bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Heart Rate on Oxygen Consumption of Isolated Dog Heart Performing No External Work
Authors: Van Citters Robert L. , Ruth William E. , Reissmann Kurt R.
Published: December 2017

The oxygen consumption of the beating dog heart, performing no external work, was measured in modified Langendorf preparations. Increasing heart rates, induced by rewarming of the cooled sinus node, were associated with linear increments in oxygen consumption. By extrapolation of these measurements, an average cardiac maintenance metabolism at zero rate of 1.98 cc O2/min. and 100 gm heart weight was found. Above this resting metabolism the energy cost of contraction at zero external work amounted to from .83 to 1.18 cc O2/100 beats and 100 gm heart. Measurements of the cardiac oxygen consumption during constant external work per unit of time and while the same heart was performing no external work directly demonstrated the decreased energy cost of external work at slower heart rates.
Adrenal Glands in the Development of Renal Hypertension in Rats
Authors: Fregly Melvin J.
Published: December 2017

The adrenal glands of the rat do not appear to be necessary for the development of experimental renal hypertension by kidney encapsulation. Male and female rats became hypertensive when both kidneys were encapsulated with latex envelopes whether they were adrenalectomized two weeks prior to or at the time of kidney encapsulation. The type of hypertension produced in adrenalectomized rats did not differ from that of rats with intact adrenals with regard to time course of development of the elevated blood pressure (6–8 weeks), maximal elevation attained (190–220 mm Hg), polydipsia and hypertrophied hearts.
Exogenous and Endogenous Histamine-Induced Potassium Release as Modified by the Antihistaminics
Authors: Macmillan William H.
Published: December 2017

Exogenous histamine or endogenous release of histamine, mediated through the action of compound 48/80 in doses of 50 µg/kg in the cat, results in a similar elevation of the concentration of potassium in the extracellular fluid. That these actions are due to the release of histamine and not to 48/80 per se has been determined by an analysis of the time-potassium release curves in both cases and the effectiveness of the antihistaminics in altering the depressor responses and potassium changes in each case. Diphenhydramine, pyrilamine and phenergan were used as representative antihistaminics. Phenergan, the most specific agent of this group, was shown to be most effective in depressing the exogenous and endogenous histamine induced hyperpotassemia. It is concluded that the alterations produced by exogenous histamine on potassium distribution in the cat are similar to those changes produced by endogenous histamine.
Action of Digitalis on the Nonfailing Heart of the Dog
Authors: Cotten Marion deV. , Stopp Phyllis E.
Published: December 2017

Ouabain induces a moderate increase in the contractility of the nonfailing heart of the dog with a complete circulatory system in doses which do not produce electrocardiographic signs of digitalis intoxication. The increased contractility was demonstrated both by the increase in ventricular contractile force and by the higher ventricular function curves obtained after administration of ouabain. The drug also increased systemic peripheral resistance and blood pressure, decreased systemic output, heart rate, left and right atrial pressures, and produced only small, variable changes in left ventricular stroke work. The reduction in systemic output and left atrial pressure and the absence of substantial changes in stroke work after ouabain appeared to be the result of a decrease in venous return to the heart. Evidence for this interpretation was obtained from experiments in which left atrial pressure was kept constant during the actions of ouabain by infusing 100–300 cc of whole blood. Under these conditions, ouabain brought about moderate increases in systemic output and left ventricular stroke work as well as in contractile force even though the changes in heart rate and blood pressure were comparable to those obtained in experiments in which left atrial pressure was uncontrolled. The data presented indicate that ouabain has two primary hemodynamic effects in the normal animal, namely, a direct cardiac stimulant action and a peripheral action resulting in a decreased venous return. The relationship of these findings to the mechanism of action of digitalis in congestive heart failure is discussed.
Relation of the Difference in Pressure Across the Mitral Valve to the Amplitude of the First Heart Sound in Dogs With Atrioventricular Block
Authors: Siecke Helmut , Essex Hiram E.
Published: December 2017

Measurements of the left atrial and ventricular pressure pulse in dogs with complete atrioventricular (AV) heart block revealed positive and negative differences in pressure across the mitral valve which were associated with high and low amplitudes of the first heart sound, respectively. Congestive heart failure, infusions and bleeding altered the duration of the negative difference in pressure and the amplitude of the first heart sound during atrial diastole. High and low amplitudes of the first heart sound are coincident with the opened and closed AV valves, respectively. The position of the valve leaflets at the onset of ventricular excitation seems to affect the rise of the ventricular pressure.
Effect of X-Irradiation on the Function of Adrenal Autotransplants in the Rat
Authors: Wyman Leland C. , Whitney Rae , Goldman Ralph F. , Griffin Patricia L. , Patt Donald I.
Published: December 2017

Adrenalectomized rats having intramuscular autotransplants of adrenocortical tissue regenerated from adrenal glands x-irradiated with 2000 r in vitro immediately prior to implantation did not survive as well nor gain weight as rapidly as did control rats with nonirradiated transplants. Moreover, at 14 days after operation they were more susceptible to histamine poisoning, water intoxication and exposure to cold, having little or no advantage over adrenalectomized rats in withstanding the first two stresses. The impairment in function was correlated with reduction in mass of secreting adrenocortical tissue, and presumably decrease in circulating level of corticosteroids, resulting from delayed regeneration of the x-irradiated transplants. Rats with intramuscular transplants regenerating in sites locally x-irradiated with 2000 r just before implantation of the glands withstood histamine poisoning at 14 days after operation as well as did their controls. Rats with subcutaneous transplants in the ears x-irradiated with 2000 r at 28 days after operation (established transplants) and tested 2 weeks later responded to exposure to cold like their controls.
Effect of Radiation on the Metabolism of Creatine
Authors: Anderson D. R. , Joseph B. J. , Krise G. M. , Williams C. M.
Published: December 2017

