bluuebunny/crossref_metadata_2025 huggingface dataset:
Blood supply and distribution of albumin and red cells in rabbit kidney
Authors: Serratto Maria , Flanagan C. Larkin , Earle David P.
Published: December 2017

Intravenously administered I131 albumin (RISA) is more concentrated in medulla than in cortex of the normal rabbit kidney. In contrast, labeled erythrocytes are more concentrated in normal rabbit renal cortex than in medulla. Collateral circulation to rabbit renal parenchyma arises from capsular and ureteral arteries. The magnitudes of these two blood supplies are small and roughly equal. Both cortex and medulla receive blood from both groups of collaterals. When capsular vessels alone supply the kidney, renal weight and concentrations of RISA and labeled erythrocytes increase progressively with time up to 1 hr. This suggests a preponderance of arterial over venous and lymphatic collaterals after acute renal pedicle occlusion. RISA concentration of the contralateral medulla of the rabbit whose left renal artery and vein have been occluded increases rapidly and remains high for 1 hr as compared to control animals.
Utilization of massive doses of amino acids in protein and porphyrin biosynthesis
Authors: Walter Harry , Zipper Herbert , Biermann Ludwig
Published: December 2017

Rats were injected intravenously with doses up to 250 mg of glycine containing a tracer quantity of glycine-2-C14. Between 1 and 15 days the animals were exsanguinated and globin, hemin, and plasma proteins isolated and counted. The relative specific activity (i.e., counts per minute per 100 mg sample/counts per minute injected per gram body wt.) found in globin, hemin, and plasma proteins was only slightly affected by the size of the administered dose of glycine. Thus, typically, the relative specific activity of the globin of rats injected with 0.015 mg was only two to three times greater than that in rats injected with 250 mg; for the hemin this difference was somewhat larger but still less than fourfold. Determination of relative specific activity values for globin and plasma proteins when small or large doses of methionine were injected, yielded results similar to those found with glycine. The total per cent of excretion, in the urine and in the expired air, of the radioactivity administered with the different doses of glycine, was also found to be quite similar. This indicates that with increasing injected doses the rat is able to retain and utilize larger quantities of the amino acid. Possible explanations for these results are enumerated and the significance of these findings in relation to some previous studies is indicated.
Phosphorylase activation in stimulated dystrophic mouse muscle
Authors: Rulon R. R. , Schottelius D. D. , Schottelius B. A.
Published: December 2017

Phosphorylase a, t( a + b), and a: t x 100 values/g of wet muscle were determined on paired anterior tibial muscles from Bar Harbor strain 129 dystrophic and littermate control mice after tetanizing one member of the pair from 1/2–15 sec with an electrical stimulus. Rapid interruption of chemical events was accomplished by simultaneously quick-freezing resting and stimulated muscles at the last pulse from stimulator. Dystrophic muscle, with approximately one-quarter the phosphorylase t activity exhibited by control muscles, showed a significant decline in enzyme activity with age (60–115 days) which was not paralleled in the control muscle. Short bouts of stimulation (1/2–1 sec) produced greater a: t increases in dystrophic mice; intermediate stimulation (3–8 sec) produced similar a: t increases in both groups; and after 15 sec the control muscles showed greater increases in a: t values. Control muscles activate the enzyme in a progressive manner with lengthening stimulation periods; dystrophic muscles show a fluctuating activation.
Electrical interactions between normal and TEA-treated zones of squid axon
Authors: Oikawa T.
Published: December 2017

By stepwise injection of tetraethylammonium (TEA) chloride into a squid giant axon, it was shown that the degree of prolongation of the action potential by TEA depends on the length of the TEA-treated zone of the axon. Near the boundary between normal and TEA-treated zones of the axon, oscillatory potentials were often observed during the plateau of the prolonged action potential. It was shown that repetitive firing of impulses at the boundary originated in the TEA-treated zone, not in the normal zone. At the boundary between normal and TEA-treated zones, where the concentration of TEA changed continuously, there was a discontinuous change in duration of the action potential, indicating the existence of a sharp delineation between the zones developing long and short responses. Propagation of abolition of an action potential was demonstrated in uniformly TEA-treated axons.
Changes in renal function resulting from norepinephrine infusion
Authors: Langston Jimmy B. , Guyton Arthur C. , DePoyster James H. , Armstrong George G.
Published: December 2017

The experiments of this study show that intravenous infusion of norepinephrine has a direct effect on the kidneys of areflex dogs to cause a decrease in renal blood flow, glomerular filtration rate, and urinary output. However, when the infusion rate is below an average of 0.0006 mg/kg/min, the renal blood flow, glomerular filtration rate, and urinary output increase as a result of an increase in arterial pressure which accompanies the infusion of norepinephrine. Above this infusion rate, the direct effect of the norepinephrine on the kidneys is greater than the effect of the rising arterial pressure, thus causing the blood flow, glomerular filtration rate, and urinary output to decrease. The results from this study indicate that changes in renal arterial pressure result in very significant changes in renal blood flow, glomerular filtration rate, and urinary output in spite of the local autoregulation of renal blood flow.
Effect of chlorothiazide on renal juxtaglomerular cells and tissue electrolytes
Authors: Tobian Louis , Janecek Jeanette , Foker John , Ferreira Dorothy
Published: December 2017

