bluuebunny/crossref_metadata_2025 huggingface dataset:
Lung mechanics in sitting and horizontal postures studied by body plethysmographic methods
Authors: Linderholm Håkan
Published: December 2017

Mechanical properties of the lungs were examined in normal subjects in the sitting and supine body postures using body plethysmographic and conventional methods. At comparable lung volumes airway conductance or resistance (measured independently of esophageal pressure) was quite uninfluenced, and lung conductance or resistance (determined during high-frequency breathing, when esophageal pressure and intrapleural pressure variations are known to agree better than during ordinary breathing) was almost uninfluenced by changes in body posture. A "static" lung compliance estimated from plethysmographically measured lung volumes and the corresponding esophageal pressures was less influenced by posture than the conventionally measured "dynamic" lung compliance. Previously reported differences between lung compliance or resistance in the sitting and supine postures seem to be explained by differences in lung volumes at the measurements and probably also by the variation with posture of differences between intrapleural and esophageal pressure changes during ordinary breathing. Changing from upright to horizontal posture therefore does not seem to alter significantly the true mechanical properties of the lungs.
An assay for gastric intrinsic factor
Authors: Boass Agna , Wilson T. Hastings
Published: December 2017

The stimulation of vitamin B12 uptake by small segments of hamster ileum in the presence of gastric intrinsic factor (IF) has been utilized as a quantitative assay for rat and hamster IF. About 100–150 small segments of everted ileum of the hamster were mixed in a beaker and aliquots of approximately 10 were incubated in flasks containing radioactive B12 with or without IF. Within a certain range of IF concentrations, B12 uptake into the tissue was proportional to the IF added. Of all the tissues studied only gastric mucosa showed IF activity under these conditions. This assay was not only specific for gastric IF, but was also extremely sensitive, giving a positive reaction with a concentration of 0.1 mg gastric mucosa per milliliter of incubating solution.
Effects of infusions of ammonia, amides, and amino acids on excretion of ammonia
Authors: Canessa-Fischer M. , Shalhoub R. , Glabman S. , deHaas J. , Pitts R. F.
Published: December 2017

Ammonium lactate and a variety of amides and amino acids were infused into one renal artery of anesthetized dogs in acidosis. Urine was collected separately from the two kidneys and rates of excretion of ammonia on the two sides were compared. The infusion of ammonium lactate resulted in a prompt increase in ammonia excretion restricted to the side infused. As much as 50% of the infused ammonia appeared as excess ammonia in the urine. The infusion of glutamine, asparagine, alanine, glycine, leucine, and glutamic acid induced bilateral increases in rates of ammonia excretion, commonly greater on the side infused. However, ammonia excretion increased significantly on the side contralateral to that infused. A much smaller fraction of the infused nitrogen appeared as urinary ammonia than when ammonium lactate was infused. The infusion of valine induced no increase in ammonia excretion by either kidney; rather, ammonia excretion was reduced. The significance of these results in relation to the study of renal metabolism of N15 compounds is discussed.
Water uptake in the intact frog
Authors: Pigeon Gilles , Epstein Franklin H.
Published: December 2017

The effects of potassium depletion, calciferol-induced hypercalcemia, hyaluronidase, hypercapnia, and adrenal steroids on the water uptake of intact frogs were studied. The findings suggest that potassium depletion and hypercalcemia interfere with water uptake. Hyaluronidase and adrenal glucocorticoids in doses used were without effect on water transport. Water uptake after oxytocin was greatly decreased by exposing frogs to a high concentration of CO2 in air. The data obtained with frog skin in vivo are discussed in relation to in vitro studies with anuran membranes reported by others.
Actions of vasotocin and some of its analogues on salt and water excretion by the frog
Authors: Jard Serge , Morel Francois
Published: December 2017

The actions of small doses of arginine and lysine-vasotocin on urine flow (V), inulin (CIn), free water (CHH2O), sodium (CNa), and potassium (CK) clearances were studied in Rana esculenta and compared with those of larger doses of oxytocin, lysine-vasopressin, Val3-oxytocin, Ileu8-oxytocin, Phe2-Phe3-Lys8-oxytocin, deamino-oxytocin, and oxypressin. Injections of either arginine or lysine-vasotocin (mean dose .030 µg) induce a small decrease in glomerular filtration rate (GFR) and two marked tubular effects: a) an increase in water reabsorption, CHH2O being reduced even when related to CIn; b) an increase in tubular sodium reabsorption, CNa/CIn being lowered, whereas CK/CIn remains unchanged. Neither oxytocin nor lysine-vasopressin, even in doses 20–25 times higher, promotes the tubular effects typical of vasotocin. Oxytocin promotes a slight decrease in GFR and V. Lysine-vasopressin remains without any effect. All the other artificial analogues of oxytocin injected in large doses increase V, GFR, CNa/CIn and CK/CIn. It is concluded that the vasotocins specifically promote in the kidney tubules of the frog the same two actions described in the other target organs in the amphibians, namely an increase in osmotic permeability to water and a stimulation of active sodium transport.
Iodoantipyrine and Rb86 Cl uptake by brain, cord, and sciatic nerve in the rat
Authors: Mandel Morris J. , Arcidiacono Francesco , Sapirstein Leo A.
Published: December 2017

