bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of elastic properties of a 550-µ artery in vitro
Authors: Hinke J. A. M. , Wilson M. L.
Published: December 2017

A technique is described for mounting a 3-cm length of the rat tail artery (550 µ o.d.) in a way that permits fluid to flow through its lumen. The diameter of the segment was measured at increasing intraluminal pressures and flow rates. Normally the artery segment distended with increasing pressures up to 100 mm Hg, but when 0.5 µg/ml norepinephrine was perfused it constricted to a radius which remained constant over this pressure range. "Elastic diagrams" were constructed from the distensibility curves for the artery wall with and without active drug-induced tension. From the linear part of the diagram, Young's modulus was calculated to be 4.5 x 105 dynes/cm2 for the wall and 0.8 x 105 dynes/cm2 for the "resting" smooth muscle (75% of wall) of the wall. The significance of wall elasticity with respect to the state of the artery in situ is discussed.
Rapid method for study of enzyme distribution in rat kidney
Authors: Waldman R. H. , Burch Helen B.
Published: December 2017

A rapid method for localizing enzymatic levels in various structures of the kidney is described. This method consists of dissecting a cone from rapidly frozen kidney, and measuring the enzyme activities of thin slices from the cortex to the papilla. The use of this method in elucidating the distribution of d- and l-amino acid oxidases and of hexokinase and glucose 6-phosphatase in adult rat kidney and of the last two enzymes in young rat kidney from birth to weaning is reported. Glucose 6-phosphatase was most active in the cortex and least active in the papilla in all age groups. The site of maximum glucose 6-phosphatase activity coincides with the alleged site of glucose reabsorption. Hexokinase was highest in the papilla and lowest in the outer cortex in most ages. l- Amino acid oxidase was concentrated in the midcortex, and d-amino acid oxidase in the border between the cortex and medulla.
Sodium fluxes in the Ehrlich mouse ascites tumor cell
Authors: Aull Felice , Hempling H. G.
Published: December 2017

Na+ transport was measured in the Ehrlich mouse ascites tumor cell by isotopic and chemical methods. Evidence for an initial, rapidly exchanging Na+ compartment was found in addition to a slower compartment. Net Na+ efflux might constitute less than half the total efflux. Influx of Na+ decreased while intracellular Na+ was falling, demonstrating a dependence of Na+ influx on intracellular Na+ content. Taken together, the data provide evidence for a component of Na+ transport which is mediated but not active.
Compartment analysis of the radiorenogram and distribution of Hippuran I131 in dogs
Authors: Blaufox M. Donald , Orvis Alan L. , Owen Charles A.
Published: December 2017

Radioiodinated Hippuran was injected into the inferior vena cava of three unilaterally and three bilaterally nephrectomized dogs. Radioactivity was recorded over the precordium and remaining kidney in the former group and the precordium and renal fossa in the latter. The disappearance of I131 from plasma was analyzed and interpreted by two-compartment and three-compartment systems. Theoretical curves for cardiac and renal areas (constructed from analysis of arterial plasma samples) agreed well with curves from in vivo counting. Analyzed by either model, the first compartment exceeded the plasma volume severalfold, part seeming to be in the kidney. Extravascular compartments, impossible to sample, were not identified. About 15% of whole-blood radioactivity was in erythrocytes. Biliary excretion of Hippuran I131 was insignificant unless nephrectomy was bilateral; then up to 60% was excreted in the bile in 24 hr. Protein binding could not be demonstrated. Radiorenograms converted to fairly accurate rate constants may prove more useful than descriptive methods currently employed. Understanding the distribution and excretion of Hippuran appears helpful to accurate interpretation of the radiorenogram.
Effect of metabolic inhibitors on urine osmolality and electrolyte excretion
Authors: Herms Wolfgang , Malvin Richard L.
Published: December 2017

The in vivo effects of aerobic and anaerobic metabolic inhibitors on renal Na and K transport and concentrating ability were studied in dogs. Two aerobic inhibitors (sodium cyanide and hydroxylamine) and two anaerobic inhibitors (iodoacetate and triethyleneiminotriazine) were infused into one renal artery. Urine was collected separately from both kidneys and urine osmolality, Na, and K concentrations were measured. In addition, stop-flow experiments were done before and after infusion of NaCN and iodoacetate into one renal artery. Aerobic inhibitors resulted in a decrease in urine osmolality associated with a large increase in Na excretion. Anaerobic inhibitors resulted in a similar decrease in urine osmolality with only a minimal increase in Na excretion. In stop-flow experiments cyanide blocked Na and K transport in the distal tubule. Iodoacetate had no demonstrable effect on distal Na or K transport, but did abolish K secretion which was presumed to take place in the collecting ducts. These results suggest that Na and K transport in medullary regions is largely dependent on energy derived from anaerobic glycolysis.
Initiation and conduction of impulses in partially depolarized cardiac fibers
Authors: Van Dam R. T. , Moore E. Neil , Hoffman B. F.
Published: December 2017

