bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of choline and other quaternary ammonium compounds on Na movements in frog skin
Authors: Macey Robert I. , Koblick Daniel C.
Published: December 2017

Effects of choline on short-circuit current and radioactive sodium flux were measured in isolated frog skins. Replacement of control ions (K or Mg) by choline in the outside solution increased the short-circuit current and inward Na flux. When K was the control ion, the average increase in short-circuit current was 52%; with Mg, it was 36%. In both cases, the increase in inward Na flux accounted for about 75% of the short-circuit current increase, while passive choline movement possibly accounted for the remainder. Similar results were obtained using tetramethylammonium and tetraethylammonium in place of choline. One implication of these results is that studies in which choline is used as an inert substitute for Na must be interpreted with caution.
Effect of nicotine on cardiac muscle contractions and radiocalcium movement
Authors: Nayler Winifred G.
Published: December 2017

Nicotine, 0.01–0.1 mm, evoked a positive inotropic response and abolished the "staircase" and poststimulation potentiation in toad ventricular muscle; 0.2 mm nicotine caused the development of contracture, whether or not extracellular Ca++ was present; and 1.0 mm nicotine enhanced the uptake and release of Ca45 from the muscle. It seems probable that the effect of nicotine on the contractile response of cardiac muscle can be related to the mobilization of Ca++.
Effects of arterial hypoxia on the heart and circulation: an integrative study
Authors: Cross Cecil E. , Rieben P. Andre , Barron Charles I. , Salisbury Peter F.
Published: December 2017

An integrative series of investigations progressed from simplified systems, where cause-and-effect relations were relatively clear, to the virtually intact animal with separately perfused carotid arteries. Arterial pO2 below 40 mm Hg (about 75% oxygen saturation) caused edema of the heart muscle; however, the contractile strength and performance of isolated hearts were compromised severely only when the arterial pO2 had fallen below 15 mm Hg (about 25% saturation). The ‘acute circulatory crisis" which is known to occur when the arterial oxygen saturation falls below 80% was not caused by weakness of the heart muscle but by reflexes from the carotid artery territory: even when the oxygen saturation of systemic arterial blood had fallen as low as 50% this did not cause heart failure as long as the carotids were perfused with blood of normal pO2. Severe heart failure occurred when the blood in the carotid arteries was moderately hypoxic (pO2 below 50, sat. below 80%) while the rest of the circulation was fully oxygenated.
Pyruvate metabolism in the perfused rat heart
Authors: Evans John R. , Opie Lionel H. , Renold Albert E.
Published: December 2017

The metabolism of C14-labeled pyruvate in the isolated heart was studied in a closed recirculation system. Decarboxylation was the major fate of pyruvate-1-C14 and increased according to the concentration of pyruvate in the perfusion fluid. Lactate formation accounted for most of the remainder of the pyruvate-1-C14 uptake and negligible radioactivity was recovered in glycogen or tissue lipid. Comparison of the metabolism of pyruvate-1-C14 and pyruvate-2-C14 suggested that in the presence of fatty acid, oxidative decarboxylation and condensation to citric acid continued to be the principal route of entry of pyruvate into the tricarboxylic acid cycle although dilution or diversion of decarboxylated metabolites of pyruvate to nonoxidative fates was increased. Pyruvate in 5- and 10-mm concentrations reduced oxidation of palmitate-C14 and increased incorporation of palmitate into tissue lipid, specifically tissue triglyceride. The uptake and decarboxylation of pyruvate-1-C14 were less in hearts from rats fasted overnight than in hearts from rats fed ad libitum. It is proposed that oxidation of fatty acid may be the mechanism responsible for decreased utilization of pyruvate in the fasting state and other conditions in which fatty acid is the principal myocardial fuel.
Movement of fluid, albumin, and globulins with overtransfusion and hemorrhage
Authors: Deavers S. , Smith E. L. , Huggins R. A.
Published: December 2017

Two groups of 18 morphine-pentobarbitalized dogs were used for the experiments. Determinations of plasma volume and protein concentration were made before and after the experimental procedures. The first group was bled to a mean arterial pressure of 35 mm Hg. During an average bleeding time of 74 min in which the dogs bled 48% of their circulating plasma and 47% of their total protein, 29% of the plasma and 14% of the protein removed has been replaced from extravascular sources. Those dogs that bled for the longest time gained the greatest amount of fluid and protein. Globulins comprised 74% of the protein mobilized. The second group of dogs was overtransfused with a mean volume of 85 ml/kg of whole blood. Thirty minutes after the transfusion, 20 ml/kg of plasma and 0.53 g/kg of protein escaped from the vascular system. No correlation was found between the rate of infusion and the rate of fluid and protein loss. Seventy per cent of the total protein leaving the circulation was albumin.
Effects of hypothalamic estrogen implants on pituitary LH and prolactin in rabbits
Authors: Kanematsu Shigeto , Sawyer Charles H.
Published: December 2017