Rb86 and Iodo131 antipyrine were injected together by vein in rats. The brain, spinal cord, and nerve contents of each label were measured 30 or 60 sec later. Iodoantipyrine values were used to calculate blood flow to these portions of the nervous system. The ratio of Rb86 to iodoantipyrine uptake was used as an index of the efficacy of the hematoneural barrier. The barrier is most complete in the brain, less complete in the spinal cord, and absent in peripheral nerve. Blood flow values per gram are: brain .41 ml/g min; cord .28 ml/g min, and nerve .11 ml/g min. It is suggested that the blood-brain barrier is an anatomical entity rather than a functional one.
Effect of renal papillectomy on ability of the hamster to concentrate urine
Authors: Marshall Sumner , Miller Tracy B. , Farah Alfred E.
Published: December 2017

The effect of surgical removal of the distal portion of the renal papilla was evaluated by subjecting three groups of animals— 1) bilateral papillectomy, 2) unilateral papillectomy with nephrectomy; 3) normal controls—to regimens producing hydration and dehydration. Bilateral sham operations caused no significant effect. The animals were placed in metabolism cages and given carrots alone (hydrating diet), pellets alone (dehydrating diet), and pellets and water ad libitum (normal diet). There were no differences in urine osmolality on carrots alone. During progressive dehydration, the more marked the dehydration the greater the difference in urine osmolality between control and papillectomized animals. On the normal diet, the papillectomized animals consistently excreted twice the volume of a more dilute urine than the controls. Water loads were excreted more rapidly by the papillectomized groups. Simultaneous administration of a 6% oral water load and 100 mU of vasopressin intramuscularly showed that papillectomy reduces the response to an antidiuretic hormone. The results are consistent with the countercurrent hypothesis.
Suppression of rabbit kidney histidine decarboxylase activity by endotoxin
Authors: Schayer Richard W. , Janoff A. , Zweifach B. W.
Published: December 2017

Previous work has shown that bacterial endotoxins activate an inducible form of histidine decarboxylase present in mammalian tissues. The product of this enzyme, induced histamine, has been postulated to have a circulatory function and to oppose the vasoconstrictor actions of the catecholamines on the small blood vessels. The present experiments show that in kidney of endotoxin-treated rabbits there is an anomalous response, histidine decarboxylase being strongly reduced, not activated. The findings are consistent with the view that suppression of induced histamine synthesis, at a time of markedly increased catecholamine release, might potentiate the actions of these vasoconstrictors on the kidney. This event may be a factor in the early endotoxin-induced changes in the glomerular capillaries which prepares them for the subsequent events of the generalized Shwartzman reaction.
Chronotropic response to intravenous infusion in the anesthetized dog
Authors: Ahmad Gulzar , Nicoll Paul A.
Published: December 2017

Ninety-four anesthetized dogs at normal body temperature received 293 intravenous saline infusions by gravity flow through either a femoral or jugular vein. Also nine dogs with body temperature lowered to 27 C received 30 similar infusions. Heart rate and blood pressure were monitored by transducer and oscillographic recording. The chronotropic response of the normothermic group varied with the preinfusion heart rate, with those below 140/min generally showing increases and those above showing no response or a decrease. Negative results with hypothermic animals also having slow preinfusion rates indicate the Bainbridge effect requires the slow preinfusion heart rate to be under vagal inhibition.
Starling's law of the heart. VII: Ventricular function in closed-chest unanesthetized dogs
Authors: Warbasse J. Richard , Braunwald Eugene , Aygen Maurice M.
Published: December 2017

It is generally agreed that Starling's law applies to heart-lung preparations and open-chest, anesthetized dogs. However, there is considerable disagreement about the relevance of the Frank-Starling mechanism to the intact organism. A Kolin-Kado gated, sine wave, electromagnetic flowmeter was placed around the ascending aorta of seven dogs. Changes in left ventricular dimensions were recorded with mercury resistance gauges. Left ventricular diastolic and intrapleural pressures were measured simultaneously. The chest was closed and the dogs permitted to recover from the anesthesia and to breathe spontaneously. Alterations in left ventricular size and effective filling pressure were induced by rapid transfusion or bleeding. Left ventricular stroke work, peak values of aortic blood velocity and acceleration, and left ventricular power all increased as left ventricular size and filling pressures were augmented. At any given filling pressure and ventricular size all these indices of ventricular performance increased during infusion of norepinephrine. These experiments support the view that Starling's law and the ventricular function curve concept are applicable to the heart of the closed-chest, unanesthetized dog with an intact autonomic nervous system.
Changes in feeding behavior after intracerebral injections in the rat
Authors: Wagner J. W. , Groot J. De
Published: December 2017

Changes in basal liquid food intake in sated or fasted rats were measured after localized intracerebral injections (5 µl) of 17 chemical solutions. Lidocaine, pentobarbital, and epinephrine produced feeding in sated or fasted rats with ventromedial hypothalamic (VMH) cannulas; neostigmine, norepinephrine, pentylenetetrazol, and 1.5% NaCl reduced food intake in fasted rats; acetylcholine, histamine, and dextrose had no effect in either state. In sated rats with lateral hypothalamic (LHA) implants, epinephrine, norepinephrine, and 1.5% NaCl produced feeding; lidocaine and neostigmine reduced, whereas norepinephrine augmented food intake in fasted LHA animals. No effect on consumatory behavior was observed after injections into the lateral amygdala. Lidocaine reduced food intake in fasted rats with globus pallidus implants; epinephrine and norepinephrine initiated feeding. Eight other chemicals had no effect on feeding in limited tests. Neostigmine and acetylcholine produced drinking in sated VMH and LHA animals, respectively. These results suggest that closely adjacent neuronal aggregates (VMH-LHA) may have different metabolic requirements for single compounds, and that the VMH functions in satiety mechanisms for food as well as water intake.
Relation between pool size and catabolism of albumin in the mouse
Authors: Friedberg Wallace
Published: December 2017