The propagation of impulses in partially depolarized cardiac fibers has been studied by stimulating isolated preparations of mammalian Purkinje fibers or ventricular muscle at selected intervals during and after repolarization. Electrical activity has been recorded simultaneously through multiple intracellular microelectrodes located at various distances from the stimulus site. Three possibilities appear to exist for conduction during the latter part of repolarization in cardiac fibers which contrast with conduction occurring after the completion of repolarization: 1) Slow conduction. This has been observed when the action potential propagates into fibers in which repolarization is less advanced. This may be associated with a decrease in the rate of rise and the voltage of the action potential and corresponds more or less to decremental conduction. When entering more fully repolarized fibers, the action potential may show reverse changes. 2) Conduction at normal velocity. This has been observed when impulses propagate in fibers which are more or less in the same stage of repolarization even though the transmembrane potential may not be of normal magnitude. 3) Fast conduction. The present study offers no clear evidence for this type, which should correspond to the so-called supernormality of conduction. In contrast, apparent supernormal conduction was shown to be caused by a shift of the site of origin of the action potential when stimuli were applied during the relative refractory period.
Mechanism of beta-mercaptoethylamine-induced hypotension in the dog
Authors: Mundy Roy L. , Heiffer Melvin H. , Mehlman Benjamin
Published: December 2017

Radioprotectant doses of beta-mercaptoethylamine (MEA) are toxic to the dog, inducing hypotension and hemoconcentration. Antihistaminics and two adrenergic blocking agents with antihistaminic properties were effective against MEA-induced hypotension. Adrenergic blocking agents with little antihistaminic action were ineffective against the hypotension. Antihistaminic compounds blocked MEA-induced hemoconcentration caused by a loss of plasma from the circulation, a portion of which may be found in the peritoneal cavity. Loss of plasma from the circulation and appearance of fluid in the peritoneal cavity is partially prevented by antihistaminics. MEA causes dermal whealing similar to that produced by histamine, and this whealing is prevented by intravenously administered pyrilamine maleate. These findings are interpreted as meaning that histamine release plays an important role in MEA-induced toxicity.
Renal tubular transport of citrate: relations with calcium
Authors: Vishwakarma P. , Miller T.
Published: December 2017

The renal excretion of citrate and calcium was studied in the dog during the infusion of these substances alone or together by the stop-flow method. Citrate per se was found to be reabsorbed only in the proximal tubular area. This reabsorption occurred against marked concentration gradients. Spontaneous variations in the urine pH from 6.11 to 7.11 units did not affect the reabsorption in any way. Infusion of bicarbonate decreased the capacity of the proximal tubule to lower the citrate concentration but did not alter the general pattern of its transport along the nephron length. Calcium without citrate was actively reabsorbed only in the distal tubule. Calcium when given with citrate, did not affect the pattern of citrate transport along the length of the nephron. Citrate did not affect the distal reabsorption of calcium. However, it did produce a proximal reabsorption of calcium. It was postulated that the proximal reabsorption of citrate is active. The molecular requirement for reabsorption of citric acid is discussed.
Secretion of cerebrospinal fluid by choroid plexus of the rabbit
Authors: Welch Keasley
Published: December 2017

Blood flow in the principal draining vein of the choroid plexus of the lateral ventricle of the rabbit, which drains approximately the anterior 70% of the plexus, was measured by the analysis of motion pictures made during the injection of spheruler of 1-octanol. The relative loss of volume from the plasma compartment during the transit of blood was measured by the comparison of relative cell volumes in aortic blood and in venous blood of the plexus. The blood flow of the plexus averaged 2.86 µl/mg min and the rate of production of cerebrospinal fluid .37 µl/mg min. The effect upon the relative rate of production of fluid of several inhibitors was tested and of these acetazolamide was effective both intravascularly and topically; cardiac glycosides were effective topically, but not when given intravenously; and cyanide and 2,4-dinitrophenol were ineffective topically.
Site of reabsorption of citrate and calcium in the renal tubule of the dog
Authors: Grollman Arthur P. , Walker W. Gordon , Harrison Helen C. , Harrison Harold E.
Published: December 2017

Simultaneous reabsorptive patterns of calcium, citrate, sodium, potassium, creatinine, and para-aminohippurate (PAH) were determined by stop-flow technique during the infusion of calcium chloride and the neutral sodium salts of malate, citrate, and ethylenediaminetetraacetate (EDTA). Citrate reabsorption during citrate infusion occurred in the proximal nephron, coinciding with the area of PAH secretion while the calcium reabsorptive minimum was in the distal tubule, coinciding with the pattern of sodium reabsorption. Malate infusion abolishes citrate reabsorption, stimulates the distal secretion of potassium and, despite the marked increase in citrate excretion, fails to increase citrate concentration in renal tissue samples. EDTA infusion obliterates the calcium reabsorption minimum without affecting the more proximal pattern of citrate reabsorption. It is concluded that maximum citrate reabsorption occurs in the proximal region of the nephron distinctly separate from the more distal region of maximum calcium reabsorption.
Effect of Ca on duration of Q-T interval and ventricular systole in dog
Authors: Surawicz Borys
Published: December 2017

