bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative bio-assay of secretin and pancreozymin in rats and dogs
Authors: Lin T. M. , Alphin R. S.
Published: December 2017

The dose-response relationship of secretin and volume flow and of pancreozymin and enzyme production was explored in the rat and dog. The relative sensitivity of the two species to the same secretin and pancreozymin preparations was compared. Anesthetics such as ether, chloroform, secobarbital, or pentobarbital sodium depressed the response of the rat to secretin. Linearity of response to secretin was observed in both rats and dogs; the range in the dog was 0.03– 0.5 mg/kg, whereas in the rat it was approximately 1.25–12.5 mg/kg. The threshold dose of secretin was the same for anesthetized and conscious rats, but the response of conscious rats to identical doses was much greater than that of anesthetized rats. A linear relationship between enzyme output and log dose of pancreozymin was found in both species; the dose range in the dog was from 2.5 to 1,000 µg, whereas in the rat the threshold dose was about 1 mg. Thus, the dog is more sensitive to both secretin and pancreozymin than the rat. Since results in the dog were easily reproducible, the dog is still the animal of choice for bio-assay of secretin and pancreozymin.
Umbilical venous pressure and other cardiovascular responses of fetal lambs to epinephrine
Authors: Reynolds S. R. M. , Mackie John D.
Published: December 2017

Large fetuses in utero are more sensitive to infused epinephrine than smaller ones. The quality of response is the same. Increased arterial blood pressure and heart rate are associated with an increase in umbilical vein pressure. The large fetus is as sensitive as the pregnant ewe and the latter is more sensitive than the nonpregnant ewe. Single injections of epinephrine into umbilical or femoral veins have similar effects, except for the difference that the latent period is about twice as long when epinephrine is given by the femoral route as by the umbilical route. The sphincter of the ductus venosus is believed to constrict in response to epinephrine. It is shown to be adrenergically controlled. The import of the sphincter for maintenance of umbilical vein pressure is considered.
Pressor responses to norepinephrine in humans before and after corticosteroids
Authors: Sambhi Mohinder P. , Weil Max H. , Udhoji Vasant N.
Published: December 2017

Pressor responses produced by intravenous injections of graded doses of norepinephrine were recorded in ten normal subjects before and after pharmacologic doses of glucocorticoids. Two subjects had been pretreated with 9α-fluorocortisol. Although a considerable variation was found in the responsiveness to repeated norepinephrine injections, variance analysis demonstrated that administration of adrenal cortical hormones and their analogues did not significantly alter the response. These observations do not support the hypothesis that acute administration of corticosteroids in large doses potentiates the pressor effects of catecholamines in the human subject with normal adrenal function.
Motoneuron resting potentials in spinal shock
Authors: Barnes Charles D. , Joynt Robert J. , Schottelius B. A.
Published: December 2017

The resting membrane potential of cells in the lumbar segment of the spinal cord was measured in cats before, during, and after the cord was functionally blocked. Blocking was achieved by cooling with o C brine passed through a copper tube surrounding the cord at the midthoracic level. Of those units identifiable by antidromic stimulation as motoneurons, 95% underwent a hyperpolarization of from 2 to 6 mv (mean 3.6 ± .2 mv) when the cord was blocked. A group of units that could not be identified as motoneurons underwent a hyperpolarization of from 2 to 8 mv (mean 3.7 ± .5 mv). The physiologic derangement in spinal shock is a hyperpolarization of motoneurons. Such hyperpolarization is thought to result from the removal of random synaptic bombardment by nerve endings, either directly or indirectly activated from more cephalad regions, which normally keep the cell in a slightly hypopolarized state.
Effect of potassium depletion on distribution of urea and thiourea-C14 in rat kidney
Authors: Bray George A.
Published: December 2017

Studies are presented on the effect of potassium depletion on the permeability of the collecting duct of the rat kidney to water and on the ability of the rat kidney to accumulate urea. The data show that the collecting duct of the potassium-depleted rat has essentially the same permeability characteristics for urea and thiourea-C14 as that of the normal rat. These data are discussed in relation to the effect of potassium depletion on the renal concentrating mechanism.
Effect of increased venous pressure on renal hemodynamics
Authors: Hinshaw Lerner B. , Brake Charles M. , Iampietro P. F. , Emerson Thomas E.
Published: December 2017

Evidence is conflicting regarding the effects of increased venous pressure on renal hemodynamics. Experiments to clarify its role were carried out on 28 intact, innervated or isolated, perfused dog kidneys. Findings indicate the absence of a "venous-arteriolar" reflex. Decreases in total resistance occur as venous pressure is increased through a wide range in both innervated and isolated perfused kidneys. Intrarenal venous and tissue pressures and blood flow are unaffected by large increases in venous pressure (21–75 mm Hg) although venous segment resistance declines markedly. Decreases in blood flow are seen when renal vein pressure approaches or exceeds intrarenal venous and tissue pressures. Results confirm previous investigations regarding the importance of tissue pressure and intrarenal venous pressure in renal hemodynamics, which appear to "buffer" the kidney against effects of elevated venous pressure through a variable but unusually large venous pressure range. The phenomenon of autoregulation may be extended to include a tendency for renal blood flow constancy in the face of wide swings in both renal artery and venous pressures.
Local effect of adenosine mono-, di-, and triphosphate vessel resistance
Authors: Frohlich Edward D.
Published: December 2017