The catabolism of I131-labeled human serum albumin was investigated in mice in which the total albumin pool was increased with injections of massive amounts of human or mouse albumin. Control mice received the tracer albumin and saline solution. Daily whole-body radioactivity measurements were made on each animal over a period of several albumin half-lives. Since the absolute rate of albumin catabolism (mg/hr) is estimated by the product of the fractional rate (fraction of albumin pool/hr) and the pool size (mg of albumin), an unchanged or increased fractional rate concomitant with an increased pool size indicates a greater absolute rate of catabolism. A small increase in the fractional rate of albumin catabolism, unrelated to an immune response, occurred in the albumin-loaded mice. By inference, the equilibrium level of albumin in the serum is determined, in part, by a variable absolute rate of breakdown and this rate of breakdown is related to the total albumin pool size. Renal and fecal excretion of injected protein was insignificant.
Effects of cold acclimatization on liver di- and triphosphopyridine nucleotide
Authors: Hannon John P. , Rosenthal Arthur
Published: December 2017

The levels of oxidized and reduced di- and triphosphopyridine nucleotide were measured in liver tissue from rats that had been exposed to cold (4 ± 1 C) for 1 month. These animals exhibited about 65% more reduced and total triphosphopyridine nucleotides than control animals maintained at an ambient temperature of 25 ± 1 C. The significance of these alterations to the efficiency of oxidative phosphorylation is discussed.
Secretion and activity of histamine and serotonin during cold adaptation
Authors: Leblanc Jacques
Published: December 2017

The urinary excretion of histamine was found to rise rapidly in rats exposed to cold (6 C). A sevenfold increase above normal is maintained during the 1st month of exposure, but during the 2nd month a decline from these high values is observed, and after 1 year the urine histamine is within normal limits. Similarly, a marked increase in the number of mast cells in the abdominal skin is observed during the first 2 months of cold exposure with a return to initial values by the 4th month. The blood pressure response to intravenous histamine is decreased during the 1st month of cold adaptation but after 1 year in the cold normal sensitivity to histamine is re-established. The excretion of 5-hydroxytryptamine is also rapidly increased during cold adaptation but no decline with time was observed. These findings obtained with histamine are compared with those found previously with noradrenaline. Whereas the urinary levels of these amines show similar variations during cold adaptation, the cardiovascular response differs. The sensitivity to histamine is decreased with increased excretion and the response to noradrenaline increased with increased secretion.
Effects of sympathomimetic amines studied by direct perfusion of the sinus node
Authors: James Thomas N. , Nadeau Reginald A.
Published: December 2017

The effect of epinephrine, norepinephrine, isoproterenol, and ephedrine on normal sinus rhythm has been studied by direct perfusion of the sinus node through its own artery, and compared to the results of stellate stimulation. The maximal sinus tachycardia produced by each of these substances was about the same, and resembled the response to stellate stimulation. To produce maximal tachycardia the doses of epinephrine and norepinephrine were about equal, but were about ten times the dose of isoproterenol required, and one-tenth the dose of ephedrine required. Duration of action of each of the catecholamines was similar, but that of ephedrine was about ten times longer. Dichloroisoproterenol perfused into the sinus node effectively blocked the response to moderate doses of all the test substances but incompletely blocked that to larger doses or the effect of direct stellate stimulation. Subsidence of the effect of the intranodal catecholamines followed a characteristic decay curve.
Effect of an adrenergic blocking agent on vascular alterations associated with endotoxin shock
Authors: Iampietro P. F. , Hinshaw Lerner B. , Brake C. M.
Published: December 2017

The effects of Dibenzyline on the vascular changes associated with endotoxin shock were studied in the dog. Pretreatment with Dibenzyline augmented venous return by decreasing pooling of blood in the liver and probably other areas. The precipitous drop in systemic arterial pressure usually associated with the administration of endotoxin was absent in the Dibenzyline-treated dog, but arterial pressure dropped to the same level as in the nontreated animals within 30 min. Treatment with Dibenzyline had no effect (in 1 hr) on the change in pH, hematocrit, or heart rate.
Influence of ketone bodies on fibrinogen, thrombocytes, and fibrinolysin activity in rabbits
Authors: Brahmankar D. M. , Nath M. C.
Published: December 2017

The elevation of plasma fibrinogen, thrombocytes with concomitant depletion of plasma fibrinolysin activity was observed in animals treated with the sodium salts of ketone bodies (acetoacetate and ß-hydroxybutyrate) for 4, 8, and 12 weeks. While malonate was given together with acetoacetate and ß-hydroxybutyrate the changes were more pronounced. The results indicated the possible influence of disturbance in metabolism of ketone bodies in the development of thrombosis.
Clearance rate in relation to agglutinins for gelatin-stabilized colloid in the rat
Authors: Murray I. MacKay
Published: December 2017