The relation between the duration of the Q-T interval and of the left ventricular systole was studied in dogs with induced hypo- and hypercalcemia. At all studied Ca concentrations the change in the duration of both intervals was of similar magnitude and the relation between the duration of Q-T and ventricular systole was nearly constant as long as the heart rate was regular and the ventricular end-diastolic pressure did not change abruptly. Changes in the Q-T duration were due to changes in the duration of the interval from the end of QRS to the apex of T. In the postextrasystolic beats and during alternans the duration of left ventricular systole changed independently of the duration of the Q-T interval. It was concluded that the ventricular systole adjusts its duration to the duration of repolarization, more specifically to the duration of the plateau of the ventricular action potential, within a wide range of Ca concentrations. An escape from this adjustment occurs when the ventricular filling pressure or volume changes abruptly.
Pulmonary hemodynamics in respiratory acidosis in dogs
Authors: Linde Leonard M. , Simmons Daniel H. , Lewis Norman
Published: December 2017

Pulmonary vascular resistance of intact anesthetized dogs rose during constant ventilation with 5–8% CO2. This rise was not due to mechanical effects of decreased pulmonary artery or left atrial pressures or to decreased cardiac output, but appeared to be due to active pulmonary vasoconstriction. The increased pulmonary vascular resistance during CO2 breathing was eliminated by either adrenalectomy or sham operation, but not by acute hemorrhage, indicating that some mechanism other than blood loss accounted for the failure of response. This effect of operation may explain the variation in results previously reported. The mechanism is not known, but may be related to altering adrenal medullary secretions, which are known to cause pulmonary vasoconstriction. The response to CO2 was not restored in adrenalectomized animals by administration of maintenance or extra hydrocortisone, suggesting that the failure of pulmonary vascular resistance to rise in laparotomized animals was not due to adrenocortical depletion following surgery.
Kinetics of p-aminohippurate secretion in the rabbit
Authors: Foulkes E. C.
Published: December 2017

A technique is proposed and tested which permits the calculation of the size and turnover rate of the p-aminohippurate (PAH) secretory pool in the renal cortex of the rabbit in vivo. The secretory pool is here defined as the cellular solute compartment with which secreted solute equilibrates during its transcellular movement from plasma into tubular urine. The calculations are based on the rate of isotopic equilibration of plasma and urine under steady-state conditions. From the influence of various drugs on the characteristics of the secretory pool, it is inferred that 1) similar PAH carrier mechanisms mediate influx into, and outflux from, the secretory pool, and 2) the PAH accumulated within the cells is coextensive with the secretory pool and is present in a free rather than bound form.
Effect of d-l-ethionine on electrolyte secretion of the dog pancreas
Authors: Feldman Morton , Dreiling David A. , Paulino-Netto Augusto , Schaffner Fenton , Janowitz Henry D.
Published: December 2017

The secretion of fluid and electrolytes, as well as amylase, was studied in response to secretin and pancreozymin stimulation in unanesthetized dogs fitted with a Thomas-type duodenal fistula by inserting a cannula directly into the main pancreatic duct before and during a 3-week period of ethionine administration. In addition to the well-established destructive effect of d-l-ethionine on the acinar cell and its secretion of enzymes, changes occurred in the secretion of HCO3 and H2O in response to secretin. During the early phase of ethionine intoxication (weeks 1–2) HCO3 concentration fell despite preservation of the volume rate of flow. During the second and third weeks, HCO3 concentration was preserved despite marked reduction in volume rate of flow. It is suggested that these findings may be correlated with changes in ductular as well as acinar cells. Na and K concentration, juice osmolality, and the reciprocal Cl-HCO3 relationship were unaltered.
Factors influencing control of arterial circulation in the liver of the dog
Authors: Cohn Roy , Kountz Samuel
Published: December 2017

Measurements were made of the hepatic arterial flow in thirty-one mongrel dogs by the use of the electromagnetic square wave flowmeter under the following experimental conditions: hepatic arterial neurectomy, portal venous flow reductions, portal venous flow elimination and diversion, and systemic acidosis and alkalosis. The findings suggest that the periarterial nerves about the hepatic artery influence the intrinsic regulation of hepatic artery blood flow only in the presence of severely reduced portal venous flow.
Glucose oxidation in the alloxan-diabetic rat
Authors: Depocas Florent
Published: December 2017

Rates of turnover, excretion, and oxidation of glucose have been measured in alloxan-diabetic rats and compared to values obtained in normal rats under similar conditions. Alloxan-diabetic rats showed almost normal rates of glucose uptake (turnover rate-excretion rate) but at levels of plasma glucose approximately 3.4 times normal. Under these conditions the ratio of oxidation rate to uptake rate of glucose in alloxan-diabetic rats was very close to that measured in normal animals, thus indicating that lowered availability of insulin does not modify the pattern of intracellular regulation of glucose oxidation which in the normal animal is a function of the rate of glucose uptake by the tissues.
Free fatty acid metabolism by skeletal muscle
Authors: Spitzer John J. , Gold Martin
Published: December 2017

