bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavior of pulmonary hypertension produced by serotonin and emboli
Authors: Hyland John W. , Piemme Thomas E. , Alexander Sidney , Haynes Florence W. , Smith George T. , Dexter Lewis
Published: December 2017

Pulmonary hypertension was produced in 25 dogs by infusion of serotonin, lycopodium spores, or polystyrene spheres. Flow through one lung was doubled by balloon occlusion of the opposite pulmonary artery, and the changes in calculated pulmonary vascular resistance of the unoccluded lung were observed. In the presence of pulmonary hypertension produced by serotonin, balloon occlusion produced a 51% fall of pulmonary vascular resistance in the unoccluded lung. A similar result was obtained with hypertension produced by small precapillary emboli 28 µ in diameter. Resistance fell 47% with occlusion of one artery. These results suggested that vasodilatation had occurred in the unoccluded lung. When pulmonary hypertension was produced by larger spheres, the fall of resistance seen in the unoccluded lung was only 18%. Significant vasodilatation had not occurred. The findings suggest active control of pulmonary vascular resistance by the precapillary arteriole.
Anaerobic functional activity of isolated rabbit atria
Authors: Yang William C.
Published: December 2017

Rabbit atria were subjected to prolonged periods of anoxia. Electrical and mechanical activities were measured under different conditions. It was found that rabbit atria, under anoxia, can maintain long periods of reduced activity in the presence of glucose. Sucrose, fructose, or galactose cannot replace glucose in maintaining the reduced activities of atria under anoxia. Glycolytic inhibitors, such as 2-deoxyglucose and iodoacetate, effectively inhibit this reduced atrial activity under anoxia. Energy formed during the glycolytic breakdown of glucose, therefore, can be used to maintain reduced activity of the rabbit atria.
Prevention in rats of narcosis produced by inert gases at high pressures
Authors: Bennett Peter B.
Published: December 2017

A technique is described for quantitative evaluation of inert gas narcosis in animals. The response of 46 adult Wistar rats to minimal electroshock was used in 102 experiments to determine the narcotic effect of nitrogen at 12.6 and 13.5 atm abs and argon at 12.6 atm abs, before and after the oral, intraperitoneal, and intravenous administration of alpha-(4-piperidyl)benzhydrol hydrochloride. The drug controlled the narcotic effect produced by these inert gases at pressure without, so far as could be observed, the occurrence of undesirable side effects. The effective dose was 40 mg (130–150 mg/kg body wt). Lower doses were only partially effective. The maximum protective action of the drug was some 48 hr after its administration.
Relative activities of several 3'- and 3':5'-alkyl and aryl thyromimetic agents
Authors: Greenberg Cyrus M. , Blank Benjamin , Pfeiffer Francis R. , Pauls John F.
Published: December 2017

The biological activity of several 3:5-diiodo-3'- and 3':5'-alkyl and arylthyronines as well as of some 3:5-diiodo-3'-isopropylthyroacetic acid analogues was determined following their subcutaneous administration to adult male rats. l(+) 3:5:3'-triiodothyronine (l-triiodothyronine) was used as the reference compound. l(+) 3:5-Diiodo-3'-isopropylthyronine was the only compound in this series found to be more active than l-triiodothyronine in all of the assays that were performed. It exhibited twice the calorigenic, 1.3 times the cholesterol-lowering, 1.8 times the antigoitrogenic, and 1.4 times the heart weight-increasing activity of the reference agent. This is the first thyromimetic substance reported to be more active in rats than the endogenous thyroid hormones. Each experiment consisted of injecting at least four doses of the agent to be assayed as well as of l-triiodothyronine to different groups of rats. The resulting data were evaluated statistically. Photographs of Courtald atomic models of several alkyl thyronines are presented for the purpose of indicating the possible importance of the relative "bulk" of the alkyl constituents compared to that of the iodine atom in the 3'-position.
Effect of glucose on incorporation of l-lysine-U-C14 into testicular proteins
Authors: Davis Joseph R. , Morris Robert N.
Published: December 2017

The incorporation of l-lysine-U-C14 into proteins of slices of a number of tissues of the rat has been studied in the presence and absence of glucose under aerobic conditions. The addition of 0.009 m glucose increased the incorporation of radioactive lysine into proteins of slices of rat testis and head of epididymis by 600 and 160%, respectively. Similar additions of glucose caused essentially no change to a 50% enhancement of protein labeling in slices of thymus, spleen, pancreas, tail of epididymis, kidney, brain, diaphragm, heart, liver, seminal vesicle, a number of transplantable rat tumors, and regenerating rat liver. The data obtained indicate that the enzymatic systems involved in the incorporation of labeled lysine into protein of the testis are more sensitive to the addition of exogenous glucose than those of a number of other tissues of the rat.
Modification of ovulatory mechanisms by postnatal administration of estrogen to the rat
Authors: Gorski Roger A.
Published: December 2017

The current studies have demonstrated that the single injection of 100 µg estradiol benzoate to 5-day-old female rats results in permanent sterility. When adult, these rats exhibit anovulatory vaginal cycles in which the stage of vaginal cornification predominates; they mate, but not in correlation with the vaginal cycle. Ovulation is not induced by mating or by progesterone injections, and only infrequently following electrical stimulation of the hypothalamus. By varying the amount of estrogen administered it was found that 5 µg is the minimal dosage capable of inducing this sterility syndrome. These and other data suggest that the female pattern of cyclic release of gonadotrophins differentiates in the absence of significant estrogen titers.
ATP content in the central nervous system of rats exposed to chronic hypercapnea
Authors: Navón Sofía , Agrest Alberto
Published: December 2017