The rate constant for the exponential decrease in specific activity of urinary creatinine excreted after the injection of creatine-1-C14 in two dogs was found to be –0.0165. This rate was not significantly changed by 400 and 500 r of whole body x-radiation; no significant creatinuria was observed immediately following radiation at this dose level. The urinary output of creatine and creatinine was measured at 2 and 6 months in three rats which survived 1500 r of whole body Co60 gamma radiation and in three rats which survived 435 rep of mixed radiation (neutron to gamma ratio of 3:1). The average daily urinary creatinine excretion was depressed in the rats radiated with gamma rays at 2 and at 6 months; this creatinine depression was not found in the rats radiated with neutrons. The total urinary output of creatine and creatinine was not significantly changed at 2 months in the rats radiated with gamma rays, but was significantly depressed at 6 months; no change in total urinary output of creatine and creatinine was found in the rats radiated with neutrons.
Effect of Prolonged Cold Exposure on in Vitro Respiration and Anaerobic Glycolysis of Rat Liver
Authors: Hannon John P.
Published: December 2017

Liver slices were prepared from rats that had been exposed to cold (5 ± 1°C) for intervals of 2, 4, 6 or 9 weeks, and assays were made for respiratory rate and the rate of anaerobic glycolysis. The results of the respiration experiments indicated the first 4 weeks' cold exposure was associated with increasing qo2 values, whereas exposure longer than 4 weeks was associated with qo2 that returned toward the control value. The results indicated further that the exact nature of the substances being metabolized in the conventional tissue slice experiment was unknown. The results of the anaerobic experiments indicated the rate of anaerobic glycolysis decreased progressively as the duration of cold exposure was increased.
Thyroid Circulation in the Rabbit Including Arteriovenous Difference
Authors: Monkus Ellen F. , Reineke E. P.
Published: December 2017

Thyroidal I-131 clearance and arteriovenous difference, together with urinary excretion of I-131, were determined in 19 rabbits maintained for varying periods on a low iodine diet. Absolute blood flow was computed by dividing thyroidal I-131 clearance by AV difference. Thyroid cell heights were measured as an independent index of thyroid status. The rabbits were divided into two distinct groups on the basis of acinar cell heights: Group I with mean cell heights of 4.1–5.2 micra and group II with mean cell heights of 6.9–8.9 micra. Group I had a mean clearance of 0.43 gm blood/min. and a mean thyroid/urinary (T/U) ratio for I-131 of 3.1. The mean AV difference was 25%. Absolute and relative blood flows averaged 2.0 gm/min. and 6.1 gm/ min/gm thyroid, respectively. Group II had a T/U ratio of 40 and mean clearance of 4.3 gm/min. Mean AV difference was increased to 57%. Absolute and relative blood flows averaged 7.9 gm/min. and 22 gm/min/gm thyroid, respectively. All of the indices listed were significantly higher ( P = 0.02) in group II than in group I. Absolute thyroid circulation was significantly correlated with T/U ratio ( r = 0.87), but relative thyroid circulation was not. Relative blood flow was significantly correlated with mean acinar cell height ( r = 0.68), but absolute blood flow was not.
Plasma Proteins and Fat Transport in Dogs
Authors: Swank Roy L. , Fellman J. H.
Published: December 2017

The rapid injection of dog's chyle into recipient dogs causes the concentration of the plasma beta globulin, and, several hours later, the alpha globulin to increase. Simultaneously the plasma gamma globulins decrease. These changes are maximal 4–7 hours after injection and the plasma returns to normal in 7–24 hours. After injections of vegetable oil, emulsified in the dog's own blood plasma, more marked increases in the plasma alpha (also beta) globulins occur. This is followed by significant increases in the fibrinogen and gamma globulin. These changes remain for at least 7 days and repeated fat injections progressively exaggerate them. The gradual increase in whole blood viscosity in the dog which occurs after emulsified oil injections is associated with and probably due to the increased concentration of large molecular weight globulins and fibrinogen. Extraction of washed chylomicra with either ether or chloroform leaves a protein having an S20 = 4.4 and paper electrophoretic properties of alpha 1 globulins. Similar extraction of lipemic plasma and of whole chyle is followed by a marked decrease in alpha 2 globulin peak and a corresponding increase in the alpha 1 peak. These observations suggest that the protein component of the chylomicra in dogs is largely alpha 1 globulin.
Cardiovascular Hemodynamics Consequence to Crossed Circulation in the Dog
Authors: Roberson W. J. , Horvath Steven M.
Published: December 2017