Removal and oxidation of free fatty acids (FFA) were studied by the electrically stimulated skeletal muscle in dogs receiving an infusion of I-C14-palmitate, oleate, linoleate, or octanoate. Resting skeletal muscle removed about 43% of the arterial FFA. The A-V difference was directly proportional to the arterial FFA level. During electrical stimulation the removal increased due to the increased blood flow while the extraction ratio decreased. A portion of the infused carbon 14 appeared in the venous blood as C14O2 in all animals receiving either long-chain fatty acids or octanoate. The specific activity of C14O2 in the venous blood became higher than that in the arterial blood during stimulation when long-chain fatty acids were infused, but did not undergo such changes when octanoate was infused. No differences were observed between the different groups of animals receiving the various long-chain fatty acids. It is postulated that only a fraction of the removed FFA is immediately oxidized, while a portion is stored and oxidized at a later date.
Protein metabolism in cardiac hypertrophy and heart failure
Authors: Gudbjarnason Sigmundur , Telerman Michael , Bing Richard J.
Published: December 2017

The rate of myocardial protein synthesis was studied in hearts of normal rabbits and in hearts of animals with experimentally produced cardiac hypertrophy and with acute and chronic myocardial failure. Cardiac hypertrophy was accompanied by an increase in protein synthesis; however, there was no increased myocardial protein turnover rate. In acute heart failure the rate of myocardial protein synthesis was diminished as compared to protein synthesis during the development of cardiac hypertrophy. In chronic heart failure the relative incorporation of glycine-2-C14 into heart muscle protein was diminished. The turnover rate of myocardial proteins during cardiac hypertrophy was not altered.
Maximal secretory capacity of the canine pancreas in response to pancreozymin and secretin
Authors: Hansky J. , Tiscornia O. M. , Dreiling D. A. , Janowitz H. D.
Published: December 2017

The output of amylase in nine dogs with chronic pancreatic fistulae has been studied in response to continuous infusions and single intravenous injections of pancreozymin and dose-response curves obtained. A maximal secretory response was reached by each form of administration of the hormone, supramaximal doses giving no further increase. By combining the maximal pancreozymin dose with a maximal secretin dose in a single injection, the maximal amylase, fluid, and bicarbonate secretory capacity of the dog pancreas was determined. On the average, maximal response to pancreozymin was obtained with 0.5–2.0 U/kg min given as a continuous infusion, with 10–25 U/kg as a single injection, and with a dose of 5–15 U/kg when combined with 8 U/kg secretin (maximal dose). In all experiments variability was least at maximal doses. With the combined pancreozymin-secretin injection the mean maximal 15-min output of fluid was 25.7 ml, of amylase 364 U, and of bicarbonate 3.15 mEq.
Acid-base changes in brain and skeletal muscle of maturing rats
Authors: Withrow C. D. , Woodbury Dixon M. , Wilcox W. D.
Published: December 2017

Tissue acid-base changes during maturation were studied by making complete acid-base comparisons among 8-day-old, 25-day-old, and adult rats. Micromethods were used to obtain individual values for blood pH and for CO2 content of plasma, brain, and skeletal muscle. The results showed that the CO2 content of both brain and muscle are high in 8-day-old animals but decrease to adult levels in the 25-day-old rat. Plasma total CO2 does not change during maturation. Fractionation of muscle total CO2 into extra- and intracellular components indicated that muscle cell pH is elevated in 8-day-old animals because intracellular bicarbonate levels are markedly greater than those observed in older animals. It was concluded that changes in tissue CO2 content during growth are due to a marked decrease in intracellular bicarbonate concentrations. Although the partition of brain total CO2 was not feasible due to uncertainties in extracellular space measurements, the results indicated that during maturation brain cell acid-base parameters undergo changes similar to those observed in skeletal muscle.
Two mechanisms of sulfate-S35 uptake by blood platelets of rats
Authors: Odell T. T. , McDonald T. P.
Published: December 2017

Labeling of blood platelets of rats with sulfate-S35 was studied during the 32-hr period following a single injection of this isotope. A decline in platelet radioactivity during the first 12 hr followed by a rise was observed, indicating an early, short half-time labeling of circulating platelets and a less rapid appearance in the circulatory system of platelets labeled in the hemopoietic tissue. The compound that is labeled during the early period seems relatively labile, although its nature is not known. The label acquired by platelets during hemopoiesis is, at least in part, in the form of a sulfated mucopolysaccharide and appears to undergo little turnover in circulating platelets.
Stimulation of peptide synthesis in adipose tissue by insulin without glucose
Authors: Krahl M. E.
Published: December 2017

The ability of insulin to stimulate incorporation of histidine-2(ring)-C14 into rat epididymal adipose tissue protein in absence of added glucose was investigated. Insulin alone was without effect, but a significant insulin stimulation was obtained when 10, 20, or 40 mm sodium pyruvate was added to the Krebs-bicarbonate incubation medium. This stimulation was not dependent on traces of glucose, since the pyruvate contained no detectable glucose; moreover, the concentration of glucose required to support the insulin stimulation was found to be not markedly different from that for pyruvate. The conclusion is that the effect of insulin on protein synthesis in adipose tissue is not dependent on any effect it may have on glucose entry.
Polycythemia in rats following restricted food intake
Authors: Wohl Herbert , Merskey Clarence
Published: December 2017