Concentration of adenosine triphosphate in the medulla and in the forebrain of rats exposed continuously to gas mixtures containing 6–8% CO2 shows an exponential decay up to the 12th day. The slope has a k = 0.10, and it levels off between the 12th and 15th day of hypercapnea.
Platelets and blood coagulation in arterial and venous blood
Authors: Downie H. G. , Murphy E. A. , Rowsell H. C. , Mustard J. F.
Published: December 2017

Various tests of blood coagulation have been made on samples of blood collected simultaneously from the carotid arteries and contralateral veins in a series of pigs. Thirty-eight pigs were receiving Dicumarol in various doses and fifty-eight were receiving no treatment. Most of the tests showed no significant differences. The adhesive index, however, was higher in the arterial samples than in the venous in the pigs receiving Dicumarol. In the same group of animals, the platelet count was significantly higher in the arterial blood by about 8%. There is no ready explanation for this latter finding but the possible mechanisms are discussed at some length. Similar but not significant differences were found for these two measurements in blood samples from the untreated pigs. These findings raise some interesting questions and suggest that for purposes of comparison, samples should be obtained consistently from either the artery or the vein.
Effect of sympathetic stimulation on dog paw volume
Authors: Davis Darrell L.
Published: December 2017

Small vessel pressures and flows and changes in volume of the dog hind paw were recorded simultaneously to study the responses to various rates of sympathetic stimulation. Although a progressive change in small vessel responses occurred as the stimulation frequency was increased, the responses could be grouped into three categories. At the lowest stimulation frequencies (1–2/sec, and less) the constrictor response was predominantly arteriolar. During the stimulation period metatarsal vein pressures and paw volumes did not exceed prestimulation levels. At stimulation frequencies of 1–2/sec to 15–20/sec an initial arteriolar constriction was followed by appreciable arterial and venous constriction. Increases in venous resistance, coupled with continued arterial inflow, produced increased paw volume and pooling of blood in minute vessels. At stimulation frequencies of 20–25/sec marked arterial and venous constriction occurred. Arterial inflow was stopped and paw volumes were decreased even though venous resistance was increased.
Measurements of intrafollicular pressures in the rabbit ovary
Authors: Espey Lawrence L. , Lipner Harry
Published: December 2017

Pressures within rabbit Graafian follicles have been determined by direct cannulation with micro-pipettes. The average pressure in the antrum of 60 maturing follicles was slightly over 17 mm Hg. There was no difference in the pressures in precoital and postcoital follicles. The average pressure of 15 blood follicles (preatretic) was 50 mm Hg. A direct proportionality was observed between the blood pressure and follicle pressure, suggesting that colloid osmotic pressure contributes little to the total hydrostatic pressure in the follicle. Blebbing preceded the appearance of the ovulation cone. In six measurements made during ovulation, intrafollicular pressure dropped instantly from about 15 to 5 mm Hg at the time of rupture. Visible muscle-like contractions of the follicle, concomitant with recorded pressure changes, were seen in two of six ovulating follicles. A hypothesis explaining the mechanism of ovulation includes the concept that structural changes in the thecal wall result in ballooning and the appearance of an ovulation cone. Rupture of the ovulation cone occurs under the force of a steady pressure in the antrum.
Rat biliary tree during short periods of obstruction of common duct
Authors: Barber-Riley G.
Published: December 2017

The capacity of the biliary tree, and the residual volume of the original contents present at different time intervals following obstruction of the common duct, were measured at different pressures in experiments of short duration. The results showed: 1) the capacitance of the biliary tree increased with increasing back pressure; 2) the measured secretory rate was not reduced by back pressure; 3) leakage of bile from the biliary tree ("regurgitation") was absent (or constant) until the back pressure was about 75% of the maximum secretory pressure; 4) with the exception of a very small dead-space volume, the original contents of the biliary tree were removed exponentially during obstruction. It was concluded that biliary secretion continues unchecked during short periods of obstruction, that regurgitation occurs at sites which are uniformly distributed over most of the biliary tree, and that the "maximum secretory pressure" of the liver probably represents only the critical pressure at which secretion is equal to reabsorption.
Food intake of parabiotic rats
Authors: Han Paul Wei , Mu Jui-Yun , Lepkovsky Samuel
Published: December 2017

Food intake of parabiotic rats was studied for at least 24 days by using partitioned cages. After hypothalamic lesions were placed in one rat, the daily food intake of its normal partner remained at the same preoperative level. In control pairs, starvation of one rat did not cause the daily food intake to increase in the other rat. These findings, along with data from a pair with cross anastomosis of small intestines, clearly indicate that humoral signals for inhibiting and facilitating feeding, if they do exist, cannot be transferred readily through the parabiotic union. Other experiments showed that the parabiotic preparation can be used to study the regulation of water intake.
Influence of hematocrit ratio on survival of unacclimatized dogs at simulated high altitude
Authors: Smith Elvin E. , Crowell Jack W.
Published: December 2017