Twelve experiments were conducted on anesthetized and paired dogs of similar weights subjected to unimpeded, unregulated crossed circulation. Shunts were made between the carotid arteries and external jugular veins and free flow allowed for 60 minutes or longer. Statistically significant changes occurred in the mean femoral arterial blood pressures, carotid shunt blood flow, heart rate, cardiac output, cardiac work, percentage of cardiac output flowing through the shunt and pulmonary systolic and diastolic pressures of one or both animals from their control values. The mean arterial blood pressure remained at control levels for several minutes and then dropped precipitously to hypotensive levels. The lowest mean pressures between 42 and 49 mm Hg occurred within the first 16.5 minutes of the open shunt phase with a gradual return toward control levels. The volume of blood flowing through the shunt was increased initially 250% above the control carotid blood flow, followed by a reduction in flow after 15 minutes; the volume flow at this moment was still double precross circulation levels. A secondary increase in the shunt blood flow occurred throughout the remainder of the open shunt phase. In general, the heart rates and peripheral vascular resistance were slightly elevated during the open shunt phase while cardiac output and work decreased below their control values. A marked and similar increase in the percentage of the cardiac output flowing through the carotid artery was observed in both animals. During the 60 minutes of the recovery period mean arterial blood pressure, cardiac output and work tended to return to control levels while the carotid artery blood flow and pulmonary systolic and diastolic pressure remained slightly below their control values.
Effect of Sympathectomy and Vagotomy on Carbonic Anhydrase Activity, Oxidative Phosphorylation, High Energy Phosphates Content and Electrolytes Content of the Gastric Mucosa
Authors: Yakushiji Takeshi , Kikuchi Tetsuya , Yamamoto Junichi , Kuriaki Kaname
Published: December 2017

Sympathectomy enhanced carbonic anhydrase activity, increased the rate of oxidative phosphorylation and the ATP and potassium contents of the canine gastric mucosa. Vagotomy was essentially without effect.
Glucose Penetration Into Liver
Authors: Cahill George F. , Ashmore James , Earle A. Scott , Zottu Sylvia
Published: December 2017

To further define the action of insulin on liver metabolism, studies were undertaken to determine whether the cell wall could be the site of action as has been proposed for muscle. Control rats and those injected with varying amounts of glucose were found to have a higher glucose concentration in liver water compared to plasma water with low plasma glucose levels and vice-versa with high plasma glucose levels. Radioactive glucose was freely distributed into total liver water in dogs whether the liver was taking up or producing glucose. Other compounds which entered rat liver cells were fructose, mannose, galactose, sorbitol, mannitol, glycerol and α-methyl glucopyranoside. Maltose, sucrose and raffinose were restricted to extracellular fluid. Alloxan diabetic rats likewise showed free equilibration of radioactive glucose between plasma and liver water. The free permeability of liver to glucose and other small carbohydrates suggests that insulin in liver alters intracellular enzyme functions and not permeability of the cell wall as in muscle.
Effects of Niacin and Vitamin C on Blood Sugar
Authors: Bera G. N. , Chowdhury J.
Published: December 2017

Intramuscular injection of niacin in normal rats induces hyperglycemia which lasts approximately 1 hour. In adrenalectomized rats niacin produces a hypoglycemia. Subcutaneous injection of vitamin C lowers blood sugar in normal and diabetic rabbits, the effect being pronounced when the blood level of vitamin C is high. The simultaneous administration of niacin and vitamin C produced a pronounced hypoglycemia. The rise in blood sugar normally produced by niacin is nullified if vitamin C is injected simultaneously or shortly thereafter. In both normal and diabetic animals, vitamin C injections produce an increase in liver glycogen. The vitamin C content of liver is lower in normal than in alloxan diabetic animals.
Intravenous Glucose Tolerance Test In Hypophysectomized Rats
Authors: Chernick Sidney S. , Scow Robert O.
Published: December 2017

Intravenous glucose tolerance tests were performed on normal and hypophysectomized rats that had been allowed to eat at will or were fed a constant amount by tube. The rates of removal of excess blood glucose ( k) were calculated. The k values for unoperated rats were the same regardless of the means of administration of food. The rate of removal of excess glucose was decreased in ad libitum-fed but not in tube-fed hypophysectomized rats. In the operated animals the value of k was not constant; it increased with time after administration of glucose load. Increasing the duration of fasting of operated tube-fed rats decreased the k; prior oral administration of glucose to hypophysectomized rats fed ad libitum increased the k. The lability of the intravenous glucose tolerance test in hypophysectomized rats is stressed.
Perfusion of the Isolated Adrenals in Situ
Authors: Hilton James G. , Weaver Davis C. , Muelheims Gerhard , Glaviano Vincent V. , Wégria René
Published: December 2017

A technique is described in which the circulation of the adrenal glands of the dog is completely isolated on the arterial side as well as on the venous side. With this technique the adrenal glands can be perfused in situ and, if desired, in vivo without any interruption of their blood supply and without any direct trauma. The adrenal glands may be perfused with the dog's own blood pumped by the dog's own heart (autoperfusion), or with the blood of another dog pumped by a mechanical pump. It was found that unless both recipient and donor dogs are hypophysectomized, the adrenal glands of the recipient dog are maximally stimulated and are not responsive to large doses of ACTH. If hypophysectomized animals are used, the perfused adrenals secrete small amounts of hydrocortisone and are responsive to very small doses of ACTH. This technique would seem to be an ideal means of studying the direct effect of any agent on the adrenal glands without the interference of other endocrine glands or other organs.
Effect of X-Irradiation on Bound Iron and Unsaturated Iron-Binding Capacity in Rabbits
Authors: Haley Thomas J. , Flesher Anna M. , Komesu Nathan
Published: December 2017

