

The addition of cellulose to the diet increases protein needs as measured by gains in the fat-free body of ad libitum and pair-fed growing rats. This was attributed to loss of metabolic fecal nitrogen induced by dietary cellulose addition. It was demonstrated that 30% cellulose addition to the diet caused a need for about 1.85% additional dietary crude casein. Rats fed very low protein rations had a larger portion of their gain as fat because their intake of energy was high in relation to protein intake. This excess energy therefore limited an increase in food intake by which the animal might obtain more protein from these low protein rations. When cellulose replaced the energy portion of the diet (sucrose), food intake increased because the animal no longer needed to dispose of the excess energy as body fat or heat. Therefore, protein in low protein rations influences food intake indirectly through its ratio to available dietary energy.
Placental Transmission and Mammary Gland Secretion of Thyroxin in the Rat
Authors: Hoskins Lansing C. , VanArsdel Paul P. , Willlams Robert H.
Published: December 2017

When large doses of thyroxin are administered to pregnant rats, propylthiouracil goitrogenesis in the fetuses as well as in the mother is prevented. One hour following the intravenous injection of thyroxin-I131 into pregnant rats a small fraction of TCA-precipitable, butanol-extractable radioactivity was recovered from homogenates of their fetuses. Part of this was shown by means of Kieselguhr column chromatography to represent thyroxin. Large amounts of thyroxin administered to lactating rats over a 10-day period failed to prevent propylthiouracil-induced goiter in their suckling offspring. It is concluded that the rat placenta is slightly permeable to thyroxin but the rat mammary gland does not secrete thyroxin in a physiologically active form.
Experimental Epilepsy in Rabbits Development of a Strain Susceptible to Audiogenic Seizures
Authors: Nellhaus Gerhard
Published: December 2017

A group of large, white-furred, blue-eyed rabbits, known as Beverens, was found to be susceptible to audiogenic seizures. Both Beverens and hybrids derived from them have a significantly higher degree of susceptibility to audiogenic seizures than non-Beveren rabbits. No significant difference in susceptibility was observed between Beverens and hybrids, males and females. The peak of seizure susceptibility occurred during the 2nd month of life. A marked increase in the incidence and frequency of seizures was observed in the second and third generation of inbred rabbits. Certain variables influencing seizure-susceptibility are discussed and the advantages afforded by rabbits susceptible to sensory-induced seizures are pointed out.
Effect of Acute Removal of Potassium From the Body on Tissue Electrolytes
Authors: Habib Yehia A. , Nichopoulos George C. , Overman Richard R.
Published: December 2017

Following a 2-hour period of vividialysis against a potassium free fluid, the rate of loss of potassium from the blood of dogs was determined (using K42) as well as the electrolyte and water content of heart, liver and skeletal muscle. A significant increase in potassium content of cardiac muscle and in sodium content of liver was found. There was a definite decrease in the specific activity of muscle potassium as well as in the ratio of muscle to plasma specific activity. The rate of loss of blood potassium (K42 vascular slope) was diminished in animals in which an amount of potassium less than that originally present in the extracellular space was removed. The data exclude the heart, liver and skeletal muscle as the sites from which potassium removed in acute experiments was derived.
Localization of Acidification of Urine, Potassium and Ammonia Secretion and Phosphate Reabsorption in the Nephron of the Dog
Authors: Pitts Robert F. , Gurd Ruth S. , Kessler Richard H. , Hierholzer Klaus
Published: December 2017

The Malvin, Sullivan and Wilde ( The Physiologist 1: 58, 1957) stop flow technique for the localization of tubular function has been applied to a study of potassium and acid excretion in the dog. It has been observed that the urine is acidified in the distal part of the nephron at a site of avid sodium reabsorption. Potassium and ammonia are secreted in the same portion of the tubule. Diamox reduces acidification of the urine and secretion of ammonia and enhances the secretion of potassium. Phosphate is reabsorbed in the proximal part of the nephron in a region which is coextensive with that which secretes p-aminohippurate. All our data are consonant with the view that a mechanism located in the distal part of the nephron exchanges cellular hydrogen and/or potassium ions for sodium ions in the tubular urine. Ammonia diffuses into acid urine and is trapped as ammonium ion. Diamox, by interfering with the supply of cellular hydrogen ions, reduces exchange of hydrogen for sodium and favors the exchange of potassium for sodium.