Rats were divided into two groups such that mean weight and hemoglobin and hematocrit levels were not significantly different. One group (controls) was then fed a normal chow ad libitum. The other group was fed 6 g daily (30% of normal intake) for 2 weeks. The hemoglobin levels of rats fed the restricted diet rose 1.4–3.5 g/100 ml and hematocrit level rose 2–6%. At the end of 2 weeks total red cell mass (Cr51) was 5.5–6.0 ml in the underfed groups compared with 6.8 ml in the control group. Body weight fell proportionally more than did red cell mass, elevating the calculated red cell mass per unit body weight. Serum osmolality and K+ were not significantly different from control values, and there was a slightly higher serum Na+ and Cl– in the restricted diet group. It is concluded that restriction of food intake produced a relative polycythemia. At the end of 2 weeks of restriction an isosmotic reduction in plasma volume was present.
Screen filtration pressure of homologous and heterologous blood and electroencephalogram
Authors: Hirsch Hans , Swank Roy L. , Breuer Marianne , Hissen Wolfgang
Published: December 2017

The character and duration of electrical activity arising from a completely isolated cat's head was dependent upon the screen filtration pressure (SFP) of the heparinized oxygenated blood with which it was perfused. If the SFP was above normal the amplitude and frequency of the EEG first decreased, then the brain waves disappeared. The duration of time from the beginning of perfusion until these changes in the EEG occurred was inversely related to the SFP of the perfused blood. Also, the perfusion rate was inversely related to the SFP provided the perfusion pressure remained the same. It is believed that the increase in SFP and changes in EEG and blood flow were due to the presence in the blood of aggregates of blood cells (platelets and leucocytes) which obstructed the brain capillaries. It would appear that heterologous (dog) as well as homologous (cat) blood can be effectively used to perfuse the isolated cat's head provided the blood has a normal SFP. In practice, this was made possible by filtering the blood continuously through Pyrex glass wool.
Reflex responses to stimulation of baroreceptors in the right subclavian artery
Authors: Okada Hiromasa
Published: December 2017

The effect of stimulation of the baroreceptors of the right subclavian artery upon the efferent impulse activity of the cardioregulatory and abdominal sympathetic nerves was investigated in decerebrate cats and anesthetized dogs. Increase in the pressure in the isolated and perfused right subclavian-carotid arterial segment diminished or abolished the impulse activity in the cardiac and abdominal sympathetic nerves. Simultaneously there was an increase of impulse activity in the cardiac vagus. No appreciable change of impulse activity in the long ciliary nerve was noticed. Impulse activity in the cardiac vagus nerve was found to be predominant during expiration both in decerebrated and anesthetized dogs with bilateral occlusion of the common carotid arteries.
Cerebral adenosine triphosphate in rats with ammonia-induced coma
Authors: Schenker Steven , Mendelson Jack H.
Published: December 2017

Current hypotheses of the pathogenesis of ammonia intoxication postulate an intracerebral adenosine triphosphate (ATP) depletion as a result of: 1) decreased ATP synthesis due to inhibitory effect of ammonia on cerebral oxidative metabolism; and 2) increased ATP utilization during ammonia detoxication. In this investigation net cerebral cortical ATP concentration of ammonium acetate-injected precomatose and comatose, as well as control rats, was determined using the luciferin-luciferase-luminescence assay. The normal mean cerebral cortical ATP level was 2.43 ± .50 µm/g of brain. No alteration from normal of cerebral cortical ATP was found in rats with ammonium acetate-induced precomatose and comatose states. These findings, which do not exclude ATP deficiency in some circumscribed vital cerebral site(s), indicate absence of generalized cerebral ATP depletion in experimental ammonia intoxication.
Prothrombin synthesis in the dog
Authors: Anderson Gordon F. , Barnhart Marion I.
Published: December 2017

Liver parenchymal cells were found to be the sites for production of prothrombin. Dogs were employed and their rate of prothrombin synthesis was modified as desired by giving either Coumadin or vitamin K1. The fluorescent antibody technique was found a valuable aid in evaluating liver cell function. Under normal conditions there is periodic synthesis of prothrombin with only 10% of the parenchymal cells actively participating at any one time. Prothrombin-deficient or normal dogs can be stimulated to more vigorous activity by giving vitamin K1. In such circumstances all the liver parenchymal cells were able to synthesize prothrombin. A regulatory mechanism promotes either synthesis, storage, or release of prothrombin by liver parenchymal cells. No other cell types of the liver, spleen, or bone marrow appeared capable of synthesizing prothrombin.
Reflex pulmonary vasoconstriction due to stimulation of the aortic body by nicotine
Authors: Stern Shlomo , Ferguson Richard E. , Rapaport Elliot
Published: December 2017

To study the hemodynamic effects of stimulation of the aortic and carotid body chemoreceptors, we injected 2.5– 20 µg/kg nicotine into the ascending aorta of anesthetized, artificially ventilated open-chest dogs. Pressures in the pulmonary artery, left atrium, and systemic arteries, and the stroke output of the right ventricle were measured simultaneously. Pulmonary and systemic vascular resistances (PVR, SVR) were calculated. Changes began 1.5–3.0 sec after the injection; the following two 5-sec periods were compared to a 5-sec control period immediately preceding injection. The injection of nicotine was followed by a significant reflex rise in PVR; the sensory receptors for the reflex were aortic chemoreceptors and the efferent paths were sympathetic fibers. Similar effects were not elicited by stimulation of the carotid body. Bronchoconstriction, changes in bronchial flow, shifts of blood volume between the vascular beds, and liberation of catecholamine were excluded as factors in the PVR increase. Bradycardia, increased SVR, and decreased flow also occurred after combined stimulation of the aortic and carotid chemoreceptors; however, when bradycardia was prevented by atropinization, no significant change in flow occurred.
Mechanism of bronchoconstriction produced by thromboemboli in dogs
Authors: Thomas Duncan , Stein Myron , Tanabe Genzo , Rege Vishram , Wessler Stanford
Published: December 2017