Eighty-six dogs were subjected to acutely induced, simulated high altitudes to determine the optimum hematocrit ratio for survival. High altitudes were simulated by diluting atmospheric air with nitrogen. Dogs with various hematocrit ratios were obtained by natural selection, hemorrhage, transfusion, and pretreatment with phenylhydrazine. Fifty-one dogs, in groups of 5–15, were placed in a closed chamber, and a 40,000-ft altitude was simulated by proper adjustment of the oxygen-to-nitrogen ratio. This altitude was maintained for a period of 6 hr. Most dogs with hematocrits less than 24 or greater than 66 died before the simulated altitude of 40,000 ft was attained; those with hematocrits of 24–30 survived from 1/2 to 5 hr. Some dogs with hematocrits of 30–65 survived the entire 7-hr period. However, no dogs with hematocrits from 37 to 54 died. The same procedures were repeated at a simulated altitude of 50,000 ft with a group of 38 dogs. The survival group was composed of dogs with hematocrits of 36–46. Dogs with hematocrits of 40–41 were conscious and active while those with hematocrits on either side of this value were comatose. These data indicate that the optimum hematocrit for survival of the unacclimatized dog at acutely induced high altitude is about 40. Deaths occurring on both sides of the optimum value may be explained by a simultaneous consideration of the curves depicting oxygen-carrying capacity of the blood, and blood viscosity, at all ranges of hematocrit.
Effects of manganese on Q-T interval and distribution of calcium in rat heart
Authors: Conrad Loyal L. , Baxter Donald J.
Published: December 2017

Electrocardiographic observations were correlated with the 2- and 24-hr uptake of Ca45 by the myocardium of the normal rat and the rat injected subcutaneously with manganese chloride. The distribution of Ca45 in the heart cell was determined by differential centrifugation and the effects of manganese noted. Normally, about 40% of the Ca45 in the rat heart was found in the microsomal fraction, the remainder being distributed equally in the other cell fractions at 2 hr. None was found in the supernatant material after centrifuging for 17 hr. After manganese injection the total uptake of Ca45 was doubled at 2 hr due to increases in the microsomal and 17-hr fractions. Control values were re-established by 24 hr. Electrocardiograms showed a significant prolongation of the Q-T interval at 2 and 24 hr after manganese injection. There was a significant decrease in serum calcium concentration 24 hr after the injection of manganese.
Aortic pressure during ventricular ejection as a determinant of cardiac performance
Authors: Levy Matthew N. , Imperial Elias S. , De Mattos A. Darwin , Zieske Harrison
Published: December 2017

In the isolated, supported, canine heart preparation, the left ventricle was subjected to brief, repetitive, identical increases in outflow resistance. By varying the timing of the application of the augmented resistance, it was possible to subject the ventricle to a series of different aortic pressures during the ejection phase of systole, in the face of a virtually constant change of arterial impedance. The aortic diastolic pressure, the minimum pressure during the preceding beat, was used as an index of the aortic pressure range against which the ventricle contracted during each experimental beat with increased resistance. For any given increment of resistance, peak systolic pressure was an approximately linear, direct function of aortic diastolic pressure, and peak flow velocity and stroke volume were approximately linear, inverse functions of the diastolic pressure over the range of variations which was studied. Peak power generation and stroke work were also affected both by the magnitude of the resistance and by the level of the diastolic pressure. However, the direction in which these changes occurred was variable. Presumably this was dependent upon the position on the load-power and load-work curves at which the heart was operating during the control beats, as well as upon the magnitude of the changes in resistance and diastolic pressure which were imposed.
Use of nitrous oxide to measure mammary blood flow in anesthetized lactating goats
Authors: Reynolds Monica
Published: December 2017

The N2O diffusion method has been adapted to measure blood flow in anesthetized lactating goats. The partition coefficient for N2O between blood and mammary tissue was found to be 1.008 (se 0.008). N2O concentrations, determined during gas inhalations in all four mammary veins simultaneously, were found to be the same provided the catheter was placed deeply in the subcutaneous abdominal vein. Thirty minutes was required for venous N2O concentration to reach 0.15 vol % of arterial concentration, which was 97% of true equilibrium. Flow values obtained by the N2O method differed from those obtained by the Shipley-Wilson rotameter method by 6%. The N2O method yields results accurate to within 7% of the measured value and is satisfactory for measuring an average mammary blood flow for a 30-min period. Blood flow obtained from ten experiments averaged 32.8 ± 5.1 ml/min per 100 g tissue.
Granulokinetics in normal dogs
Authors: Raab S. O. , Athens J. W. , Haab O. P. , Boggs D. R. , Ashenbrucker H. , Cartwright G. E. , Wintrobe M. M.
Published: December 2017

Dog granulocytes were labeled in vitro with radioactive diisopropylfluorophosphate (DFP32) and then returned to the circulation of the donor. Granulocytes were separated from whole blood by utilizing hexadimethrine bromide as the sedimenting agent and saponin as a lysing agent. The labeled granulocytes disappeared from the circulation in an exponential fashion with a mean (±1 sd) half-time disappearance of 5.6 ± 0.95 hr. The size of the total blood granulocyte ( TBGP), circulating granulocyte ( CGP), and marginal granulocyte ( MGP) pools, and the granulocyte turnover rate ( GTR) were measured in 31 normal, unanesthetized dogs. The mean values ± 1 sd, expressed as number of cells x107/kg body wt., were as follows: TBGP, 102 ± 34.8; CGP, 54 ± 20.7; MGP, 48 ± 23.4; and GTR, 305 ± 111.5 cells/kg day. The values observed in anesthetized and in unanesthetized, splenectomized dogs were not significantly different from the above values.
Electrolyte and juxtaglomerular changes in adrenal regeneration hypertension
Authors: Rapp John P.
Published: December 2017