Intravascular clearance rates of gelatin-stabilized gold were compared with circulating titers of gelatin agglutinins in rats at increasing time intervals after blockading injections of gelatin-stabilized gold and S. marcescens endotoxin. The degree and duration of reticuloendothelial system (RES) blockade against the homologous colloid were directly related to the circulating levels of gelatin agglutinins. In contrast, plasma agglutinins were not decreased in endotoxin-induced blockade against the gelatin-stabilized colloid. In a further experiment, the plasma response to blockading injections of colloidal thorium dioxide, iron oxide, and zymosan was characterized by a transient increase in gelatin agglutinins suggesting the nonspecific release of opsonins from an extravascular source. The findings indicated that clearance rates of gelatin-stabilized colloids were dependent on the total available opsonin in the rat rather than the total circulating opsonin. It is suggested that RES blockade is effected by the prior nonspecific depletion of opsonins from an extravascular reserve which is the major component of the total available opsonin.
Relationship of cardiac succinic acid oxidase activity to body weight in the rat
Authors: Jellinek Max , Cooper Theodore
Published: December 2017

Succinic acid oxidase activity was measured in whole heart homogenates of normal male rats weighing from 0.085 to 0.610 kg and was found to vary when expressed on the basis of wet weight of a sample of heart tissue or on its nitrogen content. Young rats tended to have less succinic acid oxidase activity per milligram of cardiac tissue than did older larger rats. However, the activity of the enzyme system of the homogenized whole heart was found to be directly related to the weight of the animal. This relationship can be expressed by the formula: Y = 19.25 + 52.96 ( X – 0.35) where Y is succinic acid oxidase activity of the entire heart in milliliters of O2 per hour, and X is body weight in kilograms. When cytochrome c was added to the reaction mixture, activity was augmented. However, there was a persistent linear relationship between succinic acid oxidase activity of the homogenized whole heart and body weight.
Role of parathyroid hormone in phosphate transport across rat duodenum
Authors: Borle A. B. , Keutmann H. T. , Neuman W. F.
Published: December 2017

The effect of parathyroid extract (PTE) on phosphate transport was studied by perfusing everted duodenal loops of rats in vitro. It was found that PTE had no effect on the membrane potential or on the pH of the medium. However, PTE increased the influx (transfer from mucosa to serosa) 70%, the uptake by the tissue from the mucosal side 30%, and the lactate transfer into the serosal fluid 30%. Outflux of phosphate (transfer from serosa to mucosa) was as great as the influx but unaffected by PTE. Phosphate uptake from the serosal side was a third of the mucosal uptake and also unaffected by PTE. Metabolic inhibitors, iodoacetate, arsenite, and DNP strongly inhibited phosphate influx and tissue uptake. Lactate formation and transfer were also inhibited by iodoacetate and arsenite but not by DNP. In addition the three inhibitors suppressed completely the PTE effects. It is suggested that phosphate movements across the intestine follow different pathways whose dependence upon metabolism, hormonal action, or electrochemical gradient might be different and independent.
Effect of oxytocin, vasopressin, and related peptides on plasma free fatty acids
Authors: Mirsky I. Arthur
Published: December 2017

A significant decrease in the concentration of the free fatty acids of the plasma of nondiabetic or alloxan-diabetic dogs was produced by the intravenous injection of oxytocin, desamino-oxytocin, 3-valine-oxytocin, 2-phenylalanine-oxytocin, arginine-vasopressin, lysine-vasopressin or 2-phenylalanine-8-lysine-vasopressin. The effect is dependent upon the integrity of the disulfide bridge of the various peptides and is attributed to an insulin-like action on adipose tissues.
Dependence of chloride permeability on sodium in the isolated frog skin
Authors: Macey Robert I. , Meyers Stuart
Published: December 2017

By substituting impermeable SO4 ions for 90% of Cl, the response of the potential difference across an isolated frog skin to a tenfold reduction in Cl concentration bathing the external (epithelial) surface was measured while maintaining a constant composition of all other ions. In the presence of Na the external surface does not behave like a Cl electrode, presumably because of the presence of permeable Na ions. However, in the absence of Na (replaced by the relatively impermeable K or Mg ions) the potential response to a tenfold dilution in Cl is much smaller than in its presence. Measurements of Cl36 flux indicate that the Cl conductance is depressed when Na is withdrawn. The results suggest a dependence of the Cl permeability of the external barrier on Na ions.
Rate and affinity in human red blood cell sugar transport
Authors: LeFevre Paul G.
Published: December 2017

Page 286: LeFevre, Paul G., "Rate and affinity in human red blood cell sugar transport." The legend for Fig. 2 should read: Uncertainty in constants as estimated from half-times in Fig. 1. The four curves define the relations between k and K of the type given in equation 4,....