A minute amount of estradiol benzoate was implanted into the posterior median eminence-basal tuberal region of the hypothalamus or hypophysis in female rabbits. Pituitary LH was measured by the ovarian ascorbic acid depletion method. Prolactin assays were performed on the same hypophyses by the intradermal pigeon crop sac method. Pituitary LH content was 0.47 µg/mg wet wt. following implantation of estrogen into parts of the brain other than the posterior median eminence-basal tuberal area. However, when estrogen was implanted into the posterior median eminence-basal tuberal area the pituitary LH content decreased markedly to less than 0.05 µg/mg and this decline was associated with ovarian atrophy. The prolactin content was significantly elevated ( P < 0.01) but the mammary glands were not activated. Estrogen implantation into the adenohypophysis appeared to cause release of prolactin but failed to affect the LH content (0.50 µg/mg) or to induce ovarian atrophy. The results indicate that estrogen acts on the posterior median eminence-basal tuberal area to stimulate production but not release of prolactin and, simultaneously, to inhibit synthesis of LH.
Maintenance of adrenalectomized rats through conception, pregnancy, and lactation
Authors: Anderson R. R. , Turner C. W.
Published: December 2017

Maintenance of the reproductive cycle through conception, pregnancy, and lactation was attempted in 231 adrenalectomized rats by subcutaneous replacement therapy with cortisol acetate and/or deoxycorticosterone acetate (DCA). The combination of 100 µg cortisol and 50 µg DCA was not ample for pregnancy maintenance. Saline drinking water (1% NaCl) was insufficient therapy to support pregnancy. Cortisol at 150 or 250 µg and DCA at 250 µg enabled conception and maintenance of pregnancy to occur at 75% and lactation maintenance at 43% of the normal incidence. DCA at 250 µg/day maintained adrenalectomized rats in excellent condition and permitted conception and pregnancy to proceed at a rate equal to the normal control group; however, DCA did not support lactation without the addition of the glucocorticoid. Deoxyribonucleic acid content of the mammary glands was higher in groups receiving cortisol than in the group maintained on DCA.
Hepatic metabolic and vascular responses to epinephrine: a unifying hypothesis
Authors: Craig Albert B. , Honig Carl R.
Published: December 2017

With the aid of rapid sampling techniques and measurements of phasic blood flow the complete time courses of epinephrine-induced hyperkalemia and hyperglycemia were delineated. The initial changes in transhepatic K and glucose balances and in the hepatic circulation were also determined. Efflux of K is coincident with the arrival of epinephrine at the liver, and is synchronous with or slightly earlier than glucose efflux. This implies that K and glucose release reflect a common epinephrine-sensitive process. Hyperkalemia is a transient phenomenon and is not sustained by the continued presence of the hormone. K efflux is independent of the initial decreases in total hepatic blood flow and in tissue oxygen tension induced by the hormone. We conclude that epinephrine initiates a sequence of reactions leading to glycogen breakdown, one of which results in an incidental loss of K. A hypothesis is suggested which accounts for efflux of both K and glucose on the basis of a single intracellular process.
Transmembrane potentials of trypsin-dispersed chick heart cells cultured in vitro
Authors: Lehmkuhl D. , Sperelakis Nick
Published: December 2017

Hearts (ventricles) from 6- to 8-day-old chick embryos were cultured 1–7 days. Single cells reassembled into various communities of cells which usually contracted synchronously. Many cells were spontaneously active; quiescent cells could be driven. The average magnitude of the action potentials after microelectrode sealing was 71.2 ± 1.5 mv (range of 40–108 mv) and that of the resting potentials 59.0 ± 1.2 mv (range of 40–84 mv). Maximum velocity of depolarization varied between 1–5 v/sec and positive afterpotentials of 6–10 mv were often found. The duration of the action potential varied between 150–500 msec. Plateaus were observed in only a few of the cells; often a second component appeared on the repolarization phase of the spike. Many cells had pacemaker potentials of about 10 mv. However, even though pacemaker potentials were present, many cells were fired by transmission of excitation from neighboring cells; in such cases, a prepotential was generally observed as a step in the rising phase of the action potential. The data from trypsin-dispersed cells were compared with those of nondispersed clumps and with noncultured intact embryonic hearts. The results indicate that the electrophysiological properties of trypsin-dispersed cultured myocardial cells are similar to those of cells in intact embryonic or adult hearts.
Effect of pacemaker location on cardiac function in complete A-V heart block
Authors: Fletcher Fred W. , Theilen Ernest O. , Lawrence Montague S. , Evans John W.
Published: December 2017

These experiments were designed to determine if the location of ectopic ventricular stimulation influences ventricular performance. Heart block was produced in dogs by ligating the A-V bundle. Small bipolar electrodes were implanted in the apex, high lateral wall, and posterior septal region in six dogs. Several days after recovery dye dilution cardiac outputs, femoral arterial, and right atrial pressures were measured while stimulating from each of the three sites at varying rates between 60 and 240 beats/min. Mean cardiac outputs from stimulation at each of the three sites were similar and their 95% confidence intervals overlapped. Mean systemic pressure did not change significantly with frequency or location of ventricular stimulation. The experiments suggest that the pathway of ventricular activation does not affect ventricular function in complete heart block.
Antidiuretic response to electrical stimulation in brain stem of the monkey
Authors: Hayward James N. , Smith Wilbur K.
Published: December 2017