Acute whole body-x-irradiation produced a hyperferremia in rabbits. This effect reached its peak on the 4th day, at which time the iron-binding globulins were almost completely saturated. The radiation dose did not affect the iron-binding mechanism even when the globulins were saturated prior to irradiation because the saturation resulted in a prolongation of the period of irradiation hyperferremia. The results support the theory that irradiation hyperferremia is a result of decreased iron utilization by the bone marrow. There does not appear to be any relationship between radiation lethality and hyperferremia.
Induction of Renal Hypertension in Rats and Dogs by Potassium or Choline Deficiency
Authors: Grollman Arthur , White Fred N.
Published: December 2017

The maintenance of rats and dogs on a choline- or potassium-free diet for periods of 1–4 weeks after weaning results in the development of hypertensive cardiovascular disease. The rapidity with which hypertension develops and its severity is determined by the length of the period during which they are maintained on such diets and may be accentuated by unilateral nephrectomy, the substitution of 1% sodium chloride for the animal's drinking water, the administration of alcohol (in conjunction with choline deficiency) or by a combination of these procedures.
Effect of Arteriovenous Fistula on Mean Arterial Blood Pressure, Coronary Blood Flow, Cardiac Output, Oxygen Consumption, Work and Efficiency
Authors: Wégria René , Nakano J. , McGiff J. C. , Rochester D. F. , Blumenthal M. R. , Muraviev Tatiana
Published: December 2017

In the anesthetized dog, acute arteriovenous fistulae sufficient to increase the cardiac output by from 16 to 130% resulted in an increase in the coronary blood flow even in the presence of a definite and even marked drop in the mean arterial blood pressure. The arteriovenous fistulae also resulted in an increase of the cardiac work and oxygen consumption as well as the cardiac efficiency.
Effect of Catecholamines, l-Epinephrine and l-Norepinephrine on Coronary Flow and Oxygen Metabolism of the Myocardium
Authors: Feinberg Harold , Katz Louis N.
Published: December 2017

The effect of continuously infused intravenous l-epinephrine and l-norepinephrine (0.1–2.5 gamma/kg/min.) was determined in the open-chest, anesthetized dog prepared for measurement of total coronary flow. Coronary blood flow, myocardial oxygen availability and coronary venous oxygen content consistently increased after catecholamine administration despite wide fluctuations, above and below control values, in heart rate and mean aortic pressure at constant cardiac output. Thus, there was a significant decrease in the coronary arteriovenous oxygen difference after catecholamine administration. The increase in coronary flow and decrease in the coronary A-V oxygen difference were seen even when blood pressure and heart rate were lowered. It is concluded that the departure from the usual relationship between coronary flow and myocardial oxygen consumption is attributable to coronary vasodilatation. However, myocardial oxygen consumption is still the primary factor controlling coronary flow during catecholamine action.
Activation of Prothrombin
Authors: Landaburu Ricardo H. , Seegers Walter H.
Published: December 2017

In experiments with purified biothrombin, it was found that strong solutions of sodium citrate or protamine sulfate (0.1% w/v) or purified platelet factor 3 depress the esterase activity and leave the clotting power unaltered. Apparently a depression of esterase activity is beneficial for the autocatalytic activation of purified prothrombin. In protamine sulfate solution, prothrombin gradually becomes thrombin and the yield of thrombin is even higher than in 25% sodium citrate solution. Prothrombin also depresses the esterase activity of biothrombin, and itself serves as a substrate for the enzyme thrombin. When prothrombin becomes an inactive derivative or a substance refractory to being converted to thrombin in the presence of Ac-globulin, thromboplastin and calcium ions, it can nevertheless be changed to thrombin with the use of thrombin as a catalyst, just as was previously accomplished with the use of 25% sodium citrate solutions. Theoretically, a prothrombin derivative(s) can serve as substrate competitor for thrombin and thus be an accelerator of prothrombin activation, or the derivative, under appropriate conditions can itself give rise to thrombin. Thrombin as activator of prothrombin can account for all observed conditions of prothrombin activation. The discovery of thrombin as activator of prothrombin offers a simplified view of the entire blood coagulation mechanisms. Two equations can describe the basic events: Prothrombin(See PDF for Equation)Thrombin; Fibrinogen(See PDF for Equation)Fibrin. Other factors support the production and enzymic function of thrombin and these are called procoagulants. Opposed to these, and normally in exact balance, are those factors that hinder the production or function of thrombin and these are called anticoagulants. In the presence of thrombin prothrombin can change to thrombin without Ac-globulin. Plasma Ac-globulin changes to serum Ac-globulin in the presence of thrombin but not with esterase thrombin. Consequently, the depression of esterase activity does not impair the capacity of thrombin to make the beneficial alteration in Ac-globulin.
Respiratory Activity and the Hypothalamus
Authors: Redgate E. S. , Gellhorn E.
Published: December 2017