(See PDF for Equation)
Effects of albumin infusion on renal function in the dog
Authors: Elpers Mary Jo , Selkurt Ewald E.
Published: December 2017

Serum albumin (25%) was infused into anesthetized dogs undergoing a saline diuresis. No significant effect was seen on arterial pressure, but renal venous pressure was elevated slightly. GFR remained unchanged, while Cpah, renal plasma flow, total renal blood flow, and flow to medullary tissue increased significantly. Accompanying these changes were marked declines in PAH and creatinine extraction ratios. Urine volume, Cna, and Cosm declined appreciably during albumin infusion; TcHH2O tended to decrease. The ratio of Na and osmolar constituents in renal venous blood to that in arterial blood increased above unity, and calculations indicated that at this time Na was washed from the kidney. Tmpah remained unchanged during albumin infusion. It is concluded that during albumin infusion, there is an increase in plasma volume and renal blood flow accompanied by a diversion of part of this blood through aglomerular regions, possibly through A-V anastomoses, as evidenced by the accompanying decrease in Ecr and Epah. This could involve increased perfusion of the medullary papillary zone, including the vasa recta vessels, supported by the observations that during albumin infusion there is a washout of osmotic constituents, primarily Na, presumably from a zone of high Na concentration.
Effects of exercise and training on serum enzyme and tissue changes in rats
Authors: Highman Benjamin , Altland Paul D.
Published: December 2017

Young adult male rats received 1–20 successively daily 6-hr exercise tests in a rotating cage. Serum glutamic oxalacetic transaminase and aldolase and blood urea nitrogen values rose sharply and serum alkaline phosphatase fell immediately after each of the first four tests with only partial recovery after an overnight rest. Subsequently, the serum alkaline phosphatase and blood urea nitrogen values returned to normal, but the transaminase and aldolase values were slightly elevated even after 17–20 tests. Weight loss was 15% in 3–6 days and 7% after 17–20 tests. Transient fatty changes were noted in the thigh muscles after the first test. Necrotic muscle lesions, most pronounced after three tests, regressed after the 1st week. Rats given 17–20 successive daily 6-hr exercise tests, contrary to untrained rats, showed no apparent fatigue, no muscle lesions, and no significant changes in serum enzymes immediately after a 16-hr exercise test. These findings emphasize the importance of properly graded training exercises.
Effect of exercise on the metabolism of fatty acids in the dog
Authors: Miller H. , Issekutz B. , Rodahl K.
Published: December 2017

Dogs with indwelling arterial and venous catheters worked on a treadmill for 25–30 min. Exercise decreased the plasma free fatty acid (FFA) concentration and increased the blood glucose. In the postexercise period, the plasma inorganic P showed a significant decrease. Experiments with C14-palmitate and C14-oleate showed that the decrease of the plasma FFA was due partly to an elevated uptake and partly to a reduced rate of release into the blood. Infusions of Na lactate to resting dogs induced a marked increase in specific activity of plasma FFA, due to an inhibition of release. In spite of the reduced rate of release of FFA, the oxidation of the C14-fatty acid was considerably increased during exercise (three- to fourfold). No direct relationship seems to exist between the turnover rate of plasma FFA and the rate of oxidation of fatty acids.
Concentrative and reversible character of intestinal amino acid transport
Authors: Christensen Halvor N. , Feldman Bruce H. , Hastings A. Baird
Published: December 2017

Either α-aminoisobutyric acid-1-C14 or 1-aminocyclopentanecarboxylic acid-1-C14 was injected into a rat and, after at least 24 hr, a suitable dilution of the same solution of the amino acid was introduced into an intestinal loop in situ and the change in its distribution observed by radioisotope counting. The two amino acids could be concentrated from the small intestine to establish steady-state distribution ratios of from 12 to 100, for the plasma level with respect to the level in the lumen. These values are far higher than the distribution ratios produced across excised intestine. These steady-state values were approached from either above or below, by absorption or release of the amino acid. The release was accelerated by the presence of the same or another amino acid of high transport affinity in fluid perfusing the intestinal loop, an action that tends to identify the outward migration from lumen to plasma with a transport process. The test amino acids were released into the colon also, although at slower rates, the steady-state distribution ratio lying in the neighborhood of unity. This release appears also to be a specific process, and to account for the slow fecal excretion of these difficultly metabolized amino acids.
Role of chloride ions in cardiac action and pacemaker potentials
Authors: de Mello Walmor Carlos
Published: December 2017

Evidence is presented that chloride ions are able to carry an appreciable amount of electric charge through the membrane of atrial muscle fibers, Purkinje fibers, and fibers of the S-A nodal pacemaker. An increase in the slope of diastolic depolarization of pacemaker fibers was recorded when Cl– was replaced by larger anions (sulfate) in the external medium. The rate of repolarization decreased when larger anions were substituted for chloride ions, and it was increased in nitrate or bromide solutions. The anionic permeability of the cell membrane of S-A node, atrial muscle, and Purkinje fibers seems to follow the series: NO3– > Br– > Cl– > CH3COO– > SO4= Evidence is presented that chloride ions contribute to diastolic depolarization of pacemaker fibers. The K+ electrode properties of resting membrane of fibers of the S-A node were investigated at low and at constant extracellular Cl– concentration. It was found that above 16 mm K2SO4 there is agreement between the resting potential and Ek. Below this K+ concentration a deviation of the resting potential from the line for a K+ electrode was observed. Determinations of the Cl– content and of volume changes support the idea that the membrane of fibers of the S-A node and atrial muscle is permeable to Cl– and to K+ ions.
Effects of acid-base changes and carbonic anhydrase inhibition on pancreatic secretion
Authors: Rawls James A. , Wistrand Per J. , Maren Thomas H.
Published: December 2017