One week after adrenal enucleation in rats skeletal muscle and serum electrolytes followed a pattern similar to adrenal insufficiency. However, at the 2nd week of adrenal regeneration there was a marked shift of sodium into and potassium out of skeletal muscle cells which persisted through the 8th week. These cation shifts correlated with increases in blood pressure and renal and heart weights. Increased sodium and decreased potassium in skeletal muscle cells and increased blood pressure and increased renal and heart weights were potentiated by saline feeding and failed to occur with adrenal regeneration in the hepatic portal circulation. Juxtaglomerular granular cells were examined in rats killed at 1, 2, 4, 6, and 8 weeks after adrenal enucleation. No evidence was found to indicate a change which would be expected to initiate a blood pressure rise and the degranulation observed was interpreted as the result rather than the cause of the blood pressure change.
Bilateral cervical vagotomy: a long-term study on the unanesthetized dog
Authors: Shepard Robert S. , Whitty Albert J.
Published: December 2017

Bilateral cervical vagotomy was followed by prolonged changes in heart rate, blood pressure, and respiration, and a progressive deterioration of cardiac function. This study was based on recordings from 18 unanesthetized, unrestrained, reclining dogs prior to and after gastroenterostomy, arterial catheterization, and bilateral cervical vagotomy. During the first 7 days after denervation, the heart rate was almost doubled and the pulse pressure was decreased. The diastolic pressure was increased only on the first day, whereas on the second day after denervation the systolic pressure became significantly lower. The markedly elevated heart rate was maintained for 3 weeks. There was a complete loss of inspiratory tachycardia for 20 weeks, a prolonged inspiratory period for 2 weeks, and a high incidence of retching and vomiting for over 43 weeks. Although the animals refused to exercise strenuously, they were fully ambulatory and showed normal interest in their surroundings. Death in 13 cases occurred by the second week postvagotomy and was associated with lung congestion or consolidation, and in two cases the liver had a nutmeg appearance.
Glucose uptake by diaphragms from rats subjected to hemorrhagic shock
Authors: Drucker William R. , DeKiewiet John C.
Published: December 2017

The marked metabolic alterations that occur in hemorrhagic shock have been ascribed to tissue anoxia occasioned by hypovolemia. Other investigators, utilizing different shock models, have explained the initial metabolic changes as secondary to humoral changes. In skeletal muscle, anoxia is known to cause an increased glucose uptake, whereas epinephrine causes a decreased uptake. The present work was undertaken to explore some alterations in carbohydrate metabolism during hemorrhagic shock in rats, when both tissue anoxia and an altered humoral state are present. Hemidiaphragms from rats subjected to a standardized hemorrhagic shock procedure and from control rats were excised and incubated aerobically in bicarbonate buffer containing glucose. After 1 hr of incubation aliquots of the media were analyzed for glucose and lactate. The results demonstrated a significantly greater glucose uptake and lactate production by the diaphragms from the bled rats. The data suggest that, during hemorrhagic shock in rats, tissue anoxia leads to a predominance of anaerobic metabolism and a severe depletion of intracellular energy, resulting in an increased uptake of glucose in skeletal muscle despite the concomitant altered humoral state which ordinarily would inhibit glucose uptake.
Effect of acute hemorrhage on the calculated lung hematocrit
Authors: Eich Robert H. , Smulyan Harold , Vincent William A. , Furth Frank W.
Published: December 2017

The hematocrit for the lesser circulation was determined in 22 dogs using Cr51-tagged cells and either indocyanine green or radioactive serum albumin as the plasma tag. To assess the variation due to methodology, a reproducibility study alone was done in 8 dogs, and in 14 dogs measurements were made before and after the blood pressure was lowered to 50 mm Hg by acute hemorrhage. The lung hematocrit was obtained both from the cell and plasma volume measured by the indicator dilution technique and by the ratio of the mean circulation times. There was no significant difference between the calculated lung hematocrit and the peripheral hematocrit in the control state or following hemorrhage.
Activation of a fibrinolytic system in a dog with mast cell tumor
Authors: Ende Norman , Auditore Joseph V.
Published: December 2017

Injection of minute amounts 48/80 (35 µg/kg) into a dog possessing widespread mast cell tumors produced an interesting constellation of biochemical and pharmacological responses on the cardiovascular and hematologic systems. Severe cardiac irregularities and an intense lowering of blood pressure occurred. The most obvious changes which occurred on the blood coagulation system were a lowering of the prothrombin consumption and a prolonged increase in the coagulation time. Of paramount importance, however, was the intense fibrinolytic activity which developed in this animal. This phenomenon was also observed in animals not bearing mast cell tumors but occurred only when very high levels of 48/80 (0.75 mg/kg) were administered. Euglobulin fibrinolytic studies suggest that the observed intense fibrinolytic activity may be partially independent of euglobulin system. Heparin, histamine, and protamine in low concentrations did not activate the fibrinolytic system but produced inhibition in high concentrations (10 µg/ml). Canine mast cell tumors contain considerable esterase and proteolytic activity but there was no obvious evidence of their release into the blood after injection of 48/80 along with histamine, but local proteolytic activation in the mast cell tumor occurred.
Effects of norepinephrine and angiotensin on total and venous resistance in the kidney
Authors: Zimmerman B. G. , Abboud F. M. , Eckstein J. W.
Published: December 2017