The local effects of adenosine mono-, di-, and triphosphate (AMP, ADP, and ATP) on resistance to blood flow through large and small vessels of the forelimb were studied in 14 anesthetized dogs. This was accomplished by holding blood flow constant to the forelimb while pressures in the brachial artery, cephalic vein, and a small artery and vein in the forepaw were recorded. Acute local elevation of plasma AMP, ADP, and ATP concentration greatly decreased resistance to blood flow in the small vessels over a wide dose range. It is concluded that AMP, ADP, and ATP act primarily on small vessels, and particularly arterioles, to produce active vasodilatation.
Electroretinographic luminosity functions of the Aotus monkey
Authors: Jones Arthur E. , Jacobs Gerald H.
Published: December 2017

Electroretinographic studies were conducted on 19 Aotus monkeys. Seventeen of the animals were anesthetized with pentobarbital sodium, and two were quieted with Flaxedil and used unanesthetized. Studies of the response of the dark-adapted and light-adapted eye to flashes of light failed to reveal either a Purkinje shift or a photopic luminosity function. Studies on 12 animals using flicker techniques revealed a Purkinje shift in 9 animals and a typical photopic luminosity function in 6 animals. Three animals displayed no shift at all. In all cases, response magnitude by intensity curves were constructed and equal response curves determined. Equal response curves for brief flashes of light and 4-cycles/sec flicker closely parallel the ICI (International Commission on Illumination) scotopic function, and equal response curves for 12- and 20-cycles/sec flicker in six animals are in fair agreement with the ICI photopic function. Three animals produced bimodal curves with maxima at 510 and 590 µ.
Ventromedial hypothalamic lesions without hyperphagia
Authors: Reynolds Robert W.
Published: December 2017

Radio-frequency current and electrolysis were used to place ventromedial hypothalamic lesions in rats. In general, the two types of lesions differed in their effects on weight gain, water intake, and emotionality. In particular, radio-frequency destruction failed to produce the hypothalamic hyperphagia which follows electrolytic lesions. It is suggested that the symptoms of hyperphagia resulting from electrolytic lesions are irritant effects produced by electrochemical metallic deposition rather than the result of simple tissue elimination.
Response of the motor unit of the rat to paired stimuli
Authors: Locke Simeon
Published: December 2017

The response of the single motor unit of the gastrocnemius of the rat to paired stimuli delivered to a ventral root filament was studied. The peak-to-peak potential of the unit in response to the second of paired stimuli was 5–15% lower than the amplitude of a single response, and persisted in many cases at a stimulus interval greater than 30 msec. The absolute refractory period ranged from 0.6 to 2.3 msec. The absolute irresponsive period ranged from 1.1 to 2.75 msec. With decreasing stimulus intervals, the second response declined in peak-to-peak amplitude, increased in duration, and developed multiple peaks with variable latency. It is suggested that variability of response characteristics of subunits, the anatomic nature of which is unknown, allows the motor unit to be fractionated under certain experimental conditions.
Reflex antidiuresis after occlusion of common carotid arteries in hydrated dogs
Authors: Perlmutt Joseph H.
Published: December 2017

Common carotid arteries were occluded bilaterally for 5 min below the thyrocarotid arterial junctions in mildly hydrated, anesthetized dogs. Within 5–15 min after the occlusion, urine flow declined and remained below control values for 30–105 min. Concurrently, the urine became hypertonic to systemic plasma and there was no evidence for renal vasoconstriction or increased solute reabsorption. The decrement in urine flow was accounted for entirely by the decline in free-water clearance. Prolonged periods of occlusion or increased hydration altered the response. Bilateral occlusion of the common carotid arteries for 5 min above intact thyrocarotid arterial junctions (but below the carotid sinuses) or below denervated thyrocarotid arterial junctions did not affect urine flow. The time course of the response, the characteristics of the urine, and the absence of renal vasoconstriction suggest that the procedure induced a reflex release of antidiuretic hormone. Furthermore, the data indicate that the receptor area for this reflex is located in the region of the junction of the common carotid and thyroid arteries.
Local vascular effects of hypokalemia, alkalosis, hypercalcemia, and hypomagnesemia
Authors: Haddy Francis J. , Scott Jerry B. , Florio Michael A. , Daugherty Robert M. , Huizenga Judith N.
Published: December 2017

Blood flowing through the vascular beds of the dog forelimb, kidney, and heart was transiently rendered hypokalemic (1.9 meq/ liter), alkalotic (pH 7.54), hypercalcemic (6.4 to 13.5 meq/ liter), hypomagnesemic (1.2 meq/liter), and hypocalcemic (3.0 meq/liter), singly and in various combinations, while observing resistance to flow and heart contractility. This was accomplished by holding flow rate constant while measuring the effects of rapid intra-arterial infusion of various artificial solutions upon perfusion pressure and left ventricular contractile force. The new findings are a) in situ limb small vessels and kidney vessels respond to local hypokalemia with slight constriction; b) in situ limb small vessels and kidney vessels respond to combinations of local hypokalemia, hypercalcemia, alkalosis, and hypomagnesemia with much more marked constriction than occurs with any one of the abnormalities alone; c) intact heart responds to local hypercalcemia with increased contractile force, to alkalosis with increased coronary resistance, and to combinations of hypokalemia, hypercalcemia, alkalosis, and hypomagnesemia with increased contractile force and increased coronary resistance; and d) in situ limb small vessels and intact heart respond to local hypocalcemia with dilation and decreased contractile force, respectively.
Effect of aldosterone administration on electrolyte excretion and GFR in the rat
Authors: Finn Arthur L. , Welt Louis G.
Published: December 2017

