bluuebunny/crossref_metadata_2025 huggingface dataset:
Responses of the Rat to Thermal Radiation
Authors: Hardy J. D. , Stoll A. M. , Cunningham D. , Benson W. M. , Greene L.
Published: December 2017

Using the method of rapid measurement of skin temperature during exposure to known amounts of thermal radiation, the ‘thermal inertia’ or kpc product ( k = thermal conductivity, p = density, c = specific heat) was measured for the rat skin. An average kpc value of 84 ± 18 x 10–5 cal2/cm4/sec/°C2 was obtained for the lightly anesthetized animal. This value was independent of the intensity of the radiation, the method of exposing the skin; i.e., shaving, clipping, or depilating, and anesthesia. Administration of 200 mg/kg of azapetine phosphate, a potent adrenolytic agent, was accompanied by a marked drop in skin temperature (4–5°C), but no statistically significant change was observed in the kpc values when compared with the controls. Unanesthetized animals were exposed to high intensity thermal radiation and the animals' reactions observed. Two reactions could be identified, the skin twitch and the escape or withdrawal reactions, occurring at average skin temperatures of 45–46°C and 51–52°C, respectively. A possible correspondence of these reactions to those previously observed to occur in man at these temperatures; i.e., pain threshold and wince threshold, was noted.
Mechanisms of Respiratory Stimulation During Hemorrhage
Authors: Schopp Robert T. , Gilfoil Thomas M. , Youmans William B.
Published: December 2017

The immediate effects of severe hemorrhage on respiratory rate and amplitude were determined in dogs before and after bilateral vagotomy and isolation of the carotid sinuses. The animals were anesthetized with morphine (3 mg/kg) intramuscularly and sodium pentobarbital (15 mg/kg) intravenously. The sino-aortic denervated animals showed no respiratory responses to 1–2 mg of sodium cyanide. Most of the animals showed immediate respiratory stimulation in response to hemorrhage before denervation, and in a large percentage of these the stimulation still could be elicited by hemorrhage after sino-aortic denervation. The rapid onset of the stimulation in the denervated animals and the fact that slow withdrawal of blood to produce a certain level of hypotension caused less stimulation than rapid withdrawal would indicate that decreased blood flow through the respiratory center may not be the basis for the response.
Volitional Activity Response of Rats to Partial-Body X-Irradiation
Authors: Jones D. C. , Kimeldorf D. J. , Osborn G. K. , Castanera T. J. , Rubadeau D. O.
Published: December 2017

Shielding of the abdomen during x-irradiation was used to test the hypothesis that the initial decrease in the volitional activity of rats observed after whole-body x-irradiation is related primarily to irradiation of the abdomen. Exposure of the abdomen to 200 r, or of the remaining half of the body to 200 or 600 r did not result in a significant depression in activity. When the abdomen was exposed to 600 or 750 r, however, a depression in activity was observed, with a minimum on the 3rd day postirradiation, followed by increasing activity. When animals were exposed to relatively high doses (1500 or 2000 r) with the abdomen shielded, or with only the head exposed (1500 r), there was an immediate depression in activity on the 1st day postirradiation, then a transient increase in activity to values equal to or well above control levels, followed by a rapid decrease below control activity, and then by increasing activity. The transient increase above control activity was duplicated by pair-feeding nonirradiated animals to the head-exposed group. It appears that the initial decrease in volitional activity may be mediated by altered gastrointestinal function, particularly with respect to the 3rd day postirradiation. In abdomen-shielded or head-exposed animals subjected to higher doses of x-rays, the transient rise in activity appears to be related to restricted food intake, probably as a result of radiation damage of the oral mucosa. The subsequent depression in volitional activity in these animals may be related to central nervous system injury.
Indicator Recirculation as a Limiting Factor of Indicator Dilution Techniques
Authors: Gerst Paul H. , Taylor Carolyn , Peterson Lysle H.
Published: December 2017

Short injections of Evans blue dye were made into the aortic root, pulmonary artery and femoral vein of dogs under normotensive and hypotensive conditions. The time intervals between the initial appearance of the indicator at the arterial sampling site and its first reappearance at the site (‘reappearance time’) were determined. Indicator concentration levels were measured simultaneously at the aortic root and femoral artery during the period of each injection. After the aortic root injections the indicator was rapidly cleared at the sampling sites so that the onset of recirculation was directly detectable from the time-concentration curve. Following pulmonary artery and femoral vein injections reappearance time was derived by the Hamilton semilogarithmic extrapolation procedure and the mean values were compared for reappearance time determined directly and indirectly. Under normotensive conditions it was found that the onset of recirculation can be adequately approximated by the Hamilton procedure when short injections are made into the pulmonary artery, but this approximation becomes less reliable in hypotension. When indicator is injected into a peripheral vein, the arterial time-concentration curve becomes so distorted that the true onset of recirculation cannot be detected by the Hamilton method. For the same injection, the mean values for reappearance times obtained at the femoral artery sampling site were greater than those obtained at the aortic root sampling site.
Thermochemical Efficiency of Growth in Rats
Authors: Mayer Jean , Vitale Joseph J.
Published: December 2017