Antidiuretic hormone release was produced in conscious monkeys by electrical excitation of certain regions in the brain stem. The experimental design allowed repeated control and test observations in the same animal over a period of months. Alterations in free water clearance and urine osmolality resulted from electrical stimulation of the hypothalamus, the mesencephalic reticular formation, the ventral tegmental area of Tsai, and the periaqueductal gray substance. A similar drop in free water clearance and a rise in urine osmolality without a change in glomerular filtration rate was observed in the same animals after intravenous infusion of vasopressin. No significant changes in free water clearance or in urine osmolality were observed during the taking of blood samples, the infusion of isotonic saline or of 5% dextrose, or as a result of stimulation of the dorsolateral hypothalamus, thalamus, red nucleus, tectum, pons, and the optic chiasm.
Intestinal and hepatic transport of cholate and organic dyes
Authors: Tidball C. S.
Published: December 2017

The 3-hr cumulative biliary appearance of a bile salt and three representative organic dyes was studied in rats anesthetized with sodium pentobarbital. The substances were administered in one of the following locations: a branch of the portal vein, a 20-cm isolated loop of proximal jejunum, or a similar loop of distal ileum. Average biliary recoveries of 10 mg cholate, bromsulfonphthalein, diiodotetrachlorofluorescein (rose bengal) or phenolsulfonphthalein (phenol red) introduced slowly into the portal circulation were 97, 97, 68, and 23%, respectively. The respective recoveries of 30-mg quantities of these four substances placed in the intestinal loops were 43, 5, 2, and 1% proximally and 90, 5, 5, and 0.4% distally. These observations confirm the presence of a specific intestinal transport mechanism for cholate with maximal activity in the distal ileum. However, the three representative organic dyes are shown not to be carried by the intestinal bile salt transport mechanism and their movement from gut lumen to portal vein blood should be ascribed to a passive process.
Changes in elasticity of pulmonary reflexogenic area with sympathetic activity
Authors: Bevan John A. , Johnson R. C. , Verity M. Anthony
Published: December 2017

The isolated rabbit sympathetic nerve-pulmonary artery preparation has been shown to be taken from a part of the pulmonary artery which contains a high concentration of adventitial sensory endings resembling those in the carotid sinus and aortic depressor area. Using this preparation the static bulk modulus of elasticity has been measured under a variety of circumstances. Sympathetic nerve stimulation, increased potassium ion concentration, and l-norepinephrine addition decreased the unstretched circumference of the artery, with increasing strain, increased and then decreased the elastic modulus of the arterial wall, and decreased the change in elastic modulus for any proportionate increase in circumference. Sodium nitrite had opposite actions. Angiotensin and pH changes between 7.0 and 8.1 had no effect on these measurements. A possible cause for some of the divergent conclusions found in the literature, and the relation of these experimental findings to the afferent activity of associated pressoreceptors is discussed.
Coronary sinus drainage and measurement of left coronary artery flow in the dog
Authors: Friesinger G. C. , Schaefer J. , Gaertner R. A. , Ross R. S.
Published: December 2017

The indicator-dilution principle has been employed to study coronary blood flow and the venous drainage into the coronary sinus ( CS) in the dog. Nine open-chest dogs were prepared to allow separate perfusion and flow measurement of the right and left coronary arteries ( RCAand LCA) as well as simultaneous sampling at two sites in the CS. By injecting indicator at various sites in the arterial tree, it has been demonstrated that the posterior circumflex artery drains chiefly to the CS near the CS ostium; the left anterior descending drains chiefly to the area of the CS far upstream from the CS ostium, and the RCA does not drain to the CS. These drainage data have been used to help determine the adequacy of mixing of dye and blood, and to measure LCA flow. Adequate mixing of dye and blood was frequently achieved by the criteria established, but LCA flow was accurately measured with only a minority of injections. It is likely that pecularities of the anatomy of the coronary vascular bed account for the discrepancies.
Effect of plasmin on fibrinogen and fibrin
Authors: Gajewski Jerzy , Alexander Benjamin
Published: December 2017

The interactions of plasmin with I131-labeled fibrinogen and fibrin were compared. These substrates appear to be equally susceptible to the enzyme, as judged from the amount of trichloroacetic acid nonprecipitable material resulting from the interaction. The velocity of the interactions appears different when material was subsequently recovered by dilution of the reaction mixture with water or with physiological saline. It is possible that plasmin, before digesting fibrinogen, affects its clottability adversely.
Action potentials of guinea pig atria under conditions which alter contraction
Authors: Sleator William , Furchgott Robert F. , Gubareff Taisija De , Krespi Vivian
Published: December 2017

Simultaneous recordings were made of action potential ( AP) and contractile strength ( CS) of electrically driven isolated left atria of guinea pigs at 25–27 C under various experimental conditions which alter CS. Reduction of CS produced by decreasing frequency from 1/sec to 0.1/sec, or by spontaneous failure, was associated with only small changes, if any, in AP configuration. The increased CS produced by strophanthin-K or high calcium was associated with shortening of the AP plateau duration; treatment with ryanodine increased AP plateau duration, and decreased CS. The first beat following a 3- to 10-sec rest interval (postrest ( PR) beat) exhibited greater CS, and an AP with shorter plateau and more pronounced "tailing off" than steady-state controls. With high calcium or strophanthin present, PR beats and steady-state beats were nearly identical in both CS and AP. After ryanodine, PR beats were markedly reduced in CS and had prolonged AP plateaus; these changes could be reversed by high calcium or strophanthin. A hypothesis is introduced which accounts for changes in CS under these conditions.
Interrelationships between diet and weight gain in rats with portacaval shunts
Authors: Masland William S.
Published: December 2017