Lesions in the lateral hypothalamus produced by high frequency currents result in an immediate decrease in rate and/or depth of respiration in lightly anesthetized cats. The effect increases with the size and number of such lesions; even unilateral lesions are effective. The blood pressure and heart rate are decreased slightly at the same time. If the respiration declines markedly, compensatory regulations due to asphyxia occur which raise the blood pressure and restore respiration. Bilateral injections of barbiturates into the lateral hypothalamus are followed by a reversible reduction in respiratory activity. It is concluded that impulses from the lateral hypothalamus exert a tonic facilatatory action on the respiratory center.
Age Related Changes in Plasma Proteins of the Fetal Goat
Authors: Barboriak Joseph J. , de Bella Gregorio , Setnikar Ivo , Krehl Willard A.
Published: December 2017

Changes in the protein composition of the fetal plasma of the goat as related to the age of the fetus were followed by means of paper electrophoresis. Five protein peaks could be distinguished and they were tentatively marked as albumin, fetuin, alpha1, alpha2 and beta globulins. Practically no gamma globulins were detected. The plasma albumin relative concentration increased from 6% on the 46th day to 45% on the 135th day of gestation. The relative fetuin content decreased with the advancing age of the fetus. The percentage of alpha1, alpha2 and beta globulins did not change significantly during fetal development.
Nonspecific Protective Effect of Small Lead Shields Against Irradiation Death in the Rat
Authors: Bohr David F. , Rondell P. A. , Palmer L. E. , Bethell Frank H.
Published: December 2017

Rats subjected to 650 r whole body irradiation were protected and to about equal extent by shielding either skin or muscle tissue. Shielding both tissues virtually doubled the protection. It is suggested that this ability to protect against the lethal effects of whole body irradiation is not necessarily related to the primary physiologic function of the shielded tissue, but may be a potentiality of any unirradiated cell.
Strain Differences in Response to Whole Body Irradiation and Shielding Procedures in the Rat
Authors: Bohr David F. , Zippin C. , Rondell P. A. , Palmer L. E.
Published: December 2017

Over the past 3 years we have used 421 rats in studies of the protective effect of lead shields against irradiation death. Two strains of rats were used throughout these studies. The strain that was more sensitive to whole body irradiation was also the one more effectively protected by the shielding procedure. Previous work indicated that shielded tissues made some contribution to the irradiated animal which enhances its chances of survival. From the current study it is concluded that the strain in which the tissues are best able to make this type of contribution is also the one in which this contribution is most readily destroyed by irradiation.
Factors Affecting the Incidence of Atrial Fibrillation
Authors: Holland W. C. , Tinsley Betty
Published: December 2017

A study of fibrillation induced in isolated rabbit atria by stimulating at high frequencies (600–1200 cycles/min.) in presence of acetylcholine revealed it to be dependent on the ionic composition of the medium. The effects of varying the Na, K and Ca ion content of the bath fluid on the incidence of fibrillation are interrupted on the basis that fibrillation only begins at a time when the transmembrane flux of Na and K ions exceeds a critical rate. Evidence is presented that the initiation and maintenance of fibrillation are governed by separate physico-chemical processes. The onset of fibrillation results from a sudden transient increase in cell membrane permeability. This latter reaction sets off other biochemical processes which maintain the phenomenon.
Relation of Bradycardia and Blood Pressure of the Fetal Lamb in Utero to Mild and Severe Hypoxia
Authors: Reynolds S. R. M. , Paul W. M.
Published: December 2017

Fetal lambs of mostly 130–145 days gestation age, were subjected to hypoxia by having the ewe breathe 13%, 10% and 6% oxygen. The umbilical artery and umbilical veins were catheterized with the fetus still in utero along with the maternal carotid artery. Blood pressures and heart rates were recorded, as well as maternal respiratory movement through an intrapleural trochar. Samples of ewe arterial and fetal venous bloods were taken for O2 and CO2 tension analysis by the Riley method. With mild or moderate hypoxia, umbilical artery mean and pulse pressures generally increase; fetal heart rate may increase, decrease, or fluctuate. With severe hypoxia, mean and pulse pressures in the umbilical artery decrease along with the fetal heart rate. When periodic breathing occurred in the ewe, reciprocal effects on the ewe and fetal circulations were observed; as the ewe heart rate and blood pressure went up during apnea, the fetal heart rate and blood pressure went down and vice versa when respiratory movements were resumed. Bradycardia in its initial stages may be momentarily stopped by injection of atropine into the fetus. The critical O2 tension for depression of the fetal circulation is between 10–30 mm Hg. Bradycardia is not indicative of mild or moderate hypoxia; blood pressure improves with mild or moderate hypoxia; when blood pressure and heart rate both decline in severe hypoxia, it is indicative of fetal heart failure and imminent fetal death. The initial hypoxic bradycardia results from vagal activity since it can be blocked briefly by atropine and since the heart rate may fluctuate between beats from a slow to a fast rate. Fetal heart rate and blood pressure respond quickly to change of the gas content of the ewe's blood as demonstrated by changes occurring during periodic breathing in the ewe.
Mechanism of Action of Norepinephrine in Hemorrhagic Shock
Authors: Lansing A. M. , Stevenson J. A. F.
Published: December 2017