A simultaneous study of changes in food intake and body composition during the 3 months of postweaning growth was undertaken on three large groups of albino rats fed semi-synthetic diets containing, respectively, 10, 25 and 60% protein. The results show a remarkable similarity of percentage of body weight represented by protein during the whole growth period for the three groups and constancy within each group. The thermochemical efficiency (ratio of calories deposited to calories ingested) was constant from weaning to puberty and particularly so on the diet with the protein content most favorable for growth (25%). The thermochemical efficiency, ratio of calories deposited to calories ingested, was approximately constant from weaning to puberty, on optimal diets and high protein diets, declined somewhat earlier on a low protein diet.
Mechanism of Insulin Hypersensitivity in the Hypophysectomized Dog
Authors: Wall J. S. , Steele R. , de Bodo R. C. , Altszuler N.
Published: December 2017

Following the intravenous injection of glucagon-free insulin into unanesthetized hypophysectomized dogs in the postabsorptive state, changes in the rates of glucose outflow from the plasma into the tissues and glucose inflow into the plasma from the liver were determined. By the use of C14 glucose, these flow rates were determined simultaneously while the plasma glucose concentration was changing. In the hypophysectomized dog, the same amount of insulin caused a greater increase in outflow from the plasma than in the normal dog, the duration of the period of increased outflow was not significantly longer. The liver of the hypophysectomized dog failed to release enough glucose in response to the induced hypoglycemia to restore the plasma glucose concentration promptly to the preinsulin level, whereas the liver of the normal dog responded readily. Because of the greater outflow of plasma glucose and inadequate inflow of glucose and the lower initial plasma glucose concentration, insulin causes a more severe and prolonged hypoglycemia in the hypophysectomized animal. The insulin hypersensitivity of the hypophysectomized dog may thus be attributed to two separate and perhaps equally important factors: a) a small amount of injected insulin results in a greater increase in the rate of plasma glucose uptake by the tissues than in the normal animal, and b) the hypoglycemia in the hypophysectomized dog is less effective in bringing about the release of sufficient amounts of glucose by the liver than in the normal one.
Hemodynamic Effects of Infusions of Epinephrine and Arterenol in Normal and Shocked Dogs
Authors: Collier H. Duane , Meyers Frederick H. , Schmitt G. H.
Published: December 2017

Levarterenol and l-epinephrine were infused into dogs and the effect on cardiac output and other measurements derived by the dye dilution technique were observed. In contrast to epinephrine, arterenol decreased or left unchanged the cardiac output, suggesting that there is not a species difference between dog and man and that arterenol and epinephrine are qualitatively different in their cardiovascular effects. In previous studies which disagree with this conclusion arterenol was administered by a rapid intravenous injection. The changes in cardiac output correlated well with the changes in total peripheral resistance, and the rise in peripheral resistance induced by arterenol is suggested as the factor which in the intact animal modifies the positive inotropic effect of arterenol apparent in isolated hearts. Circulating plasma volume, intrathoracic blood volume and cardiac output also rose and fell together. No difference in response to the two agents was apparent between normal dogs and those in which cardiogenic shock had been induced.
Bleeding Volume in Splenectomized Dogs
Authors: Deniz Nurettin , Gregersen M. I.
Published: December 2017

Acute total bleeding volume was measured several times in succession in the splenectomized dog utilizing an apparatus which records the bleeding within ±1% and facilitates rapid replacement of the collected blood. Blood volume was determined either with T-1824 alone or by simultaneous measurements with T-1824 and P32. In a group of 10 experiments in each of which the acute total bleeding test was carried out six times during 1.5 hours, the maximal variability between two successive bleeding volumes was ±8%. The mean difference between the first and sixth bleeding volumes was only 1.6%. The blood volume after the six successive bleeding tests was on the average 17% lower than before. When the values are corrected for blood lost in samples, etc., there is an unexplained average deficit of 12%. Since the bleeding volume remained fairly constant there was an apparent change in the relation between the bleeding volume and blood volume. The average initial bleeding percentage (first bleeding vol/ initial blood vol. x100) was 56.9, whereas the final bleeding percentage (6th bleeding vol/ final blood vol. x100) was 68. Among the various attempts to alter the bleeding volume, such as change in the bleeding rate, venous bleeding, intravenous injection of adrenaline, etc., only vagotomy and increase in plasma volume changed the bleeding volume beyond the variability observed in the standard bleeding series.
Alterations in Tissue Plasma Volume With Nembutal Anesthesia
Authors: Friedman J. J.
Published: December 2017

Effect of Nembutal administration on tissue plasma volume was determined in mice. Following the administration of Nembutal the circulating plasma volume increases from 1.1 ml to 1.3 ml. The plasma volume of the liver, kidney, spleen, lung and intestine exhibit an increase of about 35, 80, 85, 15 and 40%, respectively. The plasma volume of the skin displays a reduction of about 15%, while that of muscle reveals no significant change. These alterations in tissue plasma volume were not the result of changes in the capillary permeability to or the rate of metabolism of the injected radioiodoalbumin tracer.
Utilization of Calories From Alcohol and Wines and Their Effects on Cholesterol Metabolism
Authors: Morgan Agnes Fay , Brinner Lisa , Plaa Colleen B. , Stone Marcia M.
Published: December 2017