Rate of weight gain and daily food intake, as well as fasting colon weight, liver weight, and arterial blood ammonia levels, were measured in rats with end-to-side portacaval anastomoses and their sham-operated, paired controls. The diets provided were regular chow and special, low-residue feed with increased amounts of protein, fat, or carbohydrate. The chow-fed, operated group gained weight at a significantly slower rate than their paired controls which was the only significant intragroup difference. The special-diet, operated groups gained significantly slower than the shams when the data from these groups were pooled, obliterating the dietary distinction. This singularity of the chow-fed group was accompanied by a very much heavier colon in both operated and control categories than that of animals receiving low-residue feed. Liver weights were lower and arterial ammonia levels higher in animals with shunts. The significance of the greater colon weight and lower rate of weight gain in fistulated animals receiving regular chow is discussed in the context of symbiotic relations between gastrointestinal flora and host.
Antihemophilic factor in cross-circulated normal and hemophilic dogs
Authors: Weaver R. A. , Price R. E. , Langdell R. D.
Published: December 2017

The technique of cross circulation was used to study antihemophilic factor ( AHF) in normal and hemophilic dogs. Following cross circulation of 60 min, the plasma AHF of the hemophilic animals had increased to about 50% of the normal level. This increase was not accompanied by a corresponding decrease in the AHF in the plasma of the normal dog. In other experiments, splenectomized normal dogs were cross circulated with hemophilic dogs. Without a spleen, the normal dog was unable to maintain its plasma AHF during the shunting procedure. These studies indicate that the spleen is important in the homeostasis of antihemophilic factor.
Utilization of fatty acids by rat liver slices as a function of medium concentration
Authors: Rose Herbert , Vaughan Martha , Steinberg Daniel
Published: December 2017

The rate of incorporation of palmitate-1-C14 into neutral lipids and phospholipids of rat liver slices in vitro and its conversion to C14O2 were shown to increase markedly as the free fatty acid (FFA) concentration of the medium was increased. Incorporation into lipids and conversion to C14O2 proceeded linearly with time over 60 min. The incorporation of glycerol-1,3-C14 into neutral lipids also increased as the FFA concentration of the medium was increased but incorporation into phospholipids was unchanged. It is concluded that high FFA concentrations cause a true increase in rate of neutral lipid synthesis by liver slices. The associated increase in incorporation of labeled palmitate into phospholipids most likely reflects the higher specific radioactivity of the precursor pool of FFA and/or an exchange reaction rather than a true increase in net synthesis. A method for recovering tissue FFA quantitatively is described. Normal liver was found to contain 0.40–0.87 µEq FFA/g wet wt. The composition of this tissue FFA fraction is presented.
Metabolically induced permeability changes across mesothelium and endothelium
Authors: Cascarano Joseph , Rubin Arnold D. , Chick William L. , Zweifach Benjamin W.
Published: December 2017

The ability of mesothelial and endothelial membranes to influence solute passage into tissue preparations was investigated under in vitro conditions. It is possible by using the Warburg formula for the diffusion of solutes into tissue slices to calculate the concentration of solute bathing the subepithelial tissue when the depth of penetration and tissue activity are known. These conditions were met by selecting an electron acceptor with histochemical properties—the tetrazolium salt, 2- p-iodophenyl-3- p-nitrophenyl-5-phenyl tetrazolium chloride (INT). Quantitative studies with hemidiaphragm demonstrate that the concentration of INT which reaches the inner surface of the mesothelial layer is only 9% of that in the medium. Addition of a redox dye, phenazine methosulfate (PM), increases this value by 6.7 times. (Qualitatively similar results were obtained across mesothelial surfaces of liver and heart, as well as at endothelial surfaces of heart and carotid artery.) The ability of PM to increase permeability is counteracted by malate or succinate, and in turn restored when the latter is blocked with malonate. These results suggest that oxidative metabolism and adenosine triphosphate formation are intimately linked with this phenomenon.
Effect of acetylcholine, atropine, and physostigmine on renal function in the dog
Authors: Vander Arthur J.
Published: December 2017

Acetylcholine (1–500 µg/min), atropine (.002–.12 mg/kg min), or physostigmine (.01–.08 mg/min) was infused directly into the left renal artery of anesthetized dogs, and right and left kidney functions were compared. Acetylcholine produced variable changes in glomerular filtration rate (–30 to +55%), but always increased renal plasma flow (4–115%), sodium excretion (20–365 µm/min), potassium excretion (1–56 µm/min), and urine volume (.25–3.1 ml/min). Filtration fraction, urine osmolality, and medullary sodium concentration were always reduced. These changes could all be reversed or prevented by atropine. Stop-flow studies failed to demonstrate any distal tubular inhibition of sodium reabsorption by acetylcholine. Neither atropine nor physostigmine, when infused into the renal artery by itself, produced any changes in renal hemodynamics or electrolyte excretion. These data demonstrate that acetylcholine can decrease renal arteriolar resistance and inhibit tubular sodium reabsorption. They also provide indirect evidence which supports, but does not prove, the hypothesis that the kidney lacks parasympathetic innervation.
Effects of epinephrines on metabolism and contraction of cat papillary muscle
Authors: Lee Kwang Soo , Yu Dai Hyun
Published: December 2017