Pancreatic flow and HCO3– and Cl– output were studied in dogs following 2 U/kg (i.v.) of secretin. Acetazolamide reduced flow and HCO3– output to half normal. HCl produced the same effect. NaHCO3 increased flow and HCO3– output. CO2 produced little change. Severe hyperventilation decreased flow and HCO3– output. Results are consistent with secretion dependent on the over-all reaction OH– + CO2 → HCO3–, with both a carbonic-anhydrase catalyzed and an uncatalyzed component. Reduction of either reactant or of enzyme decreased output: increase of the reactants increased output. From in vitro kinetics and analysis of rates in vivo, the role of carbonic anhydrase may be assessed. About half of HCO3– output normally depends on the uncatalyzed reaction, and half on the catalyzed. In metabolic alterations, only the uncatalyzed component is affected. Pancreatic carbonic anhydrase is greatly in excess of that needed for the observed catalyzed rate in vivo. Correspondingly, reduction of output by acetazolamide occurs only when >99% of pancreatic carbonic anhydrase is inhibited. It is suggested that the rate-limiting event in pancreatic HCO3– secretion is transport of HCO3– from cell to duct.
Effects of intrahypothalamic crystalline steroids on acute ACTH secretion
Authors: Chowers Israel , Feldman Shaul , Davidson Julian M.
Published: December 2017

The respective roles of the hypothalamus and pituitary gland, in the inhibition of adrenocorticotropin secretion by corticoids, were studied by implanting small quantities of crystalline cortisol acetate in the median eminence region and pituitary of male rats. Adrenal weights and adrenal ascorbic acid depletion (AAAD) in response to the acute stress of unilateral adrenalectomy were measured 5, 10, 13, or 21 days postoperatively. Ten days following implantation in the hypothalamus, rats showed adrenal atrophy and inhibition of AAAD. Normal AAAD and slight adrenal hypertrophy were found 10 days after similar implantation of testosterone propionate in the median eminence. Animals with cortisol implants in the pituitary had normal adrenal weights and AAAD responses at this time. In rats with cortisol implants in the hypothalamus, an inhibition of AAAD was present after 5–6 days, had increased maximally at 13 days, and returned to normal at 21 days. Adrenal atrophy, however, was first noted at 10 days and adrenal weight continued to decline throughout the experimental period.
Diffusion of tritiated water into collecting duct urine in the dog
Authors: White H. L. , Rolf Doris
Published: December 2017

When tritiated water is infused during stopped flow in the dog the renal papilla is 8.7% as well labeled as is the cortex, when no urine is permitted to escape. With urine escape, the first urine from the collecting ducts is only 4.5% as well labeled as is the cortex, and the last urine (cumulative volume up to 4.5 ml) is considerably less labeled than are the papillae from which it has just emerged. We thus find that in our present series (kidneys frozen before sectioning), as well as in our earlier series with nonfrozen kidneys, diffusion equilibration of tritiated water between papilla tissue water and collecting duct urine is incomplete in the dog.
Induced modulations in autonomic efferent neuron activity
Authors: Koizumi Kiyomi , Suda Isamu
Published: December 2017

A study was made of the extent to which autonomic responses follow stimulation of the cerebellar cortex, somatic, and visceral afferent nerves. Activity of units in splanchnic and mesenteric nerves, in postganglionic fibers from the coeliac ganglion, and in vagus nerve branches to the stomach was recorded by microelectrodes. Stimulation of visceral, muscle, and skin afferents evoked discharges in sympathetic fibers and augmented their spontaneous activity. Sympathetic and parasympathetic efferents showed reciprocal action in that, when activity in one was either spontaneously or reflexly increased, activity in the other diminished. Chemical stimulation of the cerebellar cortex by application of sodium glutamate produced an increase in activity of both sympathetic and parasympathetic nerves and an increase in systemic blood pressure. Changes in blood pressure also modified activities of the autonomic efferents. The spontaneous discharges were not much affected by decerebration or decerebellation but section below the medulla at least temporarily abolished tonic activity in the units studied.
Preganglionic discharge to the cardiovascular system in the comatose cat
Authors: Tuttle Richard S.
Published: December 2017

A technique for isolating and recording from single fibers in the thoracic spinal canal permits access to the entire preganglionic outflow of the thoracic spinal cord of the cat. In the cat rendered comatose by the selective destruction of the brain stem, there are two interchangeable patterns of impulse activity which reflect the level of systemic blood pressure. Periodic bursts of high-frequency discharge, synchronous with the respiratory cycle, are replaced by continuous activity when increased sympathetic discharge to the cardiovascular system is evoked by hypothalamic stimulation or by reflex mechanisms. The data suggest that impulse pattern as well as frequency of stimulation may be a factor of importance in the sympathetic organ response to direct stimulation of the innervating postganglionic nerve.
Placental transfer of insulin-binding antibodies in the guinea pig
Authors: Meade Robert C.
Published: December 2017

Insulin-binding antibodies were demonstrated in the serum of fetuses and newborn of insulin-treated guinea pigs. The antibody concentrations in fetal and maternal sera were comparable. Following delivery, the antibody decreased more rapidly in the newborn than in the mother. Antibodies injected into the maternal circulation were demonstrable in increasing concentration in the fetal circulation from 12 to 120 hr after maternal injection. These studies favor a mechanism of passive transplacental transfer of anti-insulin antibodies.
Separation of pepsin I, pepsin II A, pepsin II B, and pepsin III from human gastric mucosa
Authors: Seijffers Max J. , Segal Harry L. , Miller Leon L.
Published: December 2017