The intact kidney of anesthetized dogs was perfused at constant blood flow. Small vein pressure (SVP) was measured from a catheter which was passed through the main renal vein deep into the kidney. Perfusion pressure (PP), tissue pressure (TP), and inferior vena caval pressure also were recorded. Norepinephrine and angiotensin administered intra-arterially produced large increases in PP and small increments in SVP. The rise in SVP was usually accompanied by an increase in TP. Evidence indicated that augmentation in venous resistance was caused by a direct stimulatory action of the agents on venous smooth muscle. Tissue pressure appears to be increased secondarily to SVP because of an increased intravascular volume and decreased tubular reabsorption. Sympathetic nerve stimulation produced small changes in SVP for large increments in PP as did the exogenous administration of norepinephrine. These results indicate that the arterial side of the kidney possesses a much greater constrictor capacity compared to the venous side and that renal vasomotor adjustments are made mainly on the arterial side of the bed.
Effects of steroids on the course of hereditary muscular dystrophy in mice
Authors: Dowben Robert M. , Zuckerman Leon , Gordon Paul , Sniderman Stephen P.
Published: December 2017

The administration of anabolic-androgenic steroids or digitalis glycosides to mice with hereditary muscular dystrophy prolonged their life span, whereas treatment with estrogens, deoxycorticosterone or aldosterone resulted in a significantly lower mean attained age. Of the anabolic steroids, 1-methyl-Δ1-androstenolone acetate, Δ1-17α-methyltestosterone, and methyltestosterone were the most effective compounds tested. Prolongation of the life span was accompanied by a slowing in the rate of deterioration of muscle strength. Dystrophic animals pretreated with digitoxin or 1-methyl-Δ1-androstenolone acetate showed a significant lowering of the abnormally high muscle sodium and chloride in control dystrophics. Pretreatment of dystrophic mice with 1-methylΔ1-androstenolone alone or together with digitoxin resulted in a significant lowering, from the abnormally high values characteristic of dystrophic muscle, of the potassium efflux from excised peroneus longus muscles.
Effect of urea osmotic diuresis on potassium excretion
Authors: Gonick Harvey C. , Coburn Jack W. , Rubini Milton E. , Maxwell Morton H. , Kleeman Charles R.
Published: December 2017

An increased solute load per remaining functioning nephron may enhance K excretion and aid in maintaining K balance in chronic renal failure. An analogous model was sought by inducing progressive osmotic diuresis with urea in a) water-loaded dogs with minimal K excretion, b) dogs receiving K infusions at intermediate rates of 207–280 µEq/min, and c) dogs receiving K infusions at maximal tolerated rates of 400–600 µEq/min. Urea diuresis significantly augmented K excretion in experiments in which basal K excreted-to-K filtered ratios (KE:KF) were minimal (.02–.03) or intermediate (.20–.73), but when control ratios approached 1.0, urea loading became progressively less effective. The slight increment in K excretion with low basal KE:KF ratios (19 µEq/min) suggested partial inhibition of proximal reabsorption; the more marked increment in K excretion at intermediate KE:KF levels (130 µEq/min) is consistent with enhancement of K secretion following increased delivery of Na to the distal exchange sites. Once distal K secretion was maximally stimulated by K loading, however, it was not further affected by solute diuresis or augmented Na excretion.
Depression of phagocytic activity and immune response by methyl palmitate
Authors: Di Luzio N. R. , Wooles W. R.
Published: December 2017

Intravenous administration of methyl palmitate produced a marked depression of the phagocytic activity of the RES. Histological evidence indicates that the RE-depressant effect exerted by methyl palmitate is not due to destruction of RE cellular elements but rather to an interference with the phagocytic activity of Kupffer cells. The functional activity of parenchymal cells was unaltered in RE hypofunctional mice. A depressed functional state of the RES, existing at the time of antigenic challenge with sheep erythrocytes, was associated with a profound inhibition of antibody formation during the primary and secondary immune response. This reduced antibody formation was not associated with alterations in the total circulating leukocyte level nor in the percentage of lymphocytes in peripheral blood. The employment of methyl palmitate to produce phagocytic and immunological paralysis is proposed.
Effect of hemorrhagic shock on release of norepinephrine by tyramine
Authors: Harrison Donald C. , Chidsey Charles A. , Braunwald Eugene
Published: December 2017

This study was undertaken to determine if the sympathetic discharge which accompanies hemorrhagic shock modifies the response to tyramine. In eight dogs the dose of tyramine equipressor to 1.0 µg/kg min of norepinephrine was 85 ± 8 µg/kg min in the control state, but had risen to 301 ± 55 µg/kg min after 4 hr of hypotension. In four dogs in which the norepinephrine pool had been labeled with tritiated norepinephrine, injection of tyramine into femoral arterial blood released large quantities of norepinephrine into the femoral venous blood during the control period. After 4 hr of hypotension, the output of radioactive norepinephrine by tyramine was greatly reduced. These findings support the view that the diminished responsiveness to tyramine after prolonged hypotension is due to decreased release of norepinephrine. Since there was no detectable decrease in the norepinephrine concentration of atrial appendage in eight dogs after 4 hr of shock, the diminished release of norepinephrine by tyramine in shock may have been due to the depletion of the small portion of the norepinephrine store releasable by tyramine.
Mechanical events of in vivo rabbit and cat spleen
Authors: Farrell Marcus J. , Camougis George
Published: December 2017