The change of metabolic state and contractility of heart induced by epinephrine and norepinephrine was studied in in vitro preparations of cat papillary muscle. The oxygen consumption, glycogen content, energy-rich phosphate content, and contractility of muscles were measured simultaneously whenever possible by techniques described previously. It was found that these amines did not change significantly the tissue contents of energy-rich phosphate compounds and glycogen in these conditions. The oxygen consumption and contractility of muscles were markedly influenced by the sympathomimetic amines. The change of metabolic efficiency as measured by the ratio, contractile tension : total Qo2, following the administration of these amines were dependent on the condition of heart muscles at the time of administration of these agents. Thus, when muscles were fresh, the metabolic efficiency was not significantly changed by the amines. However, when muscles were in the hypodynamic state, the amines were found to increase the metabolic efficiency of the heart muscle significantly. This suggests that the metabolic state of heart muscle should be taken into consideration whenever the influence of these sympathomimetic amines on the mechanical efficiency of heart is investigated.
Actomyosin content of rabbit heart ventricle
Authors: Inchiosa Mario A.
Published: December 2017

The requirements for quantitative extraction of rabbit cardiac actomyosin were investigated. Extraction of the tissue was carried out at pH 6.5. Under these conditions, precipitation of actomyosin from the soluble tissue extract showed a plateau between pH 6.9 and 7.1. This precipitation zone allowed excellent reproducibility in determination of actomyosin. Precipitation of actomyosin below pH 6.9 resulted in a sharp rise in nonactomyosin protein. The optimum range of ionic strength for quantitative precipitation of actomyosin was 0.03–0.10 (pH 6.9–7.0). The mean cardiac actomyosin content of the ventricles of young growing rabbits was 3.84% of the wet tissue weight and showed little variation among the animals. The cardiac actomyosin content of the ventricles of one dog studied by the same procedure was 5.36%.
Hemodynamic studies in normotensive and renal hypertensive chronic spinal dogs
Authors: Kaneko Yoshihiro , Page Irvine H. , McCubbin James W.
Published: December 2017

High spinal cord section caused reduction of stroke volume, cardiac output, aortic pressure, and increase in heart rate. Peripheral resistance was little changed. With time, arterial pressure and heart rate recovered to near control levels; stroke volume, cardiac output, and peripheral resistance tended to increase. Recovery of arterial pressure was due either to increase in peripheral resistance or increase in cardiac output. Elimination of essentially all efferent sympathetic activity caused little or no decrease in peripheral resistance; the small decrease in arterial pressure was accounted for by decrease in stroke volume and cardiac output. Atropine given well after recovery from operation increased heart rate, cardiac output, and aortic pressure while stroke volume decreased. The increase in blood pressure was due to increased cardiac output. Tetraethylammonium chloride given after atropine showed that cardiovascular denervation was essentially complete. Induction of experimental renal hypertension caused marked rise in peripheral resistance without change in stroke volume, heart rate, and cardiac output. Since cardiovascular denervation was complete, the hypertension was of humoral origin.
Myelopoiesis controlling agents in vitro
Authors: Gidáli Julia , Fehér Imre
Published: December 2017

The effect of sera from leukopenic and leukocytotic rabbits on normal rabbit bone marrow was studied in vitro. The rate of formate-C14 incorporation served for measuring the mitotic rate. Sera collected in the leukopenic phase or in the initial phase of leukocytosis, and incubated with normal bone marrow, were found to increase formate-C14 incorporation into cells significantly. On the other hand, sera collected at the peak of leukocytosis inhibited formate incorporation. Bone marrow from control rabbits incubated with sera from leukopenic and leukocytotic animals produced a characteristic change in the mitotic rate and in the ratio of myeloid precursors and mature myeloid elements. Kinetics of formate incorporation qualitatively agreed when bone marrow from leukopenic, leukocytotic, and control rabbits was incubated with the animals' own sera, or when bone marrow from control rabbits was incubated with leukopenic and leukocytotic sera, respectively. It may be assumed that the agents considered represent the humoral system maintaining the homeostasis of myeloid elements.
Effects of hyperthyroidism, epinephrine, and diet on heart lipoprotein lipase activity
Authors: Alousi Adawia A. , Mallov Samuel
Published: December 2017

Rats were fasted for several days, placed on diets high in carbohydrate, fat, or containing iodinated casein so as to produce hyperthyroidism, or were chronically injected with epinephrine. Lipoprotein lipase (LPL) activities of homogenates of the hearts of these animals were determined. Significant increases in LPL activity occurred in thyrotoxic animals, in rats receiving epinephrine injections chronically, or after prolonged fasting, while significant lowering of cardiac LPL activity was observed in rats on the high-carbohydrate or high-fat diets. Single doses of fat or single injections of epinephrine had no effect. Addition of epinephrine or of triiodothyronine to heart slices or homogenates in vitro caused no LPL increases. It is postulated that adaptive changes in cardiac LPL activity may occur in response to altered needs for utilization of fatty acids by the heart. Microsomal fractions of heart cells had the highest specific LPL activities, suggesting synthesis of the enzyme by these cellular components, or activity of the enzyme at the endoplasmic reticulum.
Lipolytic activity of rabbit aorta in vitro
Authors: Zsoldos S. J. , Heinemann H. O.
Published: December 2017

Lipolytic activity of rabbit aorta was demonstrated by perfusing the aorta in vitro with a 2% nonactivated triglyceride mixture in saline. The enzyme system responsible for the hydrolysis shares many but not all of the characteristics of a lipoprotein lipase.
Induction of gallstones in mice by feeding a cholesterol-cholic acid containing diet
Authors: Tepperman Jay , Caldwell Fred T. , Tepperman Helen M.
Published: December 2017