Extracts of human gastric mucosa have been fractionated on diethylaminoethyl cellulose to yield three precursors of proteolytic enzymes active at low pH which have been called pepsinogen I, pepsinogen II, and pepsinogen III. Pepsinogen I has been found in the mucosa from all parts of the stomach examined as well as in the proximal duodenum. Pepsinogen II and pepsinogen III were present in fundic mucosa only.
Separation of pepsinogen I, pepsinogen II, and pepsinogen III from human gastric mucosa
Authors: Seijffers Max J. , Segal Harry L. , Miller Leon L.
Published: December 2017

Extracts of acidified human gastric fundic mucosa have been fractionated on diethylaminoethyl cellulose to yield three pepsin fractions, which have, in order of their elution, been attributed to pepsin I, pepsin II A, and a mixture of pepsin II B and pepsin III. Acidification of previously purified pepsinogen I and pepsinogen III yields pepsin I and pepsin III, respectively. Acidification of previously purified pepsinogen II yields two distinct pepsin fractions, pepsin II A and pepsin II B. Pepsin II B and pepsin III have the same chromatographic mobility on diethylaminoethyl cellulose, but are probably not identical. Pyloric and duodenal mucosa yield only pepsin I upon acidification. Human pepsin-pepsin inhibitor complex is demonstrable as a chromatographic fraction distinct from pepsins upon fractionation of acidified dilute pepsinogen solutions with diethylaminoethyl cellulose equilibrated with acetate buffer pH 5.3.
A functional study of distribution of cardiac sympathetic nerves
Authors: Randall Walter C. , Priola Donald V. , Ulmer Richard H.
Published: December 2017

In dogs with unilaterally sympathectomized hearts, the remaining intact stellate ganglion was electrically stimulated 14–58 days following sympathectomy. Pressures were simultaneously recorded from all four chambers of the heart and the resulting responses compared with those observed in similarly stimulated but nonsympathectomized animals. Augmentor responses were markedly decreased in some animals but relatively unchanged in others, and it is evident that considerable variation exists in the distribution of sympathetic fibers in different animals. A common finding was markedly delayed augmentation in which responses were practically absent during the initial periods of stimulation. Chronotropic responses appeared to be largely dependent upon intact connections via the right sympathetic nerves. It may be concluded that the sympathetic cardiac nerves from the right side go primarily to the atria and nodal tissue, with a variable supply to the ventricles. In some animals the latter supply is very large while in others it is minimal. The left sympathetic cardiac nerves furnish the major supply to the ventricles, with variable but generally lesser distribution to the atria.
Relation of thyroid state to myocardial catecholamine concentration
Authors: Kurland George S. , Hammond Rupert P. , Freedberg A. Stone
Published: December 2017

The myocardial catecholamine content was measured in euthyroid, thyrotoxic, and hypothyroid rabbits. Male rabbits were made thyrotoxic by injection of l-thyroxine, or were rendered hypothyroid by injection of I131. Body weight, basal metabolic rate, serum protein-bound iodine, and appearance were used as criteria of thyroid state. Myocardial norepinephrine and epinephrine concentrations were measured, after alumina column chromatography, by a modification of the trihydroxyindole method. Fluorescence spectra and paper chromatographic analyses confirmed the identity of the trihydroxyindole-fluorescing material, and revealed no extraneous fluorescing substances. In the heart of the euthyroid rabbit, epinephrine concentration averaged 0.3 ± .2 (sd) µg/g in the atrium, and 0.06 ± .03 µg/g in the ventricle. Norepinephrine concentration averaged 2.9 ± .4 µg/g in the atrium, and 2.2 ± .3 µg/g in the ventricle. In thyrotoxicosis, atrial epinephrine and norepinephrine concentrations were decreased, ventricular epinephrine was unchanged, and ventricular norepinephrine was decreased. In hypothyroidism, atrial epinephrine and norepinephrine were decreased and ventricular epinephrine was unchanged, but in the hypothyroid ventricle, norepinephrine content was markedly increased.
Effect of temperature and continuous stimulation on gastrocnemius of the frog
Authors: Osgood P. F. , Brewster W. R.
Published: December 2017

Gastrocnemius muscles of the winter frog ( Rana pipiens) were stimulated directly, at a rate of 2/sec at temperatures of 10, 15, 20, 25, and 30 C and at 1/sec at 5 C. Isometric strain-gauge recordings showed that at all temperatures, when developed tension remained constant, the duration of contraction remained relatively unchanged, while the duration of relaxation progressively increased. The prolongation of relaxation was most rapid and striking at 5 C, becoming progressively less with increasing temperature. These findings suggest that relaxation may be the phase of greatest metabolic activity.
Acute asphyxiation of the spinal cord and of other sections of the nervous system
Authors: Harreveld A. Van , Biersteker P. A.
Published: December 2017

Oxygen lack causes an impedance increase of the spinal cord coinciding in time with an asphyxial potential which can be led off from the spinal gray matter against an indifferent electrode. After circulatory arrest the latency of these changes is of the order of 10 sec; after ventilation of the preparation with nitrogen the latency is 20–25 sec. An asphyxial transport of chloride was demonstrated into dendrites of dorsal horn neurons accompanied by a volume increase of these structures. The electrolyte movement can account for the impedance increase by a loss of extracellular ions which are the main carriers of the measuring current. The observed ion movement, taken as an indication of depolarization, suggests that the asphyxial potential is due to dendritic depolarization, the somas (and axons) acting as source. This explanation was supported by the much slower decline of the spinal asphyxial potential as compared with that of a similar potential which can be led off from the cerebral cortex. The difference in the rate of decline reflects the much slower asphyxial depolarization of the somas of spinal neurons as compared with that of cerebral nerve cell bodies which has been observed previously.
Distribution of thiocyanate between plasma and cerebrospinal fluid
Authors: Streicher E. , Rall D. P. , Gaskins J. R.
Published: December 2017