Two groups of rats were fed equal quantities of an electrolyte-free diet which was supplemented with potassium by gavage. One group received aldosterone in sesame oil and the other the vehicle by daily injection. The excretion of potassium was not influenced by the administration of aldosterone. In addition, there was no effect on the filtration rate or tissue electrolyte composition.
Synthesis of alpha- and beta-globulins in normal and liverless dog
Authors: Kukral John C. , Sporn Joseph , Louch June , Winzler Richard J.
Published: December 2017

Incorporation of dl-S35 methionine into electrophoretically separated α1-, α2-, and ß-globulins was studied in the same four dogs before and after total hepatectomy. In the normal animal methionine was incorporated rapidly into both α- and ß-globulins. Peak specific activity was attained in all fractions at approximately 6–12 hr. The α1- and α2-globulins had approximately equal specific activity, expressed as counts per minute per milligram of each fraction, whereas the activity of ß-globulins was about one-half that of either α-globulins. Hepatectomy markedly reduced the formation of labeled α1- and α2-globulins to only 10% and 25% of the prehepatectomy levels, respectively. Incorporation of methionine into the ß-globulins was not reduced so extensively by hepatectomy, falling only to one-half of normal levels. These observations lead to the conclusion that most (75–90%) of the α-globulins are produced by the liver but that only about 50% of the ß-globulins are of hepatic origin.
Effect of growth hormone and thyroxin on cardiovascular system of hypophysectomized rats
Authors: Beznak Margaret
Published: December 2017

Growth hormone, thyroxin, or growth hormone and thyroxin were given for a period of 4 weeks to rats hypophysectomized 2–3 months previously. The effect of these treatments on blood pressure, weight and rate of the heart, cardiac output, and work was measured under basal conditions and during acute loading (infusion of polyvinylpyrrolidone into the right side of the heart) as well as during chronic loading (constriction of the aorta). The changes in cardiovascular parameters in the basal state due to hypophysectomy could all be reversed by thyroxin treatment. Thyroxin alone was inadequate in restoring the response of the hearts to either acute or chronic loading. Growth hormone in combination with thyroxin could restore or even exaggerate the normal response to both chronic and acute loading as well as maintain the basal parameters. Growth hormone itself had comparatively little effect; it caused some increase in the weight of the heart and stroke volume. It is concluded that both thyroxin and growth hormone are necessary for the normal function of the cardiovascular system.
Effect of thoracic duct to esophagus shunt in dogs with vena caval constriction
Authors: Dumont Allan E. , Mulholland John H.
Published: December 2017

Ascites developed promptly in four dogs in which the supradiaphragmatic vena cava was constricted. In another six dogs undergoing the same operation, the thoracic duct was drained by cannula into the esophageal lumen; ascites did not occur. Ascitic fluid forms following constriction of the inferior vena cava by leakage of excess liver lymph into the peritoneal cavity. Capacity of the thoracic duct to transport an increased quantity of lymph is limited by resistance to flow at the veno-lymphatic junction in the neck. This study demonstrates that ascites does not occur when resistance to excess thoracic duct lymph flow is removed by permitting free flow of lymph into the esophagus.
Effect of low concentrations of cyanide on QOO2 of tissue slices
Authors: F. Adolfo Fernandez , Gonzalez-Quintana Jorge , Russek Mauricio
Published: December 2017

The oxygen consumption of brain, liver, and kidney slices measured in the Warburg apparatus was not significantly depressed by concentrations of sodium cyanide of 0.2, 0.5, and 2 µg/ml. This last concentration is considered equal to that attained in the blood after an injection of 0.2 mg/kg, which produces remarkable in vivo effects described elsewhere. Therefore, the effects obtained in vivo cannot be due to the depression of tissue respiration by cyanide, but are probably caused by the stimulation of chemoreceptors. A concentration of 5 µg/ml notably reduced the QOO2 of brain slices, and 10 µg/ml reduced that of all three tissues. As reported by others, 50 µg/ml reduced the QOO2 of kidney slices by 80%. It is noteworthy that 0.2 µg/ml of NaCN produced a 40% increase ( P < 0.01) in the QOO2 of liver slices but only a 5–13% increase, not statistically significant, in brain slices.
Energy metabolism of dogs after total destruction of the central nervous system
Authors: Galvão Paulo Enéas , Tarasantchi Jacob , De Magalhães Carlos Alberto E.
Published: December 2017

The central nervous system of male adult dogs was destroyed by an injection in the cisterna magna, of a 20% NaCl solution, under 60 cm Hg pressure, during 6 min (technique of Galvão and Pereira). One hundred and sixteen O2 consumption determinations were made by analysis of the expired air or of the air pumped through the lungs, in 28 dogs, before and after CNS destruction. The metabolism level was generally well maintained during the first hours after the destruction and was materially unaltered in some dogs until death. However, in many dogs the heat production decreased more or less gradually in the later hours, and attained a mean lowering of 16.8%. The anesthesia employed, the abolition of muscle tonus and work of respiratory muscles, the respiration of the CNS, and the loss of a trophic or metabolic action of the CNS are discussed in an attempt to explain the metabolic rate of animals deprived of CNS.
Single proximal tubules of Necturus kidney. VII: Ion fluxes across individual faces of cell
Authors: Solomon A. K.
Published: December 2017