A high incidence of gallstones (90%) was observed during a study of the effect on the serum cholesterol of feeding an "atherogenic" diet to aurothioglucose- (ATG) injected obese and nonobese mice. In a second experiment (without ATG) groups of eight male and eight female mice were examined at monthly intervals after having been started on the stone-inducing diet. Gallstones began to appear after 2 months and the incidence increased to 75% after 8 months. Although there was no significant sex difference in cumulative incidence, stones tended to appear earlier in females. Serum cholesterol values were, however, significantly higher in males during most of the experiment. In a third experiment the following features of the original treatment were singly and systematically excluded from the regimens of groups of 20 male mice: 0.04% thiouracil in drinking water, high fat (30%), cholesterol (1%), cholic acid (0.5%), and low protein (11%). It was found that the combination of cholesterol and cholic acid was necessary and sufficient for stone formation if food intake remained adequate and liver function was unimpaired.
Bile flow rate and cholesterol content in mice fed a gallstone-inducing diet
Authors: Pedreira Frank , Tepperman Jay
Published: December 2017

Polyethylene tubing (i.d. 0.023 in.) was found to be of uniform bore. Therefore, it was possible to cannulate the gall bladder of anesthetized, common-duct-ligated mice and measure the rate of bile flow by marking off 10-min collection periods with thin black plastic tape. Rate of flow for each mouse (cm of tubing/10 min) was calculated from at least three consecutive 10-min flow periods during which the rate was maximal and linear. The rate for male chow-fed controls was 6.9 ± se 0.14. Mice fed a 1% cholesterol, 0.5% cholic acid (C-CA) gallstone-inducing diet for 2 days, 5 days, and 2 months showed rates of 10.6 ± 1.1, 15.5 ± 1.48, and 34.8 ± 3.8. The rate for females on chow and after 2 months on the C-CA diet was significantly higher than that for males. Treatment of females with testosterone and of males with estrone caused a reversal of the sex difference. Cholesterol concentration of hepatic bile was no higher after 2 months on the C-CA diet than after 2 days, but total cholesterol secreted per unit time (concentration x flow rate) was significantly elevated at 2 months.
Influence of tissue pressure on renal blood flow autoregulation
Authors: Gilmore J. P.
Published: December 2017

Experiments have been undertaken to determine the role which tissue pressure plays in renal blood flow autoregulation. The following results have been obtained: 1) During occlusion of the ureter of the dog undergoing mannitol diuresis renal blood flow changes little, or increases, while tissue and ureteral pressures may increase up to 70 and 100 mm Hg, respectively. 2) Rapid sustained increases in ureteral pressure are associated with a rapid initial decline in renal blood flow followed by a gradual return to or near the control value; during these blood flow changes the elevated needle and ureteral pressures are constant. 3) During ureteral occlusion vasodilator drugs have little effect on renal blood flow. 4) The decapsulated kidney autoregulates. These data indicate that renal blood flow autoregulation cannot be explained on the basis of the tissue pressure hypothesis, but rather give further support to the myogenic theory.
Electrolyte, water, and urea content in dog kidneys in different states of diuresis
Authors: Ruiz-Guiñazú Alfonso , Arrizurieta Elvira E. , Yelinek Laura
Published: December 2017

Thin kidney slices of dogs in hydropenia and water diuresis were analyzed for water, electrolytes, and urea content. The sodium and chloride contents are uniform throughout the cortex, but rise very markedly in the outer medulla, more during hydropenia than during water diuresis. Throughout the inner medulla a uniform content was observed, about 30% higher during hydropenia. The water content was uniform at all levels in the cortex, and increasing in the outer medulla, regardless of the state of hydration. In the inner medulla the content rose toward the papilla during water diuresis and decreased in the same direction during hydropenia. The urea content showed a very marked rise throughout the medulla during hydropenia and no significant rise during water diuresis. It was concluded that the great bulk of medullary sodium is pumped in the thick portion of the ascending limb of Henle and that the changes in water and urea contents bear the main responsibility in the creation of osmotic gradients within the inner medulla during hydropenia.
Carrier transport of glucose between blood and cerebrospinal fluid
Authors: Fishman Robert A.
Published: December 2017

The transfer of glucose, 2-deoxy-d-glucose, and fructose between blood and cerebrospinal fluid (CSF) of anesthetized dogs was studied, following either intravenous injection or intracisternal administration in artificial CSF. Glucose entry was not directly proportional to the concentration difference between blood and CSF. The CSF glucose concentration approached a maximum, despite increasing intravenous loads, suggesting saturation kinetics. Bidirectional molecular stereospecificity was demonstrated; the three hexoses enter and exit from CSF at increasing rates, fructose < glucose < 2-deoxyglucose. The slow entry of fructose is attributed to simple diffusion. The more rapid transfer of 2-deoxyglucose than of glucose suggests greater "affinity" of the former for the carrier. Bidirectional competitive inhibition between glucose and 2-deoxyglucose was demonstrated. Bidirectional countertransport ("uphill transport by counter flow") of glucose between the two compartments was shown. Glucose transfer into CSF was not affected by intravenous 30% urea. The data support the existence of a carrier transport system for glucose in membranes separating the two compartments.
Endogenous oxygen uptake of the hypothalamus in female rats
Authors: Moguilevsky J. A. , Malinow M. R.
Published: December 2017