The utilization of calories for growth by young rats given an adequate diet, free access to drinking water and supplements of 15 or 20% alcohol solutions or wines of the same alcohol concentration was equal to that of rats receiving no alcohol if the alcohol calories were calculated as 75% physiologically available. When no additional water was given along with the alcohol and wine solutions or when water intake was restricted to the amount taken by the alcohol groups, the intake of diet and growth were at once decreased about equally in the water restricted, wine and alcohol groups. When 1% cholesterol was added to the diet all the rats grew better than on the basal diet and water restriction had less unfavorable effects. The liver fat of the alcohol groups was higher than that of the others on both basal and cholesterol diets. Both liver and adrenal cholesterol were much increased by the exogenous cholesterol in all groups but least in the wine fed animals. Hamsters under similar conditions were little affected by water restriction, but growth was decreased on the cholesterol diet and grossly fatty livers developed containing about half the lipid content as cholesterol. Serum cholesterol was much increased, least in the wine-fed groups. Restriction of water intake by rats given alcohol solutions appears to account for most of the effects of chronic alcohol ingestion heretofore reported.
Metabolism of Glycerol and Similar Compounds by Bull Spermatozoa
Authors: White I. G.
Published: December 2017

Actively motile washed bull spermatozoa metabolize glycerol aerobically producing lactic acid and material estimating as fructose. This process is accompanied by increased O2 uptake and decreased aerobic fructolysis. Dihydroxyacetone, but not phosphoglycerol, is oxidized at a similar rate and lactic acid is formed. It may be an intermediate of glycerol breakdown. Sorbitol is also oxidized by washed bull spermatozoa producing lactic acid and material estimating as fructose. Glycerol and sorbitol combined yield fructose in amounts greater than their separate effects.
Esterolytic Enzymes in Dog's Serum, Liver and Pancreas
Authors: Katz S.
Published: December 2017

The esterolytic enzymes of fresh extracts of liver, pancreas and serum of dogs have been studied, using α-naphthyl butyrate, caprylate and laurate as substrates. Eserine salicylate, sodium taurocholate, potassium fluoride, sodium arsanilate, di-isopropylfluorophosphate (D.F.P.), diethyl- p-nitrophenylphosphate, E600, and quinine hydrochloride were employed as inhibitors or accelerators. In the liver, the presence of an esterase proper and some pseudocholinesterase has been demonstrated. In the serum, a considerable amount of pseudocholinesterase and a pancreatic type of lipase were found. The presence in the pancreas of an esterase proper is discussed.
Urinary Purine Excretion in the X-Irradiated Dog
Authors: Jackson Kenneth , Entenman Cecil
Published: December 2017

Urinary excretion of purine bases by the dog following whole-body x-irradiation was studied. Ion exchange chromatography with Dowex-50 was used to measure uric acid, xanthine, hypoxanthine, guanine, 7-methylguanine and adenine. Changes in the excretion of uric acid and xanthine were noted during the first 24 hours following irradiation. Uric acid excretion was increased following doses between 150 and 500 r. Xanthine excretion increased markedly following superlethal doses but not after midlethal doses. Total purine excretion (allantoin plus uric acid) was increased slightly following irradiation and the degree of the increase was not related to the radiation dose.
Interrelations During Renal Tubular Reabsorption in the Dog Among Several Anions Showing a Sensitivity to Glucose and Phlorizin
Authors: Cohen Julius J. , Berglund Fredrik , Lotspeich William D.
Published: December 2017

In the course of studies of reabsorption by the kidney tubule, it was noted that phlorizin and glucose change the rate of reabsorption of AcAc, SO4 and PO4. Phlorizin raises, while glucose depresses, the Tm for each of these ions. The effects of glucose and phlorizin on AcAc reabsorption were small, difficult to produce, and showed a tendency to recover. In contrast, the effects on SO4 and PO4 reabsorption were marked, easy to produce and showed no tendency to recover. It was thought that the molar rates of reabsorption might be determinants, and this in turn might be a measure of their relative affinities for a common reabsorptive path. A study of the interrelations of the three anions during maximal rates of reabsorption revealed that no such simple relationship exists. In an attempt to separate further the three transport mechanisms, the effect of the anions, NO3 and SCN on Tmacac, Tmso4 and Tmpo4 were studied and again no consistent reabsorptive pattern was discovered. The data point to net transport mechanisms which are in part shared and in part separate for each of the three anions.
Insulin and Tissue Distribution of Pentose in Nephrectomized Cats
Authors: Sacks Jacob , Bakshy Stanley
Published: December 2017

A comparison has been made of the ‘pentose space’ and ‘chloride space’ of various tissues in the nephrectomized cat injected intravenously with various pentoses, and of the effect of insulin injection on the pentose space. The four pentoses tested, d- and l-arabinose and D- and L-xylose, were found to pass readily into the intracellular compartment of liver. With this exception, and the apparent failure to penetrate the blood-brain barrier, d-arabinose and l-xylose, which have steric configurations about carbon atoms 1, 2 and 3 opposite to that of D-glucose, showed purely extracellular distribution which was not affected by insulin. In the absence of exogenous insulin, extracellular distribution of L-arabinose and D-xylose was found in lung, intestine, skin, spleen and muscle; under these conditions brain and heart showed partial penetration of these sugars into the intracellular compartment. The injection of insulin resulted in partial intracellular penetration into muscle, increased penetration intracellularly in brain and heart, and was without apparent effect on the other tissues analyzed. The findings are discussed in terms of the postulate of Levine that insulin acts to facilitate the transfer across the cell membrane of glucose and of those sugars with the same steric configuration as D-gluclose about carbon atoms 1, 2 and 3. It is concluded that if the mechanism of transport of glucose across the cell membrane is the same as that of transport of these pentoses, then the entry of glucose into the cell interior precedes any phosphorylation reaction.
Extensibility of Skeletal Muscle Undergoing Reinnervation
Authors: Thomson J. D.
Published: December 2017