In 19 dogs, the release of autologous venous thrombi to the lungs resulted in bronchoconstriction, with a rapid rise in the total lung resistance and a fall in the lung compliance. The respiratory rate and arterial-alveolar CO2 tension difference also increased significantly. The administration of either heparin or a 5-HT antagonist completely prevented the bronchoconstriction, without affecting either the respiratory rate or arterial-alveolar CO2 tension difference. Bronchoconstriction resulting from direct 5-HT infusion was not prevented by heparin, nor was the contraction of an isolated rat uterus in response to 5-HT. However, 5-HT was not released from canine platelets by thrombin in vitro, in the presence of heparin. The evidence suggests that bronchoconstriction in the dog due to autologous pulmonary emboli results from thrombin-induced 5-HT release, and that heparin, by its antithrombin action, prevents this release.
Carnitine effects on palmitate-1-C14 conversion to CO2 and glycerides by various tissues
Authors: Fritz Irving B.
Published: December 2017

Carnitine increased oxidation of palmitate-1-C14 by rat heart and liver preparations, but decreased palmitate incorporation into glycerides. To determine which of the effects was derivative and which was primary, experiments were repeated using tissues whose rates of fatty acid oxidation had been depressed by Amytal poisoning. Under these conditions, carnitine inhibition of fatty acid conversion to glycerides was abolished. Similarly, low concentrations of carnitine were found to enhance palmitate oxidation without influencing palmitate esterification. Isolated liver microsomes which synthesized glycerides without oxidizing fatty acids showed no response to carnitine under all conditions tried. The inability of carnitine to alter glyceride formation in experiments described may signify that acyl-CoA generation from CoA and acylcarnitine is specifically directed toward the fatty acid oxidase system rather than to glyceride synthesis. It was also shown that, under conditions optimal for demonstration of carnitine augmentation of fatty acid oxidation by rat heart preparations, carnitine increased palmitate oxidation by a variety of other tissue homogenate preparations.
Hormonal effects on metabolism and distribution of plasma albumin in the dog
Authors: Takeda Y.
Published: December 2017

The effects of growth hormone, cortisone, and thyroxine on the metabolism and distribution of plasma albumin were studied, using albumin-I131 as a tracer. Growth hormone did not significantly change the synthetic and catabolic rates of albumin in the steady state reached 7 days after the start of the hormone injection, but the increased body weight and total exchangeable albumin in the first 7 days indicate either increased synthetic or decreased catabolic rate of albumin during that period. Cortisone immediately increased the catabolic rate of plasma albumin to a level 28% above the control value, and this level was maintained during the entire experimental period, but the synthetic rate slowly rose to equal the raised catabolic rate by about the 7th day. Thyroxine showed effects similar to those observed with cortisone. It was also shown that all the hormones stimulated the rate of transcapillary transport of albumin and significantly altered the passage time distribution of albumin flux through the interstitial fluids.
Hormonal effects on distribution and excretion of iodide-I131 in the dog
Authors: Takeda Y.
Published: December 2017

Studies of the kinetics of iodide-I131 given intravenously to control dogs and dogs receiving growth hormone, cortisone, and thyroxine showed that growth hormone and cortisone increased, whereas thyroxine decreased, the rate of urinary excretion of I131. By applying the kinetic analysis described previously it was found that the rates of distribution and excretion of iodide-I131 in the control and hormonal experiments were sufficiently rapid not to affect the interpretation of metabolic studies made with albumin-I131 in the dog. These results permit improved and more accurate estimates of the metabolism and distribution of plasma albumin in control dogs and dogs treated with the hormones.
Characteristic force-velocity equation of rat heart muscle
Authors: Ullrick William C.
Published: December 2017

Shortening velocities were measured for in vitro rat left ventricular trabeculae carneae preparations stimulated to contract isotonically with different loads, and at temperatures from 20 C to 35 C. The data obtained were used to derive the heat of shortening constant, a, the velocity constant, b, and the maximum isometric tetanic tension term, P0, of the characteristic force-velocity equation. The study showed that the derived constants a and P0 statistically did not vary with temperature, but that the velocity constant b increased linearly as temperature increased. Differences between cardiac and skeletal muscle are discussed.
Urea transport across dog intestinal mucosa in vitro
Authors: Hakim A. A. , Lifson Nathan
Published: December 2017

Mucosal membranes from the small intestine of the dog were stripped and mounted for study between two bathing fluids, as previously described. The relationship between urea and water transport, including uphill movement of urea in the direction of water flow, was that expected from a combination of bulk flow and diffusion. If sieving was present, it was minor. Results for downhill movement of D2O, the isotopic water treated as a solute, were comparable to those for urea.
Quantitative assay and disappearance rate of circulating renin
Authors: Schaechtelin G. , Regoli D. , Gross F.
Published: December 2017