The endogenous oxygen uptake has been determined in the hypothalamus, brain, hypophysis, and uterus of female rats. With the exception of the brain, similar changes have been detected in connection with estrous phases in all of these organs: lower respiratory rates were observed during diestrus and higher ones during estrus. Estradiol and progesterone were added in vitro to hypothalamus and brain slices of estrous and diestrous rats. Although both hormones consistently depressed the Qo2 in brain, such effects were seen only in the hypothalamus of estrous animals.
Buffer distribution in isolated perfused rat heart measured by rubidium 86
Authors: Shipp Joseph C. , Spencer James R. , Crevasse Lamar E.
Published: December 2017

The pattern of distribution of Rb86 in sections of the isolated perfused heart was determined as a measure of uniformity of coronary artery flow. Results suggest that coronary flow was uniform after nonrecirculated perfusion for 15 min. Similar results were obtained in hearts perfused for 30 and for 60 min. The distribution of Rb86 was comparable in hearts perfused for 30 min with perfusate circulated through either coarse porosity, sintered-glass filters or 5-µ Millipore filters. A nonuniform distribution of isotope was demonstrated with ligation of branches of coronary arteries and with the introduction of air. The results suggest that hearts perfused by recirculation of buffer through coarse porosity, sintered-glass filters have a uniform distribution of perfusate throughout the heart.
Smooth muscle contraction in presence of an inhibitor of K efflux
Authors: Bass Allan D. , Hurwitz Leon , Smith Bolton
Published: December 2017

Contractions of the isolated longitudinal smooth muscle from guinea pig ileum produced by pilocarpine are regularly accompanied by increases in the efflux of potassium ion. A concentration of 7.4 x 10–6 m pilocarpine produced a maximum smooth muscle contraction and an increase in potassium efflux which averaged 157% above that of unexcited fibers. In the presence of appropriate concentrations of the inhibitor (desoxycorticosterone acetate) pilocarpine evoked small to negligible increases in potassium efflux, whereas the smooth muscle contractions elicited were about 81% of the control. These data show that pilocarpine can produce a near maximal smooth muscle contraction in the absence of any pronounced change in outward flux of potassium ion.
Effect of vagal innervation on acid and pepsin response to histamine and gastrin
Authors: Passaro Edward P. , Grossman Morton I.
Published: December 2017

The acid and pepsin responses to a wide range of doses of gastrin extract and of histamine were determined in dogs that had both a fistula of the vagally innervated main stomach (GF) and a vagally denervated Heidenhain pouch (HP). The GFs gave the same maximal acid response with gastrin as with histamine whereas the maximal acid response of the HPs to gastrin was only 45% of that to histamine. Opening the GF increased the response of the HP to submaximal doses of gastrin and, to a lesser extent, of histamine. With the GF open, peak rates of secretion from the HP were not sustained, particularly with gastrin stimulation. Sustained increase in pepsin output over basal levels occurred in GFs with very low doses of gastrin but not with any dose of histamine and in HPs with all doses of histamine and of gastrin tested. In both GFs and HPs doses of histamine that were supramaximal for acid secretion suppressed pepsin secretion without a concomitant fall in acid secretion, a phenomenon not seen with stimulation with gastrin.
Influence of alloxan diabetes on growth hormone content of the rat hypophysis
Authors: Hazelwood Robert L. , Hazelwood Barbara S.
Published: December 2017

Homogenates of adenohypophysial tissue obtained from alloxan-injected adult male rats varying in duration and severity of diabetes, as well as from diabetic rats maintained on an insulin-replacement regimen, were assayed in immature hypophysectomized female rats. The ability of these crude hypophysial extracts to encourage tibial cartilage width expansion, gain in body weight, and to depress hematocrit and blood urea levels was determined. Significant decrements in ability to increase epiphysial cartilage width and ability to depress hematocrits were noted 14 to 28 days following injection of alloxan. Increasing the intensity of the diabetic state was associated with decreased growth-promoting potency of hypophysial preparations as well as with decreased ability to influence hematological indices. Hypophysial extracts taken from insulin-treated diabetic rats contained more growth hormone than equivalent amounts of tissue obtained from control rats. It is concluded that the adenohypophyses of diabetic rats contain diminished amounts of growth hormone and that insulin repairs or encourages greater than normal accumulation of somatotrophin in these animals.
Evidence for a thyroid-inhibiting factor of adenohypophysial origin
Authors: Posner Israel , Pimentel Enrique
Published: December 2017

Thyroids of normal or thyroxine ( T4)-pretreated rats were incubated in vitro in a serum medium containing I131. It was found that the addition of either a whole rat adenohypophysis, a crude rat anterior pituitary extract, or of commercial bovine thyrotrophin (TSH) to the medium caused a slight stimulation of I131 release and no apparent stimulation but rather an immediate and considerable inhibition of thyroid-I131 uptake. Preincubation of rat thyroid with crude anterior pituitary extract resulted in a prolonged inhibitory effect on the thyroid-I131 uptake. In vivo studies showed that shortly after TSH administration a similar inhibition of uptake occurred in normal rats, although allowing 24 hr for TSH stimulation brought about no change in iodine uptake in thyroids of normal and a marked increase in uptake by thyroids of T4-pretreated rats. The inhibition of thyroid-I131 uptake was assumed to have been caused either by TSH itself, or by a thyroid-inhibiting factor of adenohypophysial origin present in commercial TSH preparations as a contaminant.
Cardiovascular effects of catecholamines in experimental adrenal insufficiency
Authors: Lefer Allan M. , Sutfin Duane C.
Published: December 2017