Changes in the extensibility of rat gastrocnemius muscles resulting from crushing the sciatic nerve, and determined from static passive tension curves, were followed from 12 to 70 days after the lesion. Paralyzed muscle became progressively more resistant to stretch until the 21st day (experimentals averaging 235% above control level), after which it became less resistant to stretch and leveled off at 56 and 70 days (about 56% above control level). Attempts were made to correlate extensibility changes with other previously determined changes in gastrocnemii denervated by sciatic crushing. It is concluded that changes in extensibility are probably not due to: condensation of intracellular material due to decrease in muscle cell diameters; nor to changes in nonmuscle cell phase: muscle cell phase ratios; nor to changes in amount or arrangement of collagen fibers in the connective tissue. Loss of extensibility during atrophy and increased extensibility during reinnervation and recovery may be due either to changes in tendon extensibility or to changes in muscle cell extensibility, or to both. Changes in the muscle cell may be due to stiffening of muscle cell protoplasm by lowered metabolic activity, or (more probably) to lack of mechanical activity, allowing a ‘setting’ of the thixotropic muscle cell protoplasm. Recovery of normal extensibility through reinnervation may be due to an increased metabolic rate, or (more probably) to a mechanical stirring up of the protoplasm on resumption of muscular activity.
Summation of Potentials in the Chicken Electroretinogram
Authors: Crampton George H.
Published: December 2017

An electroretinogram was found only for the first flash of a series of flashes alternating between two separate locations on the exposed chicken retina. This was still true when a septum separated the two locations, therefore, excluding the possibility that nonfocal light might prevent successive activities by providing a constant illumination of the entire retina during the alteration of exposures. Further observations showed that the retinal areas were not inhibited, but were continually active and that with certain electrode placements and exposure rates, electrical summation concealed the individual contributions of each focal area.
Histidine Decarboxylase of Rat Stomach and Other Mammalian Tissues
Authors: Schayer Richard W.
Published: December 2017

With minute quantities of C14 l-histidine as substrate, rat stomach histidine decarboxylase shows a far higher activity than that from any other mammalian organ tested. Its maximum activity is ph 7.2. The maximum activity of rabbit kidney histidine decarboxylase is 8.0. Although the activity of the latter is greatly enhanced by benzene, rat stomach histidine decarboxylase activity is strongly inhibited by benzene. It is concluded that there are at least two mammalian enzymes with the same specificity which have major differences in molecular configuration. Studies of some properties of histidine decarboxylase are presented. Histidine decarboxylase activity of rat stomach drops markedly as early as 1 day following hypophysectomy. No comparable drop follows adrenalectomy.
Effects of Low O2 on Intestinal Blood Flow, Tonus and Motility
Authors: Bean John W. , Sidky Mahmoud M.
Published: December 2017

Effects of low O2 on intestinal blood flow were studied in blood perfused segments of dog intestine, 1) completely isolated and the low O2 administered by perfusion with hypoxic heparinized dog blood, or, 2) completely isolated except for extrinsic nerves and the low O2 administered either as in 1 or by respiratory gas mixtures via trachea. The local administration of low O2 (10–7%) to either preparation 1 or 2, increased intestinal blood flow remarkably. This, in the absence of any changes in intestinal tonus or motility, must be ascribed solely to dilatation of the intestinal vasculature per se which commonly predominates over the reflexogenic and/or centrogenic vasoconstrictive influence of low O2. Local histotoxic anoxia (0.3 ml of a 1% solution of NaCN) evokes effects similar to those of 7% O2. Low O2 can also prominently affect intestinal blood flow indirectly, a) by its action on intestinal tonus whereby it may enhance or completely nullify the effects of vasodilatation per se; and b) by its depressive action on the rhythmic intestinal contractions and their propulsion of intestinal blood. In passing through the intestinal vasculature the blood acquires potent vasodilatatory properties which must be ascribed to some ‘substance,’ other than CO2 or low O2, whose release into the blood is apparently facilitated by low O2. The data indicate that the intestine contributes to the reflex chemical control of breathing.
Measurement of Blood Volumes in the Splanchnic Bed of the Dog
Authors: Horvath Steven M. , Kelly T. , Folk G. E. , Hutt B. K.
Published: December 2017

Measurements of the distribution of blood volumes between the splanchnic and peripheral beds of dogs have been made. The splanchnic blood volume was found to be 21% of the total blood volume. The fractionation of the splanchnic blood volume between hepatic, splenic and mesenteric beds indicated that these contained approximately 30, 30 and 40%, respectively. There were certain difficulties which precluded precise measurement of the splanchnic fractions.
Relationships Among Stroke Work, Contractile Force and Fiber Length During Changes in Ventricular Function
Authors: Cotten Marion deV. , Maling Harriet M.
Published: December 2017