A method has been devised to calculate the fluxes across the individual faces of Necturus kidney proximal tubule cells. For this purpose data obtained from experiments using the stopped-flow microperfusion technique of measuring tracer disappearance from the tubular lumen are combined with data obtained in earlier experiments in which tracer uptake in Necturus kidney was measured. The combined data have been analyzed on an analogue computer on the assumption that the system may be described with three compartment kinetics (compartment 1, lumen; 2, proximal tubular cells; 3, extratubular space). For Na, the flux from compartment 1 to 2, φ'12, = 308 pmoles/cm2 sec, and the remaining fluxes in the same units are: φ'21, 246; φ'23, 132; φ'32, 89. In the case of K, the fluxes are φ'12 = φ'21 = 57; φ'23 = φ'32 = 378. It has not been possible to obtain an analogue computer solution for the Cl fluxes in all cases. The interpretation of these calculated Na and K fluxes is discussed both in terms of the assumptions involved in the calculations, and in the application of the Ussing flux ratio for ion transport.
Effect of rate changes on strength and time course of contraction of papillary muscle
Authors: Koch-Weser Jan
Published: December 2017

The influence of 14 frequencies of contraction (between 0.2 and 300 beats/min) on the development of tension and on the time course of contraction was determined in 40 isometrically contracting, isolated cat papillary muscles at 38 C. Only cylindrical muscles with radius <0.43 mm were included, since this was found to be the maximum thickness compatible with normal development of tension at high frequencies. Increases in frequency were associated over the entire range with decreases in the time to peak tension (total 40%) and in the relaxation time (total 49%), and increases in the maximum rate of development of tension (total 560%) and in the peak tension developed (total 340%). These findings indicate that changes in heart rate alter both the degree of activation of the contractile elements and the duration of their active state. It is concluded that the opposing effect of both of these changes must be considered in any analysis of the influence of alterations in rate or rhythm of the heart on the strength of contraction of mammalian ventricular muscle.
Potassium efflux of squid giant axons in low external divalent cation
Authors: Lipicky Raymond J. , Bryant S. H.
Published: December 2017

In squid ( Loligo pealii) giant axons, potassium efflux was measured after soak-loading during washout, and membrane potentials were monitored using an intracellular pipette electrode. As external divalent cation is lowered down to 1/10 of normal, there is little change of resting potassium efflux or resting membrane potential (slight hyperpolarization), despite a tendency of the axon to fire repetitively. Below this concentration, efflux rises as much as eight times the normal 265 pmole·cm–2·sec–1 and potential falls (from 55 as far as 32 mv), inexcitability occurring at about 1/100 of normal external divalent cation concentration.
Influence of nonionic diffusion on absorption of NH4+ and HCO3– from the bladder
Authors: Rosenfeld Joseph B. , Aboulafia Elie D. , Schwartz William B.
Published: December 2017

Studies have been carried out to compare the losses of NH4+ and of HCO3– from the dog bladder in vivo when: 1) each of these ions was present separately as the salt of a strong electrolyte, and 2) both ions were present together as ammonium bicarbonate. The initial concentration of electrolyte in each experiment was 100 mmoles/liter. After instillation of ammonium chloride (pH 8), [NH4+] fell by a mean of 20 mEq/liter in 8 hr, whereas after instillation of ammonium bicarbonate, [NH4+] fell by a mean of 67 mEq/liter ( P < .001). After instillation of sodium bicarbonate, [HCO3–] fell by only 10 mEq/liter, whereas in the ammonium bicarbonate experiments it fell by 58 mEq/liter ( P < .001). It is proposed that the larger loss of NH4+ and HCO3– which occurred in the ammonium bicarbonate experiments resulted from the simultaneous and rapid diffusion of NH3 and CO2 with continuous regeneration of each nonionic species at the expense of the ionic member of each buffer pair. These observations suggest that nonionic diffusion, under some conditions, may lead to significant transfers of weak electrolytes across the bladder wall.
Precordial recording of albumin-I131 in estimation of cardiac output in the rabbit
Authors: Grünert Rolf D. , Oeff K. , Schmidt H.
Published: December 2017

Precordial isotope dilution curves in the rabbit were employed to calculate cardiac output. I131-labeled human serum albumin was used as an indicator. Satisfactory correlation was found between cardiac output determined by this method and simultaneous evaluation of arterial dilution curves. In normal rabbits lightly anesthetized with ether, the cardiac output as measured by precordial recording was 141.4 ± 31.5 ml/kg in rabbits weighing between 2.1 and 3.75 kg, which corresponds well with data obtained by the Fick and dye-dilution methods obtained by previous workers.
Distribution of labeled erythrocytes in adipose tissue and muscle in the rat
Authors: Hausberger Franz X. , Widelitz Martin M.
Published: December 2017