Splenic contractions were recorded in 23 rabbits and 6 cats under urethan and pentobarbital anesthesia. Rabbit splenic contractions consist of two distinct phases, a higher-frequency contractile phase (CPI) occurring every 10–45 sec and a slower-frequency contractile phase (CPII) occurring every 5–20 min. Bilateral adrenalectomy eliminates CPII, and splenic nerve block eliminates CPI. Cat splenic contractions consist of only the higher-frequency CPI phase. Bilateral adrenalectomy or splenic nerve block in the cat causes only a reduction in the contractile frequency. Simultaneous bilateral adrenalectomy and splenic nerve block eliminates splenic contractions in both rabbits and cats.
Hemodynamic responses to induced tachycardia in methylene blue-treated dogs
Authors: Afonso Skoda , Rowe George G. , Castillo Cesar A. , Crumpton Charles W.
Published: December 2017

The present study relates to metabolic, and systemic and coronary hemodynamic effects of methylene blue in five anesthetized dogs (group I) and of electrically induced tachycardia in ten dogs pretreated with methylene blue (group II). In group I body oxygen consumption increased slightly. In group II coronary blood flow, cardiac metabolic rate for oxygen, and right ventricular work increased significantly while coronary vascular resistance decreased significantly. The observed pattern of changes is not different from that produced by induced tachycardia in untreated dogs. Methylene blue does not alter the usual response of coronary circulation to cardiac acceleration.
Transient arterial lactic acid changes in unanesthetized dogs at 21,000 feet
Authors: Cain S. M. , Dunn J. E.
Published: December 2017

Blood lactic acid levels have been reported by some to be elevated during exposure to altitude and by others to be unaffected. Both the hyperventilation caused by hypoxia and tissue hypoxia itself should cause a rise in blood lactic acid, the latter factor being reflected primarily as excess lactate. After a 3-hr control period at ground level, unanesthetized dogs were exposed for 8 hr to 21,000 ft simulated altitude (Pb = 335 mm Hg). Arterial blood samples were drawn frequently from a Teflon T-cannula surgically placed in a carotid artery 1 or 2 days prior to the experiment. Lactic and pyruvic acid concentrations, Pco2, Po2, and pH were measured. At altitude, the average arterial Po2 was 32 mm Hg, Pco2 was 24 mm Hg, and pH was 7.50. All control values fell in normal ranges. Although the magnitude of changes differed among animals, arterial lactic acid reached a peak value within the first 2 hr at altitude and gradually declined thereafter and, in most animals, closely approached the control value during the 8th hr at altitude. Excess lactate changed in a similar manner. The decline in lactic acid, with no concomitant relief of arterial hypoxia and hypocapnia, remains unexplained.
Insulin and epinephrine effects on platelet histamine release in a plasma-free system
Authors: Tidball M. E.
Published: December 2017

When rabbit platelets were isolated from plasma and resuspended in a simple saline medium, minimal histamine release occurred. Resuspension of platelets in Krebs-Henseleit bicarbonate buffer was associated with spontaneous and complete histamine release. The presence of glucose in the Krebs buffer reduced release to about half, thereby enabling the study of both stimulation and inhibition of platelet histamine release in the same test system. In the presence of glucose, insulin decreased histamine release whereas epinephrine increased the extent of platelet histamine release. The findings indicate that rabbit platelets can be removed from the complexities of their usual blood environment to be utilized directly as a source of histamine for the study of histamine release. They demonstrate that a balanced saline medium provides conditions capable of promoting complete histamine release. Further, the results suggest that glucose metabolism is implicated in the release of histamine from rabbit platelets, and that histamine release is a phenomenon related to other homeostatic mechanisms which regulate cell processes under physiologic conditions.
Return of neural responses after autotransplantation of the heart
Authors: Willman Vallee L. , Cooper Theodore , Hanlon C. Rollins
Published: December 2017

Complete excision and reimplantation of the canine heart has been accomplished with survival in 25 dogs. One animal has now been followed for 30 months and six others have survived 12–24 months. Tests of innervation status have been applied during various intervals in a number of dogs from 7 days to 24 months after cardiac autotransplantation. The total extrinsic denervation which necessarily accompanies this surgical procedure appears to persist as long as 11 months. After 1 year vagal stimulation decreases the heart rate and stimulation of the stellate ganglia causes cardiac acceleration or augmentation. Injections of tyramine, norepinephrine, and veratrum viride alkaloids are followed by responses identical to those obtained in normal dogs. The catecholamine content of the myocardium returns to normal levels. We interpret the appearance of these responses as a demonstration that connection has been reestablished with the extracardiac nervous system.
Neurohumors in hypothalamic substrates of reward
Authors: Olds J. , Yuwiler A. , Olds M. E. , Yun C.
Published: December 2017