Relatively small amounts of thiocyanate are found in the cerebrospinal fluid (CSF) at plasma levels below 1 mm/liter. Starting at plasma concentrations of about 1.5 mm/liter, a relatively constant plasma-CSF differential of approximately 1.2 mm/liter is established and maintained. This concentration difference, which essentially represents the "blood-CSF barrier" to thiocyanate is reversibly reduced by the intracisternal administration of hypertonic solutions.
Renal handling of exogenous and metabolic carbon dioxide
Authors: Chinard Francis P. , Nolan Mary F. , Enns Theodore
Published: December 2017

The multiple-indicator-dilution technique has been applied to a study of the permeability of proximal and distal portions of the nephrons to dissolved carbon dioxide and bicarbonate ion in anesthetized dogs. Under control conditions with mannitol loading, the excreted carbon dioxide appears considerably earlier than the simultaneously injected creatinine whether dissolved CO2 or bicarbonate ion is injected. After inhibition of carbonic anhydrase by acetazolamide, there is relatively little effect on the excretion pattern of dissolved CO2. However, the excretion pattern of bicarbonate ion becomes nearly parallel to that of creatinine: the early peak disappears. On the basis of these results, it is concluded that the distal portions of the nephrons are permeable to dissolved CO2 but impermeable to bicarbonate ion and that, under control conditions, carbonic anhydrase serves to establish a catalytically mediated diffusion exchange for the transfer of CO2 derived from bicarbonate ion. Similar conclusions may apply to the proximal portions of the nephrons. On taking into account other data, it appears that the collecting ducts are impermeable to dissolved carbon dioxide. Carbon dioxide produced by decarboxylation of pyruvate has excretion patterns similar to those obtained for dissolved carbon dioxide. It is concluded that the decarboxylation product is dissolved CO2 and not bicarbonate ion.
Effects of metabolic inhibitors on the rat uterus and on its response to oxytocin
Authors: Marshall Jean M. , Miller Mary D.
Published: December 2017

Myometrial strips from white rats between the 6th and 9th and the 20th and 22nd days of pregnancy were arranged for the simultaneous recording of membrane potentials from single muscle fibers and isometric tension from the entire strip. The 6- to 9-day uteri behaved as though they were progesterone controlled, while the 20- to 22-day muscles seemed to be under the control of estrogen. Dinitrophenol (DNP) (10–3 m) depolarized the muscle cell membrane and stopped all contractions in the 6- to 9-day uteri, but only diminished the contractions in the 30- to 22-day muscles. In both groups of muscles, DNP (10–3 m) abolished the stimulatory action of oxytocin. The inhibitory action of DNP was reversible. Monoiodoacetic acid (IAA) (2 x 10–4 m) abolished all activity and the response to oxytocin in both groups of muscles but, in contrast to DNP, there was no change in the level of the resting membrane potential. The action of IAA was irreversible.
Acetoacetate turnover and oxidation rates in ovine pregnancy ketosis
Authors: Bergman E. N. , Kon K.
Published: December 2017

Labeled acetoacetic acid (AcAc) was administered as a tracer dose and as a continuous infusion to 24 twin-pregnant ewes with varying degrees of spontaneous or fasting hypoglycemic ketosis. The mean AcAc turnover rate of five normal twin-pregnant sheep (plasma AcAc < 1 mg/100 ml) was only 0.04 g/hr kg3/4 or 1.0 g/sheep hr. During ketosis the turnover rate of AcAc was directly proportional to the plasma AcAc concentration until a maximal concentration of about 10 mg/100 ml was attained (total ketone bodies, expressed as acetone, would be about 20 mg/100 ml). At higher plasma concentrations, the AcAc turnover rates remained constant at nearly 0.4 g/hr kg3/4 (9 g/sheep hr). About one-half of this AcAc was oxidized to CO2 regardless of the actual amount utilized. The mean percentage of the total exhaled CO2 derived from AcAc metabolism increased from 2% in normal ewes to a maximum of about 20% during pregnancy ketosis. Comparisons of these data to values obtained in previous experiments on artificially ketotic nonpregnant sheep indicate that an overproduction of ketone bodies, rather than an underutilization, is the major cause of ruminant ketosis.
Cellular localization of gastric intrinsic factor in the rat
Authors: Boass Agna , Wilson T. Hastings
Published: December 2017

The distribution of carbonic anhydrase, pepsinogen, and intrinsic factor (IF) was studied in frozen sections of rat gastric mucosa using the method of Holter and Linderstrøm-Lang. Carbonic anhydrase activity was greatest in the sections nearest to the surface of the mucosa and less in the deeper regions of the glands. In contrast, the levels of both IF and pepsinogen were low at the surface and continued to increase to a maximum at the base of the gastric glands. The close correlation between the distribution of the concentrations of pepsinogen and IF suggests that the chief (zymogenic) cell may be the source of IF in the stomach of the rat. No IF was detected in human carcinoid tumor tissue. This absence of IF is consistent with the view that the argentaffine cell is not the source of IF.