In isovolemic cross-circulation experiments, a nephrectomized donor rat, into which various doses of hog renin were injected, was connected to a nephrectomized indicator rat. The blood pressure increase thus produced in the indicator rat was compared with the blood pressure response obtained during cross circulation using either intact normotensive or renal hypertensive rats as donor animals. An exponential dose-response relationship was found between hog renin injected into a nephrectomized donor and the blood pressure increase of the indicator rat. Using the cross-circulation technique, the disappearance rate of endogenous reninlike material in the blood of donor animals and of exogenous renin injected into nephrectomized donor animals was examined. If an intact normotensive animal or a unilaterally nephrectomized hypertensive animal is totally nephrectomized, reninlike material disappears from the blood within 1 hr. In renal hypertensive rats with an untouched contralateral kidney which have a higher concentration of reninlike material in the blood, it takes about twice the normal time until reninlike material disappears from the blood after nephrectomy. The increased and prolonged blood pressure response of the nephrectomized animal to renin is not connected with a prolonged persistence of renin in the blood.
Initial distribution and rate of uptake of sulfobromophthalein in the liver
Authors: Goresky Carl A.
Published: December 2017

Multiple indicator-dilution studies of the hepatic uptake of sulfobromophthalein in the dog were carried out using a single intraportal injection of labeled red cells, labeled albumin, and sulfobromophthalein. Analysis of the dilution curves was carried out using a graphical method based upon a flow-limited linear two-compartment mathematical model system in which the rate of sulfobromophthalein removal was assumed proportional to the product of the concentration in and the volume of the extravascular space. This analysis permitted direct estimation of both the volume of the extravascular space initially accessible to sulfobromophthalein and the rate constant for removal. Sulfobromophthalein was found to be distributed into an extravascular space equivalent in volume to that accessible to albumin. Diminution of the rate constant for removal occurred with increasing dosage, indicating saturation. The initial maximal transport capacity and plasma concentration leading to half maximal initial velocity of transport were estimated. The initial maximal transport capacity is much larger than the maximal steady-state capacity for excretion into bile.
Failure to demonstrate vasopressor material in salt hypertensive rats
Authors: Koletsky Simon , Pritchard Walter H.
Published: December 2017

Rats with acute or chronic salt hypertension were assayed for the presence of circulating vasopressor material. The technique consisted of transferring blood from the hypertensive rats to normal recipient rats and measuring the rise in blood pressure of the recipients. The blood of salt hypertensive animals proved to be uniformly devoid of vasopressor activity during the entire course of hypertension. The negative assays matched those obtained with normotensive blood from sham-operated rats and were in sharp contrast to the positive assays in early renal hypertension. The results indicate that salt hypertension is not mediated through a humoral pressor mechanism.
Analysis of vascular responses in the spleen
Authors: Boatman Dennis L. , Brody Michael J.
Published: December 2017

Canine spleens were isolated and perfused at constant flow with blood from a femoral artery. Perfusion pressure, small vein pressure, tissue cannula pressure, organ weight, and capsular tension were monitored continuously. Splenic nerve stimulation and epinephrine elevated total resistance and increased small vein pressure more than tissue cannula pressure Evidence was provided which demonstrated that the venous pressure increment resulted primarily from active contraction of the splenic veins. Norepinephrine produced equivalent changes in total resistance but was significantly less effective than nerve stimulation and epinephrine, both in raising venous pressure and contracting the splenic capsule. Acetylcholine decreased total resistance, whereas venous pressure was increased by a passive mechanism. The effect of synthetic angiotensin was restricted to contraction of the splenic arterial segments. The highly distensible nature of the spleen was illustrated in experiments where total occlusion of venous flow had only minor effects upon the resistance to arterial inflow. Retrograde perfusion through the splenic vein failed to result in flow out of the splenic artery, indicating that valves or a valvelike mechanism are located at some presinusoidal site along the vascular tree.
Effects of left stellate ganglion stimulation on left ventricular synchrony in dogs
Authors: Osadjan Charles E. , Randall Walter C.
Published: December 2017

The cardiac response to excitation via the sympathetics has led to the inference that improved synchrony of contraction in the ventricular musculature is important to augmented performance. Pin electrodes and strain-gauge arches were fixed to several segments of the left ventricle, and the precise sequence of electrical excitation and mechanical shortening of the septum and epicardial segments of the apex and base compared during control periods and during electrical stimulation of the left stellate ganglion. During stimulation, augmentation in force of contraction was recorded from all segments, including the interventricular septum. In controls, one-half showed initial shortening at the apex and one-half at the base. During stimulation of the stellate, the base contracted first, and the electromechanical coupling time decreased significantly. The septum shortened last in all circumstances. The time interval between the first and the last segment to shorten decreased during stimulation, indicating increased synchrony of contraction. This undoubtedly contributes to the more rapid rise phase of the ventricular pressure pulse during sympathetic stimulation.
Polysaccharide effects simulating hypersensitivity responses in the rabbit
Authors: Cohen Sheldon G. , Sapp Theresa M.
Published: December 2017