Twenty-nine dogs were subjected to a standardized hemorrhagic shock procedure, and various indices were measured in the succeeding 24 hours. During this period, 15 animals received intravenous l-norepinephrine, 0.2– 1.0 µg/kg/min. beginning immediately after the shock procedure. The survival rate of the control animals was 2/14, and of the treated 6/15. Norepinephrine infusion sustained the arterial pressure of the treated animals, not by increasing the peripheral resistance, but rather by maintaining the cardiac output. Since the decline in effective circulating plasma volume that occurred in the first 8 hours after the shock procedure was not prevented by norepinephrine, it is concluded that, in these doses, norepinephrine may exert its beneficial effect by a direct action on the heart. The increased oxygen consumption after the shock procedure in the norepinephrine-treated animals may have been due to a direct effect of the drug on metabolism.
Fate of Triglycerides and Phospholipids of Lymph and Artificial Fat Emulsions: Disappearance From the Circulation
Authors: McCandless Esther L. , Zilversmit D. B.
Published: December 2017

Artificial fat emulsions labeled in either triglyceride or phospholipid component were administered to unanesthetized normal dogs to determine the disappearance rates of the two lipids from the circulation. Similar experiments were carried out using lymph from donor dogs fed I131-triolein or P32-phosphate with unlabeled triglyceride. Triglycerides were found to be rapidly removed from the circulation whether they were administered as an artificial fat emulsion or as a physiological emulsion, lymph. On the other hand, the emulsifying agents, liver lecithin or lymph phospholipid, required several hours for removal from the circulation. Evidence is presented that the slow disappearance rate of chylomicron phospholipids cannot be accounted for by exchange with plasma lipoproteins and indicates a slow removal of chylomicra phospholipid from the circulating blood. These findings are discussed in reference to current concepts of the chemical structure of lymph chylomicrons and of particulate fat in an artificial fat emulsion.
Vitamin A Content in the Regenerating Liver of Rats
Authors: Liu C. H. , Ashton G. C. , Hays V. W. , Catron D. V.
Published: December 2017

In three experiments, partial hepatectomy was performed on 42 male rats weighing about 200 gm each, with excision of about 70% by weight of the liver. Then they were killed 1, 2, 4, 8 and 16 days after hepatectomy, respectively. The liver portion removed from each rat at the time of the operation was used as the corresponding control for the evaluation of change of the hepatic vitamin A content of the regenerating liver at killing. The concentration of the hepatic vitamin A decreased after partial hepatectomy. The decrease was about 30, 35 and 41%, at 1, 2 and 4 days, respectively, after the operation. Sixteen days after partial hepatectomy the average hepatic vitamin A concentration was 31% higher than the value at the time of operation. However, the value was much lower than that in the liver of the intact rat of the same age. Similar results were found when the partially hepatectomized rats were killed 21 days after operation. The vitamin A content in the kidneys of the operated rats also declined as the hepatic vitamin A decreased.
Effects of Altitude, Cold and Heat on Metabolic Interrelationships in Rats
Authors: Mefferd Roy B. , Hale Henry B.
Published: December 2017

Adult male Wistar rats were exposed for 3 months either to simulated altitude or to hot or cold environments, and comparisons were made during the final month using body weight, food and water intake, the 24-hour fasting urine volume, and the excretion of sodium, potassium, phosphate, magnesium, calcium, urea, uric acid, creatinine, taurine, histidine, glycine, alanine, valine, aspartic acid, glutamic acid, methionine and serine. Correlational analyses showed that many of the above-listed variables remained in constant association in the different environments regardless of the extent of their separate quantitative changes. Intergroup changes in the variable-relationships noted in certain of these environments may indicate either an incomplete acclimatization or an environmentally specific adaptation.
Action of Insulin on Distribution of Glucose Analogs in Eviscerated-Nephrectomized Dogs
Authors: Landau Bernard R. , Ship Arthur G. , Levine Herbert J.
Published: December 2017

Insulin increased the distribution of 2-deoxyglucose, 3-deoxyglucose and 2-deoxygalactose in eviscerated-nephrectomized dogs. 6-O-methylglucose was nonresponsive to insulin. The response of 3-O-methylglucose appeared dependent upon the blood glucose level. These results are interpreted as indicating that the stereochemical requirements of aldohexoses for insulin response does not require a hydroxyl group on either carbon 2 or 3 of the molecule, nor does it require a specific configuration of the hydroxyl on carbon 4. It is suggested from the behavior of the methylated analogs that the size rather than the functional nature of the group at carbons 3 and 6 is important in determining insulin responsiveness.
Degradation of Insulin-I131 by an Extract of Anterior Pituitary Gland
Authors: Narahara H. T. , Williams R. H.
Published: December 2017

When insulin-I131 was incubated at 37°C and pH 7.5 with an extract of beef anterior pituitary, the radioactive material was rendered more soluble in trichloroacetic acid (TCA). Electrophoretic analysis of the TCA-soluble reaction product revealed that it was not free iodide. The concept that pituitary extract might contain a system capable of attacking the insulin molecule was strengthened by the observation that the addition of nonlabeled insulin to the incubation mixture decreased the rate of degradation of insulin-I131. The degradative system of beef anterior pituitary extract was found to be nondialyzable and heat-labile. The degradation of insulin by pituitary extracts may help to explain the observation of other workers that such extracts can inactivate insulin in vitro.
Enhancement of Vitamin B12 Absorption by D-Sorbitol as Measured by Maternal and Fetal Tissue Levels in Pregnant Rats
Authors: Rice Edward G. , Herndon John F. , Van Loon Edward J. , Greenberg Samuel M.
Published: December 2017