The level of cardiovascular performance and the responsiveness of the cardiovascular system to exogenously administered catecholamines were determined in intact untreated dogs, in dogs treated with mepyrapone, and in bilaterally adrenalectomized dogs. Mepyrapone-treated dogs showed no significant alteration of base-line levels of performance. Adrenalectomized dogs exhibited reduced cardiac contractile force, arterial blood pressure, aortic blood flow, and a slower heart rate. Mepyrapone-treated dogs showed no impairment of contractile force responses except at high catecholamine doses (1.0–3.0 µg/kg, i.v.). Blood pressure and aortic flow responses were not impaired at any dose level. Adrenalectomized dogs exhibited a significant impairment of contractile force, and blood flow responses to low and moderate doses of epinephrine and norepinephrine (0.1–2.0 µg/kg, i.v.), but a dose of 3.0 µg/kg overcame the impairment. The blood pressure response was impaired over the three lower doses (0.1, 0.2, and 0.5 µg/kg), but not to higher doses of catecholamines.
Effects of chronic hypothalamic lesions on diurnal and stress corticosteroid levels
Authors: Slusher Margaret A.
Published: December 2017

The effect of chronic lesions on plasma corticosteroid levels has been assessed in an attempt to differentiate neuronal areas affecting diurnal corticosteroid rise from those involved in acute response to stress. In unanesthetized, unrestrained rats blood samples were collected through a chronic indwelling catheter on each of four experimental days at 9 and 10 am and 5 pm with or without addition of a stress applied at 9:45 am. Anterior hypothalamic lesions bilaterally destroying the periventricular zone and arcuate nuclei were associated with inhibition of the normal 5 pm rise but with normal rise in plasma corticosteroid levels in response to sound or to a 1-min electrical stimulation of the posterior diencephalon. Posterior tuber cinereum lesions were associated with normal 5 pm rise but with inhibition of response to sound. Response to ether stress was unaffected by any lesion. Thus the integrity of anterior hypothalamic areas appears essential for normal diurnal rise in plasma corticosteroid levels while more posterior areas are involved in mediation of pituitary-adrenal response to acute stress of sound.
Parachloromercuribenzoate on action potentials of Purkinje and ventricular fibers of hog heart
Authors: Kleinfeld Morris , Stein Edward , Murphy Bernard
Published: December 2017

Parachloromercuribenzoate (0.5 to 2.6 x 10–4 m) was administered to a hog Purkinje fiber ventricular muscle preparation and its effects on transmembrane action potentials of the two types of fibers were studied. Parachloromercuribenzoate produced changes in action potential of Purkinje but little change in that of ventricular fiber. The earliest alteration in Purkinje fiber was a decrease in overshoot. This was followed by a decrease in height of action potential and slowing in rate of depolarization. There was a decline in diastolic resting potential but this occurred late. The difference in response of the two types of fibers is not readily explainable. One possible difference is that the sulfhydryl groups in Purkinje fiber may be more available for binding with p-chloromercuribenzoate. Another hypothesis is predicated on differences in metabolism in two types of fibers. There is evidence to indicate that Purkinje fiber utilizes anaerobic glycolysis predominantly. A greater sensitivity of the glycolytic-dependent sulfhydryl enzymes to action of this agent would interfere with metabolism in Purkinje fiber and cause a decrease in its resting potential.
Measurement of myocardial blood flow using krypton 85
Authors: Cohen Lawrence S. , Elliott William C. , Gorlin Richard
Published: December 2017

Krypton 85 in solution was administered as a single rapid injection into the left ventricle in 11 human and 9 canine subjects. The myocardial clearance of the portion of injectate which entered the coronary system was sampled at the coronary sinus and coronary flow was derived from Kety's equation. A comparison with nitrous oxide or antipyrine-I131 coronary flows revealed a correlation coefficient of 0.86 ± 0.22 ( P = .005) with no statistically significant difference between paired samples.
Vasomotor function of smooth muscle in the main pulmonary artery
Authors: Somlyo Avril V. , Somlyo Andrew P.
Published: December 2017

Isotonic contractions were measured in helically cut strips of canine main pulmonary artery (MPA). Applied tension/unit area was of the order of magnitude of average tangential stress calculated for MPA wall in vivo. Angiotensin was found to be a highly effective vasoconstrictor in this preparation. Epinephrine, norepinephrine, phenylephrine, metaraminol, methoxamine, mephentermine and 5-hydroxytryptamine also produced significant vasoconstriction, while oxytocin and vasopressin were ineffective. Aeration with 100% CO2 resulted in slight vasodilation, followed by progressive vasoconstriction after pH fell below 6.0. Maximum shortening (Smax) was elicited by l-epinephrine in preparations under tensile stress of 6.4 x 104 to 16.5 x 104 dynes/cm2. Smax (average 20%) was directly related ( r = 0.78, P < 0.01) to the amount of elongation which took place during equilibration of strips under tension. The results suggest the feasibility of active regulation of MPA geometry by smooth muscle.