Chemicals in very small amounts were directly applied in the lateral hypothalamic area, where electric stimulation causes maximal positive reinforcement behavior. Effects on operant behavior rates of the chronic animals were measured. The independent variable was the chemical microinjection which followed each response; the dependent variable was the response rate. Response rates produced by carbamylcholine were significantly higher than those produced by NaCl; those produced by substances which chelate calcium were higher still and were counteracted when epinephrine, norepinephrine, or serotonin was added to the injected solution. Although individual animals sometimes failed to respond to an excitatory solution, a group of four rarely failed to place a chemical or solution correctly as yielding low, moderate, or high response rates. Final characterization of a chemical was determined by use of larger numbers and by statistical analyses which showed that findings related to carbamylcholine and to epinephrine, norepinephrine, and serotonin were repeatedly significant at 0.01 levels or better.
Physiologic effects of chronic exposure to phosgene in dogs
Authors: Rossing Robert G.
Published: December 2017

Recurrent exposure of dogs to phosgene gas produces a chronic obliterative bronchiolitis with a characteristic physiologic picture. After an acute phase, in which changes in elastic behavior predominate, a definite increase in lower airway resistance is seen which persists throughout the period of exposure. Accompanying this change the uniformity of distribution of inspired air is progressively disturbed as evidenced by nitrogen washout curves. In addition, microscopic changes suggestive of early, peribronchiolar emphysema are seen.
Carbohydrate metabolism of mice exposed to simulated changes in gravity
Authors: Oyama Jiro , Platt William T.
Published: December 2017

Unrestrained mice were centrifuged for varying periods ranging from 0.5 to 10 hr at 2.5, 5, and 10 x gravity. Liver glycogen and blood glucose levels increased significantly depending on the g load and exposure time. Adrenalectomy completely abolished the glycogen deposition response. The glycogen response was a critical function of the age of mice; unweaned mice did not respond. Blood corticosterone increased significantly prior to the deposition of glycogen. Centrifuged fed mice deposited three times the amount of glycogen of fasted mice. There was no significant difference in the amount of glycogen deposited in centrifuged mice previously starved for 1, 2, or 3 days. It is concluded that the increased glycogen deposited following centrifugation is effected by an increased elaboration of adrenal corticosterone.
Effect of alloxan on permeability of pancreatic islet tissue in vitro
Authors: Watkins Dudley , Cooperstein S. J. , Lazarow Arnold
Published: December 2017

The effect of alloxan on the permeability of toadfish islet slices was studied in vitro at 0 C, pH 7.0. When islet slices were incubated in d-mannitol-1-C14, a compound which does not enter cells, the C14 content of the slice reached 30% of that of the medium. In the presence of 2.5 x 10–4 m unlabeled alloxan (a concentration which may be present following injection of a diabetogenic dose), the C14 content of the tissue increased to about 50%. Alloxan also increased the loss of protein and insulin from the islet. This effect was specific for islet; higher concentrations of alloxan had no effect on any other tissue tested. Alloxanic acid, the nondiabetogenic decomposition product of alloxan, had no effect. p-Hydroxymercuribenzoate did not affect permeability but it potentiated the action of alloxan. Pretreatment of islet slices with glutathione or cysteine protected them against the subsequent action of alloxan; however, treatment with these agents after treatment with alloxan did not reverse the alloxan effect. These results suggest that alloxan may exert its diabetogenic effect by damaging the ß-cell membrane, thereby increasing its permeability.
Plasma and renal clearance of exogenous erythropoietin in the dog
Authors: Weintraub Arthur H. , Gordon Albert S. , Becker E. Lovell , Camiscoli James F. , Contrera Joseph F.
Published: December 2017

The pattern of plasma and renal clearance of purified sheep erythropoietin (ESF) was studied in unanesthetized dogs given a single intravenous injection of the hormone. Creatinine and PAH clearance measurements were also made up to 5 hr after ESF administration. Plasma clearance of ESF was found to be essentially biphasic: half-times for an initial rapid phase (0–1 hr) ranged from 20–45 min while those for the slower phase (1–24 hr) were of the order of 9–10.5 hr. Despite the loss from the plasma compartment of up to 70% of the injected dose of ESF within 3.5 hr, urinary recovery of the factor was quite low: about 2% of the injected dose in two experiments where 1,600 units were given and about 5% in a third experiment in which a dose of 3,200 units was employed. Excretion rates of the factor were found to be uniformly low and ESF clearance ranged from 0.1 to 0.6 ml/min. Some correlation between plasma levels and excretion rate of ESF was obtained. ESF clearance represented only a small fraction (0.1–1.4%) of the glomerular filtration rate. Injection of the hormone did not markedly influence creatinine or PAH clearance.
Effect of intestinal bypass on cholesterol absorption and blood levels in the rabbit
Authors: Buchwald Henry , Gebhard Roger L.
Published: December 2017