Distribution of erythrocytes with chromium 51 was used to compare the capillary volume of adipose tissue and resting skeletal muscle of rats. Based on wet weight, the vascular bed of adipose tissue is of the same order of magnitude as that of muscle, whereas the protein content of the muscle is approximately 16 times greater. The size of the vascular bed per gram of adipose and muscle tissues decreased considerably during aging.
Seasonal changes in glucose tolerance and glycogen disposition in a lizard
Authors: Maggio Anthony Di , Dessauer Herbert C.
Published: December 2017

Forty milligrams of glucose in 0.4 ml of water were injected intraperitoneally into fasted adult male lizards, Anolis carolinensis, in different seasons. At intervals of 3 hr to 5 days following injection lizards were sacrificed and their tissues analyzed for carbohydrate. Blood glucose returned to fasting level in less than 36 hr in spring and summer but remained above fasting level for over 2 days during autumn and winter. Generally, 4–6 g of glycogen were deposited per 100 g of liver per day. Greater quantities of glycogen were deposited in liver during autumn than in other seasons. The rate of decrease of liver glycogen was slowest in autumn and winter. Extrahepatic glycogen did not increase after glucose injection in early summer and autumn but rose significantly in winter and spring. The decreased "glucose tolerance" of Anolis and its increased capacity to store glycogen in autumn and winter may be due to a decreased rate of carbohydrate oxidation in these seasons.
Fasting gastric content of the squirrel monkey (Saimiri sciurea)
Authors: Brodie D. A. , Marshall R. W.
Published: December 2017

Free acid was found in the fasting gastric contents of each of 13 squirrel monkeys studied. A comparison of gastric contents from unrestrained and restrained monkeys indicated that restraint significantly increased the free acid concentration. Over a 24-hr period, there was a decrease in volume, free acid and total acid concentration, and pepsin value of the gastric juice. Histamine (0.1 mg/kg hr, subcutaneously) produced a significant increase in free acid and total acid concentration, while the volume and pepsin values were not changed. Methacholine, at cumulative doses of 1.0 and 2.0 mg/kg, subcutaneously, produced a significant decrease in free and total acid concentration while the volume was not altered. Atropine, in cumulative doses of 8, 16, and 48 mg/kg, intraperitoneally, produced a significant fall in volume of gastric juice collected. However, free acid concentration was reduced only at the highest dose and total acid concentration was not changed by any of the doses tested.
Source of plasma free fatty acids in dogs receiving fat emulsion and heparin
Authors: Meng H. C. , Edgren B.
Published: December 2017

Unanesthetized dogs were given either 3.0 g fat/kg as a 20% fat emulsion or heparin (2 mg/kg) intravenously or both. Plasma free fatty acids (FFA) and lipolytic activity were determined at intervals. In some experiments hexamethonium (5 mg/kg), a sympathetic ganglionic blocking agent, was administered intravenously either before or after fat or heparin. In fasting dogs fat infusion produced a moderate and heparin caused a slight rise in plasma FFA. Heparin given during lipemia produced a marked elevation of plasma FFA. The plasma lipolytic activity was increased after fat emulsion or heparin. Hexamethonium reduced the fasting plasma FFA about 70% or 0.40–0.6 mEq/liter. A similar reduction of plasma FFA also was observed when hexamethonium was administered during fat infusion or after heparin. Hexamethonium did not affect the increase in plasma lipolytic activity following the administration of fat emulsion or heparin. It seems probable that the increase in plasma FFA observed after intravenous infusion of fat emulsion or heparin is mainly due to the result of intravascular lipolysis.
Secretion of corticosterone in rats with anterior hypothalamic lesions
Authors: Porter John C.
Published: December 2017

Secretory rates of corticosterone were determined in rats with intact hypothalami, in animals with anterior hypothalamic lesions, and in hypophysectomized rats with anterior hypothalamic lesions. Animals with intact hypothalami secreted 10.7, 13.2, 14.2, 14.7, 16.6, 17.5, 17.8, and 17.7 µg corticosterone in the first through the eighth 15-min interval, respectively, of a 2-hr collection period. Rats with hypothalamic lesions secreted 1.8, 2.7, 3.6, 6.1, 9.0, 10.7, 11.1, and 10.6 µg corticosterone in the first through the eighth 15-min interval, respectively. Intravenous injection of 100 mU arginine vasopressin every 30 min did not affect the rate of production of steroid in animals with lesions. Removal of the pituitary from rats with hypothalamic lesions reduced the secretion to 0.3 µg corticosterone in 15 min. Administration of 5 mU ACTH at half-hour intervals to animals with lesions greatly increased the rate of production of corticosterone, suggesting that the low rate during the first 15-min collection period was not due to an unresponsive adrenal. The magnitude of the response of the acutely hypophysectomized rats to ACTH was slightly less than that of animals with lesions.
Reticuloendothelial depression with superior mesenteric artery occlusion
Authors: Blattberg Benjamin , Levy Matthew N.
Published: December 2017