Tissue vitamin B12 levels were determined in the blood, liver, kidneys, gastrointestinal tract and uteri and contents in pregnant and nonpregnant female rats following oral administration of three doses of radioactive vitamin B12 (Co60). Differences in radioactivity of tissues of animals administered Co60 vitamin B12 in water and in d-sorbitol at different stages of pregnancy were noted. d-Sorbitol administration significantly enhanced vitamin B12 absorption in both pregnant and nonpregnant rats. Gestation, but not d-sorbitol, causes an alteration of the tissue distribution pattern of the vitamin. As fetal growth progressed the fetuses obtained a large proportion of the absorbed B12 which would normally have gone to the maternal tissues. During growth of the total fetal mass from 3 to 30 gm the amount of B12 retained per gram of tissue remained fairly constant. The amount of B12 taken up by the fetuses was to a great degree controlled by the amount of the vitamin absorbed by or stored in the mother during gestation.
Body Temperature of Young Lambs
Authors: Hamdy A. H. , Weaver C. R.
Published: December 2017

The body temperatures of 37 Merino and Shropshire lambs were recorded for the first 100 days of life. Mean temperature of Merino lambs was found to be 102.8°F with a range of 100.2°– 104.0°F while the mean temperature of Shropshire lambs was 102.7°F with a range of 101.2°–104.4°F. There was no relation between the internal and atmospheric temperatures. Again, the correlation between the body and atmospheric temperatures within limited age groups was not statistically significant. The temperature of older lambs was less variable than that of younger lambs.
Hypothermia in the Rat, Hamster, Ground Squirrel and Pigeon Following Chlorpromazine
Authors: Hoffman R. A. , Zarrow M. X.
Published: December 2017

Body temperature changes induced by two dose levels of chlorpromazine HCl were compared in the rat, hamster, ground squirrel and pigeon. In addition, the effect of cold exposure was determined in the hamster. All three mammalian species showed a rapid decline in temperature by the first 2 hours following the injection of 10 mg/kg body weight of chlorpromazine, after which a gradual return toward normal was evident. However, a further decrease in body temperature occurred at the higher dose level of chlorpromazine (100 mg/kg body weight) and the degree of hypothermia varied with the species. The hamster appeared to be the most resistant to this compound while the ground squirrel was the least resistant. The female of the three mammalian species was less susceptible than the male. The combination of cold exposure and chlorpromazine in the hamster produced a decline in body temperature that was greater than that produced by either stressor alone. Again a sex difference was noted. The pigeon failed to respond to the drug in any degree comparable to that seen in the mammals. This was thought to be due to the lack of effect on respiration, an important thermoregulatory mechanism in the bird.
Effects of Hemorrhage on Blood Pressure Responses to Epinephrine and to Histamine
Authors: Hilton James G.
Published: December 2017

Effects of hemorrhage on blood pressure responses to epinephrine and to histamine were studied in dogs anesthetized with sodium pentobarbital. A series of graded doses of either l-epinephrine bitartrate or l-histamine diphosphate was given before and after hemorrhage, and the blood pressure effects of each dose of the administered drug were recorded. Amount of hemorrhage was determined as 10% of the experimental animal's Evans blue blood volume. Blood pressure records were analyzed in terms of minimum or maximum blood pressure attained, actual rise or actual fall in blood pressure and duration of primary blood pressure response before and after hemorrhage. The results showed that there is a significant change in the minimum and maximum blood pressures attained, but no significant change in the actual rise, actual fall or duration of primary response of blood pressure. The amount of change in minimum or maximum attainable blood pressure was directly related to the amount of change in blood pressure which resulted from the decrease in blood volume.
Quantitative Evaluation of the Circulatory Adjustment of Splenectomized Dogs to Hemorrhage
Authors: Chien Shu
Published: December 2017

Controlled, single hemorrhages were carried out in splenectomized dogs (5–49% of blood volume) and sympathectomized-splenectomized dogs (5–32% of blood volume). A linear relationship exists between the degree of hemodilution and the amount of hemorrhage in both groups. Sympathetic activity aids in the fluid replacement after hemorrhage. In the sympathectomized-splenectomized dogs, the relationship between arterial pressure and blood volume reduction seems to be nonlinear. Arterial pressure of the splenectomized dogs does not decrease until blood volume reduction is more than 10%. Thereafter it decreases linearly with increasing volume reduction which is still compatible with life. In hemorrhages between 10 and 40% of blood volume, the roles played by sympathetic activity and hemodilution in the maintenance of arterial pressure are of about equal importance. The increase in heart rate after hemorrhage has S-shaped relationship to both blood volume reduction and arterial pressure decrease in dogs with or without sympathetic nervous system. The maximum heart rate displayed by sympathectomized dogs after hemorrhage (about 120 beats/min.) is much less than that of the dogs with sympathetic system intact (about 215 beats/min.). The activation of sympathetic activity is not fully achieved immediately after hemorrhage.
Plasma Electrolytes of the Pregnant Ewe and Fetal Lamb
Authors: Kaiser Irwin H. , Cummings John N.
Published: December 2017