There is a linear relationship between ventricular contractile force and ventricular stroke work during changes in either atrial or aortic pressures and during the changes produced by l-norepinephrine. There is also a direct relationship between the contractile force or stroke work and the end diastolic length of the segment of ventricular muscle between the two points of attachment of a heart-lever system employed to measure the contractile force. There was no consistent relationship between the stroke work or contractile force and the systemic output or stroke volume. The relative merits of measurements of contractile force and stroke work in determining changes in ventricular contractility under a variety of conditions are discussed.
Ventricular Excitability and Refractoriness in the Hypothermic Dog
Authors: Angelakos E. T. , Laforet E. G. , Hegnauer A. H.
Published: December 2017

Measurements of ventricular exctiability through the entire cardiac cycle of the dog under progressive hypothermia show that the ventricular refractory period (measured as absolute, total or functional refractory period) is greatly prolonged. This effect is not secondary to the changes in heart rate since normothermic animals with surgical A-V block having heart rates similar to those obtained under hypothermia do not show any great prolongation in the ventricular refractory period. At heart temperatures ranging from 38° to 23°C there is no significant alteration in the diastolic excitability of the ventricle. The rate of recovery of diastolic excitability and the response latency were greatly prolonged as reflected in the marked increase in the duration of the relative and functional refractory periods. It is suggested that the increased susceptibility of the hypothermic myocardium to ventricular fibrillation may be related to the observed changes in the rate of recovery of excitability.
Ventricular Excitability in the Unanesthetized Dog and Its Modification by Pentobarbital Anesthesia
Authors: Laforet E. G. , Angelakos E. T. , Hegnauer A. H.
Published: December 2017

Cardiac excitability and refractoriness were determined in the unanesthetized dog via intrajugular electrodes in one group, and chronically implanted electrodes in another. The TRP in such dogs averaged 39% of the driving cycle, the FRP 42% and the ARP 32%. The intraperitoneal administration of pentobarbital resulted in small but consistent increments in these parameters, the TRP in anesthetized animals averaging 49% of the cycle, the FRP 52% and the ARP 40%. The diastolic threshold and RRP were unaltered. It is apparent that in ventricular excitability studies conducted under pentobarbital anesthesia there occur small but consistent modifications of the refractory period, cognizance of which should be taken when evaluating data obtained under these conditions.
Effect of Certain Steroids on Metabolic Rate of Hyperthyroid Rats
Authors: Doisy R. J. , Lardy H. A.
Published: December 2017

The effects of certain steroids on the elevated basal metabolic rate (BMR) associated with thyrotoxicosis were investigated. Under our experimental conditions the adrenal cortical hormones had no effect, whereas large doses of estrogenic hormones caused marked depressions of the elevated BMR of hyperthyroid male rats. This antagonism to the calorigenic action of the thyroid hormones was demonstrable also in adrenalectomized and adrenalectomized-thyroidectomized rats. It would appear that this antagonism between the estrogenic and thyroid hormones is not mediated via the pituitary, adrenal or thyroid glands.
Fixed Coupling and Short P-R Interval Induced in the Dog by Stimulation of the Sympathetic Nervous System
Authors: Walker Sheppard M.
Published: December 2017

Injection of 0.06–0.12 ml/kg of m/6 mixture of monobasic and dibasic potassium phosphate (ph 7.6) into the cisterna magna of barbitalized dogs increases the blood pressure 50–100%, increases the heart rate 20–80%, and induces cardiac arrhythmia. The effects of strong stimulation of the sympathetic nervous system, thus demonstrated, were studied in dogs with and without the vagi intact. Stimulation of the sympathetic nervous system in vagotomized dogs induces scattered ectopic ventricular beats, ventricular tachycardia and bigeminy. The bigeminy usually appears as an alternation of a normal sinus beat with an abnormal ventricular beat showing a short P-R interval and a prolonged QRS complex. This abnormal beat resembles the aberrant ventricular beat observed in the Wolff-Parkinson-White (WPW) syndrome. However, it is shown, by peripheral vagal stimulation, that the abnormality of the QRS complex is due to an ectopic ventricular impulse which usually fuses with a sinus impulse. Vagal stimulation inhibits the sinus impulse without changing the interval between the ectopic ventricular impulse and the preceding normal beat. In this way fixed coupling of the ectopic ventricular impulse with the preceding beat is established as the mechanism of the bigeminy.
Selective Depletion of Rat Aorta Potassium by Small Pressor Doses of Norepinephrine
Authors: Daniel Edwin E. , Dawkins Oswald , Hunt J.
Published: December 2017

Intravenous norepinephrine (1.0 µg/kg body weight) produced a strikingly uniform pressor effect in rats. The average blood pressure rise was 54 mm Hg, the peak rise occurred in less than 20 seconds, and the blood pressure returned to baseline in about 2 minutes. The aorta was rapidly depleted of potassium (15–18%) by the norepinephrine injection, depletion occurring within 20 seconds (time required for exsanguination) after the peak of the pressor effect and persisting throughout the period of the pressor response. Aorta sodium concentration did not increase concomitantly either in time or in quantity. No other tissue studied (stomach muscle, left ventricle, psoas muscle) showed a parallel alteration in electrolytes. Therefore, injections of norepinephrine appear to selectively affect permeability of vascular smooth muscle to potassium.
In Vitro Metabolism of Hydrocortisone in Tissues of the Adult Rat
Authors: Brown J. H. U. , Anason Atalante , Jacobs Julian
Published: December 2017