The intravenous administration of specific polysaccharides (glycogen, amylodextrin, amylopectin) to rabbits resulted in changes in levels of circulating eosinophils and heterophil (polymorphonuclear) leukocytes over a 24-hr period. These were associated with the development of corresponding cell infiltrations within pulmonary vascular and perivascular tissue and spleen and less consistently in liver and myocardium. Features of hematologic and tissue inflammatory cell responses resembled those effected by antigen-antibody union. However, these developments could not be related to the possible participation of the polysaccharide in immune reactions by reason of natural serum antibody content: a) preformed precipitins to corresponding administered polysaccharides, or b) isoagglutinins to related blood group substance. Neither hypersensitivity nor polysaccharide effects were prevented by chemical antagonists of histamine release.
Isolation and assay of dipalmityl lecithin in lung extracts
Authors: Brown Elwyn S.
Published: December 2017

Lung extracts were obtained by either mincing the lungs in saline or by washing the lung with saline through the trachea. The surface tensions of the extracts on compression to 10% of the original area in a surface balance decreased to 7.5 ± 2.1 dynes/cm for rabbits, 10.0 ± 1.8 dynes/cm for dogs, and 6.8 ± 3.8 dynes/cm for man. The surface-active material in the extracts was completely precipitated with trichloroacetic acid. Ethyl or methyl alcohol extracted the activity from the precipitate. By concentrating and chilling the alcohol extract, a very surface-active white precipitate was obtained which was identified as dipalmityl phosphatidyl choline by melting point, chemical analysis, and paper chromatography. Cadmium chloride also precipitated a surface-active complex from the alcohol extract which was identified chemically as dipalmityl phosphatidyl choline. The quantity of hydrolecithin extracted from the lungs was 0.09–0.18% on a wet weight basis. No evidence of the presence of sphingomyelin or other surface-active phospholipid was obtained.
Effects of exercise and food restriction on serum cholesterol and liver lipids
Authors: Jones Evelyn M. , Montoye Henry J. , Johnson Perry B. , John Martin Martin Sister M. , Van Huss Wayne D. , Cederquist Dena
Published: December 2017

The effect of 15 weeks of regular, vigorous exercise (swimming) on serum and hepatic cholesterol in rats was studied. The effect of exercise on body composition and the interrelation of body composition and serum and hepatic cholesterol was also investigated. Caloric restriction without exercise was imposed on another group of rats in an effort to produce animals with body composition similar to those subjected to exercise. The calorie-restricted animals were retarded in growth as evidenced by lower ash weight but their body composition on a percentage basis was almost identical to the ad libitum fed animals who were not exercised. It was concluded that: 1) Exercise was effective in preventing most of the increase in body fatness and serum cholesterol concentration associated with an increase in age. 2) Neither total nor free cholesterol concentration in the liver was affected by exercise, but the concentration of total hepatic lipids was reduced. 3) Body fatness, serum cholesterol, and concentration of total hepatic lipids were all positively correlated with each other and inversely related to weight of the adrenal glands in the animals.
Effect of osmolality on glucose metabolism in rabbit kidney cortex and medulla in vitro
Authors: Lee James B. , Vance Vernon K. , Cahill George F.
Published: December 2017

Slices of rabbit kidney cortex and medulla were incubated aerobically in media of varying osmotic concentrations. When medium osmolality was reduced below 280–300 mosmoles/kg H2O, by means of decreased sodium chloride and sucrose concentrations, there was an osmotically determined increase in cortical glucose utilization and oxidation, lactate production, and slice weight. Between 280 and 300 mosmoles/kg H2O maximal cortical slice weight loss and inhibition of glucose metabolism occurred, with little further change when medium osmolality was increased to 415 mosmoles/kg H2O. With urea, slice weight and relatively maximal glucose metabolism were maintained at all medium osmotic concentrations between 67 and 548 mosmoles/kg H2O. In contrast, slices of kidney medulla revealed a capacity for extensive glucose oxidation in hyperosmotic media (1,066 mosmoles/kg H2O), while maximal lactate production occurred in hypoosmotic media (67 mosmoles/kg H2O). The findings are interpreted as suggestive of responsiveness of cortical and medullary intermediary metabolism to changes in the "effective" extracellular-to-intracellular osmotic gradient.
Rapid passage of organic anions into human red cells
Authors: Schanker Lewis S. , Johnson Jean M. , Jeffrey John J.
Published: December 2017

The rates at which organic acids penetrate the human red cell suspended in Tyrode's solution are roughly related to the lipid-to-water partition coefficients of the compounds measured at pH 7.4 using chloroform as a lipidlike solvent. Phenol, sulfadiazine, sulfathiazole, 5-nitrosalicylic acid, p-aminobenzoic acid, and salicylic acid, compounds of relatively high lipid solubility, become equilibrated between the cells and suspending medium in less than 5 min. Phenol red, sulfosalicylic acid, sulfanilic acid, hippuric acid, and p-aminohippuric acid, compounds of lower lipid solubility, become equilibrated more slowly, the times ranging from 1 to more than 7 hr. Measurements of the intracellular binding of phenol red and sulfosalicylic acid indicate that the unbound anions are distributed across the cell membrane according to a Donnan equilibrium. Organic anions enter the cell much more rapidly than do organic cations of a similar low lipid solubility. The preferential permeability toward anions is considered in terms of various models of the cell membrane, and a mechanism for anion penetration is suggested.