A chronic in vivo preparation for the study of cholesterol absorption is described. Ten rabbits which had undergone ileocecal valvuloplasty, ten rabbits subsequent to upper small intestinal bypass and ileocecal valvuloplasty, and ten rabbits with lower small intestinal bypass (including the ileocecal valve), are compared to ten normal controls, on the basis of blood radioactivity, and whole blood cholesterol levels, following a force-fed standard test dose of cholesterol-4-C14, 10 mg, 0.4 µc/mg. The conclusions arrived at from the data are that the entire small intestine is capable of absorbing cholesterol, that bypass of either the upper or the lower half of the small intestine results in a marked (> 80%) reduction in the blood radioactivity subsequent to the oral test dose, and that there is a functional difference between the upper and the lower small intestinal bypass groups. Transit time in the small intestine appears to play a major role in the amount of cholesterol absorbed. To achieve both a marked lowering of cholesterol absorption and circulating cholesterol levels, the most efficacious surgical site of bypass of the small intestine is the ileum.
Protection by restraint against parathyroid-extract intoxication in absence of the adrenals
Authors: Selye H. , Gabbiani G. , Tuchweber B.
Published: December 2017

Forced immobilization protected the rat against the soft-tissue calcinosis normally produced by large doses of parathyroid extract. This protection was evident even in adrenalectomized animals maintained on corticoids; indeed, in these, exposure to the severe stress of prolonged restraint actually counteracted the otherwise fatal effect of intense hyperparathyroidism.
Comparison of effect of environmental and preoptic cooling on plasma cortisol levels
Authors: Chowers I. , Hammel H. T. , Stromme S. B. , McCann S. M.
Published: December 2017

The acute exposure of dogs to an environmental temperature of 0 C evoked an elevation in plasma cortisol concentration which was apparent within 15 min and persisted for the 45 min of exposure. Gradual cooling of the environment over a 45-min period to a minimal temperature of 0 C failed to elevate plasma cortisol concentrations, although other compensatory mechanisms such as cutaneous vasoconstriction were active. Acute lowering of preoptic temperature also evoked a rise in plasma cortisol concentrations associated with lowering of pinna and elevation of rectal temperature. In this case the response was transient; plasma cortisol levels began to fall after 15 min of cooling even though cutaneous vasoconstriction was maintained. The results are interpreted to mean that acute lowering of environmental or preoptic temperature can activate the pituitary-adrenal system.
Follicular pressure and distensibility in ovulation
Authors: Rondell Paul
Published: December 2017

Micropipettes were introduced into follicles of exteriorized ovaries of rabbits anesthetized with pentobarbital. One pipette served for measurement of hydrostatic pressures, a second for the injection of small, measured amounts of saline. Impending ovulation did not measurably influence intrafollicular hydrostatic pressure. Artificial rupture could not be induced by increasing intrafollicular pressure by the injection of fluid. Tension-length diagrams for the elastic elements of the follicular wall, constructed from pressure measurements made following intrafollicular injections, indicate that a large increase in extensibility precedes rupture. Such a change in the physical characteristics of the follicle wall appears to be an essential part of the mechanism of ovulation.
Persistence of lung edema and arterial pressure rise in dogs after lung emboli
Authors: Weisberg H. , Lopez J. F. , Luria M. H. , Katz L. N.
Published: December 2017

Bilateral pulmonary edema was present in dogs autopsied 24 hr after pulmonary embolization. Mean pulmonary artery pressure remained elevated during this period. Most others, which survived up to the 3rd day and died spontaneously after embolization, showed edema at autopsy. Longer survivors showed no edema. Edema severity during the first 2 days was roughly related to the pressure rise during the 1st hr after embolization. Immediate significant pulmonary artery pressure rise, predominant in dogs succumbing by the 3rd day, was not as common in those surviving longer. Thus, survival time showed an inverse relationship to immediate pulmonary artery pressure elevation. In another 17 dogs followed as long as 10–23 months after embolization, 53% showed a significant rise in pressure at the end and some animals also had histologic pulmonary vascular changes. In some instances acute elevation of pulmonary artery pressure at embolization may anticipate chronic pulmonary arterial hypertension. The problem is the creation of embolism which elevates pulmonary arterial pressure without animals succumbing acutely to the associated pulmonary edema.
Myocardial catecholamines and ventricular performance during carotid artery occlusion
Authors: Gilmore J. P. , Siegel J. H.
Published: December 2017

Under conditions of constant cardiac output, heart rate, aortic pressure, and relatively constant coronary blood flow, carotid artery occlusion is associated with a significant decline in left ventricular end-diastolic pressure, i.e., an increase of myocardial contractility. This decline in left ventricular end-diastolic pressure is significantly reversed by bilateral ansectomy. During carotid artery occlusion coronary venous catecholamines showed varying responses relative to the changes in arterial catecholamine levels. The results indicate that during carotid occlusion both increased myocardial utilization and release of catecholamines may occur.
Cardiac function curves in conscious dogs
Authors: Bishop V. S. , Stone H. L. , Guyton A. C.
Published: December 2017

Repeated ventricular function curves were determined over a period of several weeks in seven conscious dogs. The atrial pressures were raised by infusing Tyrode's solution through a large catheter chronically implanted in the left jugular vein while recording systemic arterial pressure, right and left atrial pressures, heart rate, and ventricular output. Ventricular output was measured continually by chronically implanted electromagnetic flow probes. Right and left ventricular output curves, left ventricular minute work curves, stroke volume curves, and stroke work curves were run periodically on all animals in this study. The plateaus of the ventricular output curves were reproducible in each animal from day to day. The average deviation from each animal's mean plateau was found to be only 2.04% (± 0.39% sem). The deviations ranged from .5% to 3.5% of the mean plateau valves. However the left ventricular minute work curves and the stroke work curves were not consistant. These curves always had a descending limb associated with them.