Various tissues of the rat were tested for ability to metabolize hydrocortisone from a Krebs-Ringer solution. Whole slices, homogenates and subcellular fractions were tested separately and under various conditions. The liver is capable of handling large amounts of steroid and of degrading both the A-ring and the sidechain. Other tissues are capable of metabolizing smaller quantities of hydrocortisone. Pretreatment of the animal influences the rate of metabolism of steroid by the liver. Administration of cortisone, or thyroxine, increases the ability of the liver to metabolize steroid; hypophysectomy or thyroidectomy reduces the rate of metabolism. The proper use of inhibitors permits the metabolism of either the sidechain or the A-ring selectively. A-ring metabolism is inhibited by DPN, PCMBA, dehydroascorbic acid and DPNH; it is accelerated by TPNH. Metabolism of the sidechain is accelerated by DPN, nicotinamide and TPNH. Metabolism of steroids occurs readily in the microsome fraction of liver and in the acidophilic granules of the pituitary. In the pituitary the fraction containing ACTH was also the fraction metabolizing most of the steroid sidechain.
Organization of Central Respiratory Mechanisms in the Brain Stem of the Cat: Genesis of Normal Respiratory Rhythmicity
Authors: Wang S. C. , Ngai S. H. , Frumin M. J.
Published: December 2017

This investigation was designed primarily to study three closely related questions about rhythmic breathing: a) how is apneusis (apneustic respiration) initiated and modified? b) Is the isolated medulla oblongata capable of producing rhythmic respiration? c) What mechanism generates the rhythm of normal breathing? The changes of respiratory pattern were studied in 131 mid-collicular decerebrate cats following serial transections of the brain stem at various levels, vagotomy and elimination of other peripheral receptors. a) It is concluded that a tonically active pontile center produces apneustic respiration, is anatomically and functionally distinct from the medullary inspiratory center, and is almost certainly not a part of the reticular facilitatory system. Afferent impulses from the carotid receptors may influence but do not initiate apneusis. b) The isolated medulla can maintain rhythmic respiration without the influence of spinal or vagal afferents but only under special conditions. However, the medullary respiratory centers are not the pacemakers for normal respiration. c) A new schema is proposed tentatively for the neural organization of normal respiratory rhythmicity. It is suggested that in normal respiration the rhythm originates in the pontile apneustic center with periodic modulation by inhibitory impulses from the pulmonary stretch receptors in the vagus and from the pneumotaxic center in the rostral pons.
Respiratory Response of Anesthetized Dogs to Progressive Anemic Hypoxia
Authors: Hull Wayland E.
Published: December 2017

Breath-to-breath analyses of air-flow responses of lightly anesthetized dogs to progressive anemic hypoxia by hemodilution or by breathing dilute carbon monoxide in air reveal only moderate changes in pulmonary ventilation. However, tidal volume undergoes progressive diminution, the alveolar ventilation remaining normal or slightly above normal by the concurrent increase in breathing rate. Despite the increase in breathing rate, hypoventilation and respiratory failure ensue when but 20–30% of the blood oxygen capacity is present. Administration of oxygen of high concentration to severely hypoxic dogs increases tidal volume, usually slowing the rate. The experimental method described lends itself to the study of factors which regulate and control pulmonary ventilation in the absence of chemoreceptor activity and when diminished blood oxygen capacity is the primary disturbing factor.
Cardiac Depressant Effect of CO2 and Its Reversal
Authors: Nahas Gabriel G. , Cavert H. Mead
Published: December 2017

Acute myocardial failure is observed when the denervated heart-lung preparation is rendered acidotic by increasing abruptly above 5% the CO2 concentration in a respiratory gas mixture of CO2 and O2. Evidences of this failing state include increased vena caval and left atrial pressures, decreased aortic pressure, diminished cardiac output against a constant resistance and acute cardiac dilatation. After production of acidotic failure by administration of 15% CO2 for 3–5 minutes (arterial ph = 7.14 ± 0.05, output negligible), values for these variables (with the exception of ph) can be returned to control levels by injecting 4 µg/min. of adrenaline or noradrenaline. Furthermore, the signs of CO2 failure do not appear if the adrenaline infusion is begun concomitant with high CO2 ventilation. These results were interpreted as indicating that in the intact dog, cardiac tolerance to hypercapnia may be the result of a stimulation of the sympatho-adrenal system, which counteracts the negative inotropic effect of CO2 on the myocardium. Reversal of CO2-induced failure was also observed within 5–10 minutes after injection of 0.1 mg of acetyl strophanthidin.
Effect of Acute Anoxia on the Glutamic Oxalacetic Transaminase Content of the Myocardium of the Rat
Authors: Merrill J. M. , Lemley-Stone Janet , Meneely George R.
Published: December 2017

Transaminase activity in tissues and serum was determined in a group of rats subjected to anoxia and in a control group of animals. There was a 27% decrease in the transaminase activity of the anoxic myocardial tissue without any appreciable change in serum activity. Other tissues which were studied showed that anoxia produces varying decrements in transaminase activity. In vitro studies of tissue taken from anoxic animals indicate that the loss of transaminase activity is not caused by loss or destruction of its coenzyme, pyridoxal phosphate.
Accumulation of Pyruvate in Phenylhydrazine-Treated Avian Red Blood Cells
Authors: Geber William F. , Rostorfer H. H.
Published: December 2017