Normotensive, splenectomized dogs were subjected to intestinal ischemia by occlusion of the superior mesenteric artery (SMA) for periods of 15–90 min. Autoperfusion of the liver with arterial blood at normal flow rates was maintained in order to prevent hepatic ischemia during the period of SMA occlusion. The phagocytic activity of the hepatic reticuloendothelial system was assessed by measuring the clearance of carbon particles. Intestinal ischemia for 30 min led to a significant ( P < 0.01) depression of carbon clearance. However, increasing the duration of ischemia to as long as 90 min did not produce a significantly greater depression of the clearance rate. Portal venous flow measurements, made just prior to the time of carbon injections, demonstrated that reduced phagocytic activity could not be attributed to reduced hepatic blood flow. Since ischemia of the hepatic RES was prevented during the period of SMA occlusion, it is probable that a humoral reticuloendothelial substance was produced by the ischemic intestine, as previously demonstrated in dogs subjected to hemorrhagic hypotension. In dogs treated with antibiotics to eliminate the gram-negative fecal flora, occlusion of the SMA for 1 hr caused depression of granulopectic activity. This suggests that gram-negative bacterial products are not required for the formation of the reticuloendothelial depressing substance.
Effects of ligation of uterine veins in pregnant rats
Authors: Lichton I. J.
Published: December 2017

Uterine veins were ligated on day 14 of gestation in 24 rats; this procedure ensures drainage of uterine blood via the ovarian veins only. Eighteen sham-operated rats served as controls. The uterine vein-ligated rats showed no tendency to accumulate excessive extracellular fluid during gestation, and they excreted more water and solute in response to isotonic saline loading at term than did the controls. These results afford no evidence to strengthen the hypothesis that high implantation with consequent uterine venous drainage predominantly through the ovarian veins is a cause of human pre-eclampsia-eclampsia.
Specific impedance of rabbit's cortical tissue
Authors: Harreveld A. Van , Murphy T. , Nobel K. W.
Published: December 2017

The impedance of a tissue slab consisting of both cortical gray and underlying white matter was measured at 1,000 cycles/sec between a surface electrode and a deep electrode placed in the lateral ventricle or in the underlying tissue. By calibrating the electrode assembly with a KCl solution of known conductivity the mean specific impedance of the slab could be computed. Through a hole in the center of the surface electrode a probe was lowered stepwise, and the potential between its tip and the deep electrode was determined after each change in position. In a graph of the potential plotted against the position of the tip, the ratios of the specific impedances of the various layers of tissues in the slab and the thicknesses of these layers could be determined. From these data and the mean specific impedance of the tissue slab the specific impedance of the cortex was computed. The mean value determined in 14 experiments was 208 ± 6 ohms cm. The specific impedance of the white matter was materially greater. Taking into consideration the conductivity of the blood in the vessels the specific impedance of the cortical tissue proper was estimated as 220 ohms cm.
Control of glycogen utilization and glucose uptake in the anaerobic turtle heart
Authors: Reeves Robert B.
Published: December 2017

Glucose uptake and lactate production of isolated, perfused turtle ( Pseudemys scripta) hearts were measured under anaerobic conditions. At low pressure-volume workloads the hearts used glycogen stores rather than exogenous glucose to provide hexose substrate for glycolysis. Glycogenolysis increased in proportion to increased workload up to a critical maximum value for each heart. Increase of workload beyond this critical point was associated with utilization of exogenous glucose or, in the absence of glucose, with mechanical failure of the heart. Glucose-U-C14 was quantitatively (98%) converted into lactate, and neither dilution of exogenous glucose specific activity nor incorporation of label into glycogen or fatty acids occurred. The maximal rate of glycogenolysis was found to be a linear function of initial glycogen concentration. It is concluded that the input of hexose units into glycolysis is regulated jointly by hexokinase and phosphorylase; however, the known properties of these two enzymes will not fully account for all the features of this regulation.
Anterior ciliary venous blood flow and oxygen saturation at reduced arterial pressure
Authors: Cohan Bruce E. , Cohan Sandra B.
Published: December 2017

Flow and oxygen saturation of blood in the anterior ciliary vein of the dog eye were measured as arterial pressure was reduced. Blood flow showed a proportional reduction with reduction in arterial pressure. In this respect this vascular bed behaves, in general, as a rigid tube system over the range of arterial pressures examined. The normally high oxygen saturation of anterior ciliary venous blood was remarkably constant as arterial pressure was reduced. The calculated value for oxygen consumption by the tissue drained by the anterior ciliary vein was, therefore, proportional to blood flow throughout the range of arterial pressures examined and, in this respect, this tissue behaves as a flow-limited organ.
Osmolality, bicarbonate concentration, and water reabsorption in proximal tubule of the dog nephron
Authors: Clapp James R. , Watson John F. , Berliner Robert W.
Published: December 2017

Micropuncture and microanalytical techniques were used to study the effect of antidiuresis and water diuresis on osmolality, bicarbonate concentration, and water reabsorption in the proximal tubule of the dog nephron. Samples collected during antidiuresis and water diuresis remained isotonic to plasma throughout the first 50% of the proximal convoluted tubule. Mean bicarbonate concentrations of 16 mEq/liter and 17 mEq/liter were found in the middle third of the tubule during antidiuresis and water diuresis, respectively. These values were slightly less than the plasma concentration of 22 mEq/liter. Proximal tubular fluid samples for inulin concentration were collected during antidiuresis, water diuresis, and during vasopressin infusion in water-loaded dogs. A mean tubular fluid to plasma (TF/P) inulin ratio of 2.3 was found in the middle third of the proximal tubule during antidiuresis. This value is significantly different ( P < 0.01) from a mean of 1.6 in the same portion of the tubule during water diuresis. Vasopressin administration to hydrated dogs returned the TF/P inulin ratio in the middle third of the proximal tubule to 2.0. These results suggest that vasopressin stimulated Na reabsorption in the proximal tubule of the dog nephron.
Influence of extracellular potassium levels on atrioventricular transmission
Authors: de Carvalho Antonio Paes , Langan William B.
Published: December 2017