Plasma electrolytes were determined in blood samples from 65 ewes and 85 of their lambs at about 70, 88, 106, 124 and 142 days of gestation. Sodium concentration increased in both ewe and fetus as pregnancy progressed, although the fetus always had a lower concentration. Potassium increased over 50% in the fetus and exceeded the maternal concentration after the 106th day. Calcium-magnesium combined in the fetus always exceeded maternal concentrations. As a result there was a steady increase in total determined cations in both ewe and fetus. Chloride concentration tended to parallel that of sodium in both ewe and fetus. Bicarbonate and phosphate remained relatively constant. Maternal proteins decreased and fetal proteins increased as pregnancy progressed. Lactate was high in ewe plasma at 70 days and fell steadily toward term. It remained constant at a low level in the fetus. In the ewe, the determined anions decreased with advancing pregnancy until at term there was a deficit of over 10 mEq/l. In the fetus there was always a deficit of determined anions, increasing with pregnancy and paralleling the maternal values.
Transtubular Movements of Urea in the Doubly Perfused Bullfrog Kidney
Authors: Love John K. , Lifson Nathan
Published: December 2017

Carbon labeled urea, both C13 and C14, was used in the doubly perfused bullfrog kidney in an attempt to resolve the net secretion of urea into component unidirectional rates. Under the conditions of these experiments, the rates of net secretion of urea as calculated from clearance measurements considerably underestimate the total transport of urea in the secretory direction. It was calculated that reabsorption as well as secretion of urea occurred. The average value for the total reabsorptive movement was 2.1 mg/kg/hr., for total secretory movement 2.9 mg/kg/hr. The average net secretory movement was 0.83 mg/kg/hr. The influence of several factors on the interpretation of the results is discussed.
Influence of Diet on Glucose Tolerance
Authors: Uram J. A. , Friedman L. , Kline O. L.
Published: December 2017

Page 522: J. A. Uram, L. Friedman and O. L. Kline, "Influence of Diet on Glucose Tolerance." Table 1, yellow corn meal 2208 should read: yellow corn meal 208.
Effect of Bone Marrow-Spleen Injection After Fast Neutron Irradiation in Mice
Authors: Cole Leonard J. , Ellis Marie E.
Published: December 2017

Following exposure to midlethal and supralethal doses of 2 mev and 8 mev neutrons from the cyclotron, a single intravenous injection of fresh isologous bone marrow suspension containing 1 x 106 nucleated cells, or a single intraperitoneal injection of isologous infant spleen homogenate was given. At neutron doses (550–700 rep) which elicited 100% mortality by 8 days in the controls, injection of bone marrow had no beneficial effect on survival. Following neutron doses in the midlethal range (380–400 rep), bone marrow injection elicited a slight increase (relative to buffer-injected controls) in the percentage of mice surviving at 8 days—57% versus 35%. During the 9–14-day period, a smaller proportion of mice (as a percentage of 8-day survivors) died in the bone marrow-treated group, compared with the controls—18% versus 60%, respectively. The over-all 30-day survival was 23% for the marrow-treated mice, and 14% for the controls. At this dose level, furthermore, deaths occurred during the 3rd and 4th weeks postirradiation in the face of apparently adequate bone marrow regeneration, as judged histologically, and the time distribution of deaths was essentially the same whether marrow was administered or not. These data, in sharp contrast with those observed following lethal doses of x-rays in mice, imply that the deaths following 2 mev neutrons in the midlethal range involve a mechanism different from that of x-rays at comparable doses—possibly the consequences of a delayed or secondary intestinal injury.
Functional Refractory Period of Cardiac Tissues
Authors: Rosenblueth Arturo
Published: December 2017

In dogs anesthetized with pentobarbital, with the heart denervated, the adrenals ligated, and the S.A. node crushed, pairs of stimuli ( S1– S2) were applied to the auricle or ventricle, varying the delay between S1 and S2. When the auricle was stimulated, the following relations were measured: S1– S2: A1– A2; A1– A2; A2– V2; A1– A2; V1– V2. The corresponding curves for ventricular stimulation were also plotted. Calling R1 and R2 the responses at a given site, the S1– S1: R1– R2 curves usually showed a horizontal branch. This branch indicates that impulses stimulated at different moments in the refractory cycle may reach the recording site at the same moment of the cycle. A theorem is demonstrated which proves that the constancy of the R1– R2 interval cannot be explained merely on the basis of slowed conduction rate of R2, but implies that the impulse stops at some point in the conducting path. For A-A or V-V propagation this stop is due to delay in the initiation. For A-V or V-A propagation, the stop occurs at some site in the intermediate conducting tissues. The stop in these cases is due to the existence of a prolonged functional refractory period (F.R.P.).
Biliary Excretion and the Metabolism of Radioactive L-Thyroxine
Authors: Flock Eunice V. , Bollman Jesse L. , Grindlay John H.
Published: December 2017

Dogs excreted the same compounds in the urine after injections of radioactive thyroxine whether they were normal or had a biliary fistula or biliary obstruction. Dogs with biliary fistulas excreted more of the conjugate in the urine than did normal dogs. Dogs with biliary obstruction excreted the largest amounts of the conjugate and also showed increased levels of the conjugate in the blood. All the changes were minor, however, compared to those found after hepatectomy. No evidence was found for conversion of thyroxine to triiodothyronine or tetraiodothyroacetic acid, but the present studies would not exclude the possibility that these substances are rapidly transformed intermediates in the metabolism of thyroxine.