Loss in oxygen capacity which occurs when avian erythrocytes are treated in vitro with phenylhydrazine is completely or partially restored (depending on the initial concentration of phenylhydrazine) on incubation of the cells for 1 hour in the presence of glucose or lactate under anaerobic conditions. Restoration in oxygen capacity is always accompanied by a proportional accumulation of pyruvate (the proportion differs for each substrate) which bears the same relationship to the gain in oxygen capacity as that found for the metabolic reduction of methemoglobin by the avian erythrocyte. However under aerobic conditions pyruvate continued to accumulate after all measurable oxygen capacity restoration (methemoglobin reduction) ceased. This is taken as evidence that in the presence of oxygen either methemoglobin formation continues in the treated cell, after all phenylhydrazine is destroyed or washed out, or that some other ferric iron compound is reduced which will not augment oxygen capacity. At the higher concentrations of phenylhydrazine used not all the oxygen capacity initially lost is restored on incubation even under anaerobic conditions. This inactive molecule is thought to be verdoglobin.
Inhibition of Glucose Utilization Following Thermal Injury: Uptake Studies by Diaphragm in Plasma From Burned Rats
Authors: Young M. Kendall , Seraile Leonard G. , Brown Wanda L.
Published: December 2017

Effect of thermal injury on tissue metabolism was studied by comparing the glucose metabolism of normal rat diaphragm tissue incubated in plasma from injured (plasma taken 15 min. after injury) and uninjured rats. Glucose concentrations in the plasma from the burned and control rats were made comparable to compensate for the hyperglycemia due to injury. An inhibition of glucose uptake by the diaphragm tissue incubated in plasma from burned rats was demonstrated, whereas the QO2 and the conversion of glucose-U-C14 to C14O2 were not significantly changed. This inhibition of glucose uptake was observed when dialyzed plasma from burned animals or the dialysate was used. Epinephrine under certain circumstances inhibited glucose uptake. These studies indicate that immediately after thermal injury, a disturbance in glucose utilization occurs; this disturbance appears to be other than in the conversion of glucose to CO2; a dialyzable principle is present in the plasma; and epinephrine is not excluded as a causative agent.
Effect of Insulin on Transport of Several Hexoses and Pentoses Into Cells of Muscle and Brain
Authors: Park C. R. , Johnson L. H. , Wright J. H. , Batsel H.
Published: December 2017

The effect of insulin on transport of d-glucose, d-mannose, d-fructose, d-xylose, l-arabinose and d-ribose through the cell membrane has been studied. Each sugar was infused into eviscerated rats with or without insulin for 1 or 2 hours. The accumulation of free sugar within the cell was determined in the diaphragm, heart, gastrocnemius and brain. Intracellular sugar was estimated by subtracting the amount of sugar in the extracellular fluid space, as determined with mannitol-1-C14, from the total tissue sugar. In muscle virtually no intracellular free sugar was detected in the absence of insulin whereas, in the presence of insulin, large amounts were found except in the case of d-ribose. Since these sugars do not arise by intracellular metabolism, it was concluded that insulin accelerated their transport through the cell membrane. These and other observations support the view that membrane transport in muscle is a site of insulin action. The transport process is distinct from phosphorylation and presumably involves combination of the sugar with a constituent of the cell membrane. In brain, no effect of insulin was observed. d-Mannitol, d-ribose and d-fructose did not pass the blood-brain barrier to a measurable extent. This explains the inefficacy of fructose in relieving the symptoms of hypoglycemia.
Cardiovascular Response to Hypothermia: Effect of Cold Acclimatization
Authors: Covino Benjamin G. , Beavers William R.
Published: December 2017

The cardiovascular response to hypothermia was studied in dogs which had been exposed continuously to sub-zero arctic temperatures for a period of 1–4 weeks. All dogs exposed in this fashion showed a significantly lower terminal rectal temperature than unexposed control dogs. In addition, the incidence of ventricular fibrillation was reduced in direct proportion to the exposure period. Acclimatization to cold appeared complete in dogs exposed for a period of 4 weeks. In this group of animals, the frequency of ventricular fibrillation was reduced to 9% as compared to an incidence of 96% in the control dogs. The process of acclimatization occurred with extreme rapidity. Dogs which were deemed fully acclimatized, became deacclimatized after 5 days in a warm environment. Both the frequency of ventricular fibrillation and the mean terminal rectal temperature of this group were the same as that in the control unexposed group.
Differences in Thyroid Activity of Several Strains of Mice and F1 Hybrids
Authors: Amin A. , Chai C. K. , Reineke E. P.
Published: December 2017

Thyroid secretion rate was determined in four strains of inbred mice and two groups of F1 hybrids. In all genotypes the thyroid secretion rate was consistently but not significantly greater in males than in females. The average thyroid secretion rates, expressed as micrograms l-thyroxine/ 100 gm body weight with the standard errors for the males and females, were: A/Jax 2.13 ± 0.12 and 1.84 ± 0.10; BALB/c 2.44 ± 0.21 and 1.84 ± 0.12; C57BR/cd 3.35 ± 0.34 and 2.45 ± 0.11; C57BL/6 4.19 ± 0.64 µg. and 3.33 ± 0.34. The secretion rate for hybrids CAF1 and BBF1 males and females, respectively, were: 2.34 ± 0.185 and 1.84 ± 0.106; 3.79 ± 0.644 and 2.74 ± 0.268 µg/100 gm. C57BL strain and BBF1 hybrid had significantly higher secretion rates than all other groups. The results are consistent with the output rate values reported earlier by the same authors, and clearly indicate that thyroid activity is under genetic control.
Drug Responses of Human Fetal Esophagus
Authors: Hughes F. Barbara
Published: December 2017