Dependence of transmission of excitation along atrial and A-V pathways on extracellular K+ was studied in the isolated, Langendorff perfused, rabbit heart. It was found that atrial propagation velocity reaches a maximum at [K]0 = 6 mm; slowing, presumably due to depolarization, ensues at higher [K]0. Propagation between upper His bundle and ventricles seems to behave in a similar way. Transmission across the A-V nodal area is markedly impaired at [K]0 below 2 mm; A-V block is often observed. Higher [K]0 levels shorten the A-V nodal transmission time; this speeding of transmission persists in [K]0 levels high enough to cause impairment of propagation in atria. Furthermore, A-V nodal block caused by acetylcholine was shown to be abolished when [K]0 is raised to an appropriate level. This antagonistic action is probably not due to release of catecholamines by the increased [K]0. A possible explanation for the [K]0 dependence of A-V transmission is discussed in terms of the ionic hypothesis
Induced changes in the small vessel volume as determined by rheological relationships
Authors: Chacalos Elias H.
Published: December 2017

The cell and plasma volumes were determined simultaneously in dogs by means of P32-tagged erythrocytes and albumin-I131. With these measurements the excess plasma changes, after the administration of splenic blood or plasma and other small vessel active agents, were ascertained. In splenectomized dogs small vessel dilators such as splenic blood or plasma, potassium, and serotonin increased the excess plasma, while small vessel constrictors such as vasopressin and calcium reduced it. Mathematical analysis utilizing empirically vindicated rheological equations led to the derivation of equations that allowed, in splenectomized dogs, the calculation of the mean composite radius of all small vessels with a radius <0.150 mm, the composite small vessel hematocrit of the blood in these vessels, and the small vessel volume. The fractional distribution of cell and plasma volumes among the small and large vessel compartments could also be calculated. Calculations based on these equations demonstrated, among other results, that small vessel constrictors decreased the mean composite radius of small vessels and the small vessel volume, while small vessel dilators increased the values of these parameters.
Effect of exercise on FFA metabolism of pancreatectomized dogs
Authors: Issekutz B. , Miller H. I. , Rodahl K.
Published: December 2017

Normal and pancreatectomized dogs with indwelling arterial and venous catheters were exercised on the treadmill for 35 min. Palmitate-1-C14 was infused intravenously for 3 hr during the experiment, or administered orally 15 hr before the experiment. The plasma free fatty acid (FFA) level was decreased in normal dogs but increased in the pancreatectomized animals during exercise. This was due to corresponding changes in the rate of FFA release. The rate of uptake of plasma FFA followed the rate of release with some delay, so that at the end of exercise the uptake was tenfold higher in the pancreatectomized dogs than in the controls. In spite of this striking difference, the C14O2 output was increased during exercise four- to fivefold in both groups in the infusion experiments. When the radiopalmitate was administered orally, however, the specific activity of the exhaled C14O2 rapidly decreased in the exercising pancreatectomized dogs but remained rather constant in the controls. It is suggested that during heavy exercise the muscles of the normal dog oxidize their endogenous fat pools, whereas the pancreatectomized animal relies for fat oxidation on the plasma FFA, the concentration of which is considerably increased by norepinephrine in the absence of insulin.
Efflux of sodium from isolated toad bladder
Authors: Frazier Howard S. , Hammer Earle I.
Published: December 2017

A method of simultaneously determining the rates of loss of Na24 across the mucosal and serosal surfaces of the isolated toad bladder is described. The addition of vasopressin to the serosal medium causes an abrupt increase in the efflux of Na24 across the mucosal boundary, with no significant change in the efflux across the serosal surface. Replacement of sodium in the mucosal medium with choline causes no change in the efflux of Na24 across either the mucosal or serosal surfaces. The results indicate that the stimulation of active transport of sodium across the bladder after vasopressin is the result solely of an increase in the permeability to sodium of the mucosal surface. Vasopressin does not act directly on the active transport step at the serosal surface. In addition, the saturation kinetics which describe the process of sodium entry at the mucosal boundary are not the result of an exchange diffusion process, and appear not to be due to a sodium-induced change in the permeability of this surface to sodium.
Behavioral thermoregulation during vitamin B6 deficiency
Authors: Yeh Samuel D. J. , Weiss Bernard
Published: December 2017

Thermoregulatory behavior was studied in vitamin B6-deficient and control rats exposed to a temperature of 2–3 C. The animals were kept in an experimental chamber provided with a lever which, when pressed, turned on a heat lamp placed above the chamber. The B6-deficient rats turned on the heat lamp more frequently than did the controls. This difference was observed with both ad libitum and paired feeding. Furthermore, administration of vitamin B6 to the deficient rats and deoxypyridoxine, a B6 antagonist, to the controls brought about reversals in the relative frequency of heat reinforcements which were accompanied by changes in biochemical indices of vitamin B6 deficiency, i.e., increased xanthurenic acid excretion and decreased plasma glutamic-oxalacetic transaminase levels. Measurements of skin and rectal temperatures in the cold indicate that the body temperature of B6-deficient rats falls more rapidly than that of controls, a fact which would account for the difference in thermoregulatory behavior. Attempts to search for evidence of thyroid dysfunction in B6-deficient rats as the possible cause of such behavioral differences were unrevealing. These experiments indicate that behavioral studies are useful in assessing nutritional deficiency.
Effects of hypertonic solutions on bile formation
Authors: Chenderovitch J. , Phocas E. , Rautureau M.
Published: December 2017

Modifications of flow and composition of bile have been studied in the guinea pig with ligated ureters after injection of hypertonic solutions of two nonmetabolizable substances, mannitol and xylose (1.66 m), into the jugular vein. A distinct and persistent decrease in biliary flow always occurs. Analysis of this anticholeresis showed a parallel decrease in the flow of water and electrolytes, while the flow of bilirubin and bile acids is not modified. There are, then, two different types of mechanisms in the formation of bile: the osmotic mechanisms which control the quantity of water and electrolytes; and the active secretory mechanisms, independent of the first, for specific substances such as bilirubin and bile salts. Ultrafiltration does not occur in quantitative formation of bile, but the bile/blood osmotic gradient plays an important role.
Persistent dynamic phase of aurothioglucose obesity
Authors: Friedman Gerald , Waye Jerome D. , Janowitz Henry D.
Published: December 2017

Continuous long-term observations on food intake, body weight, and the development of obesity were made on the survivors of an ld50 dose of aurothioglucose (ATG). ATG-obese mice consumed significantly greater amounts of food compared to ATG-nonobese and control animals from the 2nd to the 13th months of observation. The daily food consumption of obese animals remained relatively constant from the inception of hyperphagia to senescence. Food intake in the two control groups remained constant throughout 18 months of observation. Throughout the latter time period the obese animals had significantly greater weights than their ATG-nonobese and control littermates. No significant differences in weights were noted between ATG-nonobese mice and controls during the total period of observation. Obese mice progressively gained weight until the 12th month, after which a gradual decline was observed. At no time was a weight plateau evident. It is concluded that the long-term progressive weight gain in ATG-obese mice is consistent with a persistent dynamic phase of obesity until senescence.
Adrenocorticotropic activity in the rat assessed by in vivo and in vitro indices
Authors: Van Goch J. J. , Wied D. De , Schönbaum E.
Published: December 2017

Several indices of adrenocorticotropic (ACTH) activity were compared in order to establish the index most suitable for assay purposes, particularly of ACTH in blood. In hypophysectomized rats, the effects of ACTH on adrenal ascorbic acid, cholesterol, and steroid formation in vitro were studied. In intact rats, the effects of formalin on these variables as well as on the adrenal and plasma corticosterone levels and hypophyseal and blood ACTH activity were measured. Adrenal corticosterone as well as steroid formation in vitro increased very rapidly after stimulation by ACTH. In hypophysectomized rats, after intravenous ACTH, significant increases were observed after 5 min. In normal rats, 3 min after the injection of formalin, significant increases of steroid formation in vitro and ACTH activity were observed. The in vitro technique is suitable for the study of changes in ACTH activity. ACTH increases the fraction of corticosterone found in the total amount of corticoid secreted by rat adrenals in vitro.
Time course of fecal steroid-C14 excretion in various rodents
Authors: Beher W. T. , Baker G. D. , Penney D. G.
Published: December 2017

A study was made of the rates of fecal excretion of sterol-C14 and bile acid-C14 during a 7-day period after an intraperitoneal injection of dl-mevalonic acid-2-C14. The percentages of fecal C14 steroids excreted as bile acid-C14 by several species were: mouse, 51%; hamster, 62%; rat, 62%; guinea pig, 33%; gerbil, 66%; and rabbit, 56%. The balance of excretion was neutral sterol-C14. The ratios of fecal bile acid-C14 to neutral sterol-C14 varied with time. The animals can be divided into three groups in respect to rate of excretion: rat and mouse had high excretion rates; gerbil an intermediate rate; while hamster, guinea pig, and rabbit had low rates. The amounts of C14 sterols retained in serum, liver, and carcass after 7 days were determined. The highest retained activity was in guinea pig and rabbit, the lowest in rat tissues. The sum of excreted steroid-C14 and retained sterol-C14, which equals total synthesized steroid-C14, was calculated. Guinea pig, rat, and mouse incorporated the greatest amount of C14; gerbil, an intermediate amount; and hamster, the smallest amount.
Adaptations to diving in the harbor seal— gas exchange and ventilatory response to CO2
Authors: Robin Eugene D. , Murdaugh H. Victor , Pyron William , Weiss Edgar , Soteres Peter
Published: December 2017

Pulmonary gas exchange and the ventilatory response to CO2 were measured in six female harbor seals, Phoca vitulina. Mean Paco2 (48 ± 6 mm Hg) is higher in the seal and mean Pao2 (88 ± 9 mm Hg) is lower than the corresponding value in man. The seal shows a depressed ventilatory response to CO2 both in terms of slope and intercept of CO2 response curves. The depressed respiratory center sensitivity to CO2 presumably is an adaptative mechanism permitting prolonged diving in this species.