The drug-induced activity of human fetal esophageal preparations has been studied in vitro. The age of the fetuses was from 20 to 26 weeks. Both intact preparations and those of the separated muscularis mucosae have been used. All preparations responded similarly insofar as they contracted when either acetylcholine, pilocarpine, histamine, physostigmine or barium was added to the bath. Epinephrine inhibited spontaneous movement in both preparations and in addition relaxed intact preparations which had previously been stimulated with acetylcholine.
Effect of Long-Lasting Epinephrine on Serum Lipid Levels
Authors: Kaplan Alex , Jacques Stafford , Gant Mary
Published: December 2017

The injection of long-lasting epinephrine into dogs was followed in 1 hour by a rise in the concentration of serum triglycerides that was sustained for 24 hours. The concentrations of serum lipid phosphorus and cholesterol, however, were not perceptibly altered for the first 6 hours after the injection but were consistently elevated at the 24-hour period. Single injections of hydrocortisone, cortisone acetate or ACTH did not raise the serum concentration of lipid phosphorus or cholesterol in the 24-hour period after their injection. The triglyceride fraction did not rise significantly after cortisone or ACTH but did in some dogs receiving hydrocortisone.
Action of Adrenocorticotropin on Pregnancy and Litter Size in Rats
Authors: Velardo Joseph T.
Published: December 2017

Previously it was reported that adrenocorticotropin (ACTH) displayed the ability to restrict the action of estradiol-17ß in uterine growth and of progesterone in decidual development. This study concerns the influence of a highly purified and potent preparation of ACTH on pregnancy and litter size in albino rats of known reproductive vigor. Experimental procedures consisted of injecting ACTH prior to, immediately after mating and 11 days after mating. These data indicate that ACTH has the ability to reduce litter size and produce a large number of stillbirths. The most marked effects were observed when ACTH was injected on the day of mating and for 6 subsequent days. Normally, the litter size of nontreated controls is 9.6 ± 0.5. The daily injection of 2.0 and 4.0 mg ACTH daily for 7 days after mating effected reduced litters, 5.0 ± 1.7 and 3.9 ± 1.5, respectively. Furthermore, such treatment produced 27 stillborns on the 2.0-mg dosage and 39 on the 4.0-mg treatment. ACTH administered to adrenalectomized rats neither modified pregnancy nor litter size. ACTH given to intact rats effected a decrease in the fetal body weights. Such was not observed in the adrenalectomized groups nor in the ACTH-treated, adrenalectomized series. These data strongly indicate that the effects observed are mediated by way of the adrenal glands, and additional evidence is offered supporting the contention that there are numerous interactions among hormones of adrenal cortex and the ovaries.
Adrenal, Hypophyseal and Pancreatic Hormones in the Liver Glycogen Response to Low Atmospheric Pressure
Authors: Langley L. L. , Gunthorpe C. H.
Published: December 2017

The administration of 3 cc of adrenocortical extract (Upjohn) to adrenalectomized rats fasted at sea-level fails to cause liver glycogen deposition. Such animals under low atmospheric pressure accumulate about 1% liver glycogen. Adrenalectomized-hypophysectomized rats maintained on a minimal dose of hypophyseal extract, given 3 cc of adrenocortical extract and stressed do not deposit liver glycogen. These results suggest that the hypophyseal hormones function not only to control the adrenal cortices under these conditions, but also may contribute directly to the observed carbohydrate alterations. When larger doses of hypophyseal hormones are used there is a significant difference in liver glycogen between the stressed and nonstressed groups indicating the possible implication of still another agent, perhaps insulin, since alloxan diabetic rats do not accumulate liver glycogen in response to low atmospheric pressure.
Some Effects of Pentobarbital Anesthesia on Renal Hemodynamics, Water and Electrolyte Excretion in the Dog
Authors: Blake William D.
Published: December 2017

Studies were made on dogs to clarify the actions of pentobarbital anesthesia on renal function. The depression of renal function frequently observed when anesthesia is induced in animals hydrated with water or hypotonic saline solutions was confirmed. When the neurogenically and hormonally mediated components of the response to pentobarbital are respectively blocked by dihydrogenated ergot alkaloids and Pitressin infusion, pentobarbital anesthesia increases sodium excretion rather than decreasing it. Infusion of pentobarbital directly into the renal artery suggests that this natriuresis is caused by a toxic action of the anesthetic on the sodium reabsorptive process. Some inhibition of the glucose transport process has also been described.
Effect of Unilateral Carbon Dioxide Breathing on Pulmonary Blood Flow
Authors: Peters Richard M.
Published: December 2017

The effect of breathing increased concentrations of carbon dioxide was studied in dogs. Each lung was independently ventilated with the chest open. The pulmonary artery pressure was recorded and blood flow determined for each lung by the Fick principle during room air breathing. After this control period, increased concentrations of carbon dioxide were substituted for room air in one lung and the above determinations repeated. In all but 2 of 11 animals the pulmonary vascular resistance fell in the CO2 lung and the blood flow to this lung increased.