Administration of chlorothiazide to rats for 9 weeks produces an increase of intracellular sodium and a decrease of intracellular potassium in skeletal muscle. However, in cardiac muscle, in the wall of mesenteric arterioles, in aortic wall, and in kidney there is no significant alteration in the amount of sodium, potassium, or chloride per unit of dry tissue weight. The water content of heart muscle, skeletal muscle, and kidney is not altered by chlorothiazide. The intracellular concentration of Na and K in heart muscle is likewise unaltered by chlorothiazide. However, chlorothiazide produces a highly significant 44% increase in the granularity of the juxtaglomerular cells. The data in general suggest that chlorothiazide decreases the volume of extracellular fluid, but does not reduce the content of intracellular Na. Extracellular K is reduced as well as the K inside skeletal muscle fibers. However, the amount of K inside cardiac muscle fibers is unchanged by chlorothiazide.
Effect of [NO3] on atrial action potentials and contraction as modified by [Na] and [Ca]
Authors: Peterson Nancy S. , Feigen George A.
Published: December 2017

Transmembrane potentials and contractility were measured in driven guinea pig atria according to conventional methods. The effects of nitrate were studied by substituting 40, 60, 80, and 100% of the chlorides with nitrates, and the influence of Ca and Na was determined by varying their ratio in the presence of 40% nitrate. The magnitudes of the resting potential, action potential, and overshoot were reversibly reduced; the rate of depolarization slowed; and the amplitude of contraction decreased as the proportion of nitrate to chloride was increased in the nutrient medium. In general, the initial phase of the repolarization was shortened, but the terminal phase was slowed. The duration of irresponsiveness was prolonged, and the maximum following frequency was reduced by nitrate. Calcium appeared to antagonize the deleterious effects of nitrate on all of the parameters except the resting potential, the negative afterpotential, and the irresponsive period.
Effects of serotonin on pulmonary blood volume in the dog
Authors: McGaff Charles J. , Milnor William R.
Published: December 2017

Changes in pulmonary blood volume produced by continuous intravenous infusion of serotonin (5-hydroxytryptamine) were measured in 16 experiments on ten dogs. Pulmonary mean transit time was measured by the dye dilution method, using consecutive injections into pulmonary artery and left atrium; pulmonary blood volume was calculated by multiplying this mean transit time by the cardiac output. Serotonin lowered pulmonary blood volume by an average of 2.9 ml/kg, or 26% of the control value ( P <0.001). Pulmonary vascular resistance increased 94 ru (resistance units) kg, and systemic vascular resistance fell 294 ru kg, effects similar to those reported by other investigators. The magnitude of the decrease in pulmonary blood volume indicates that a relatively large part of the pulmonary vascular bed is constricted by serotonin, and provides an example of shifting of blood from pulmonic to systemic circuits by reciprocal changes in the distensibility of these beds.
Arterial blood pressure waves in the absence of functioning aortic and carotid chemoreceptors
Authors: Armstrong George G. , Irby Larry S.
Published: December 2017

Dogs under pentobarbital anesthesia were subjected to chemoreceptor inactivation by intra-arterial injection of 0.5 n acetic acid close to the sites of the carotid and aortic chemoreceptors. Both damped blood pressure waves (elicited by abdominal pressure) and spontaneous sustained pressure waves of the Mayer type were demonstrated without functioning chemoreceptors. These waves could be demonstrated at all levels of mean arterial blood pressure at which the pressoreceptors were responsive. Since no waves of either the damped or sustained variety can be elicited when both the chemoreceptors and the pressoreceptors are destroyed it is concluded that the pressoreceptors alone are capable of supplying sufficient feedback to cause these arterial pressure waves.
Mesenteric, renal, and iliac vascular resistance in dogs after hemorrhage
Authors: Abel F. L. , Murphy Q. R.
Published: December 2017

Dogs were subjected to four consecutive bleedings of 5 ml/kg with an interval of 10 min between each. Blood flow in the renal, superior mesenteric, and common iliac arteries was measured with the electromagnetic flowmeter. Control blood flows averaged 448, 199, and 134 ml/min for superior mesenteric, renal, and iliac arteries, respectively. After 20 ml/kg blood was removed, superior mesenteric flow declined by 45%, renal by 52%, and common iliac by 40%. Calculated renal resistance increased little until after removal of 10 mg/kg blood, but there was a sharp increase after removal of 20 ml/kg. Mesenteric and iliac resistances increased from the onset of hemorrhage.
Relation between dietary cholesterol and bile acid excretion in the rat
Authors: Wilson Jean D.
Published: December 2017

The influence of dietary cholesterol on fecal excretion of bile acids has been studied in rats fed isocaloric quantities of purified diets that varied only in cholesterol content. Addition of dietary cholesterol clearly resulted in an increase in excretion of total bile acids, as well as in conversion of cholesterol-4-C14 to bile acid-C14. An acceleration in bile acid excretion as a result of cholesterol feeding was demonstrated to be independent of dietary cholic acid and to occur despite suppression of the bowel flora. These results suggest that not only does absorbed dietary cholesterol play a role in determining the rate of bile acid formation but that the adaptation of bile acid synthesis to cholesterol feeding may in part be a determining factor in the varying response of different species to cholesterol feeding.
Effect of high K, low K, and quinidine on QRS duration and ventricular action potential
Authors: Gettes Leonard S. , Surawicz Borys , Shiue James C.
Published: December 2017

Perfusion of isolated rabbit hearts with high potassium, low potassium, and quinidine solutions caused a diffuse widening of the QRS complex with no change in shape. These QRS changes were correlated with the magnitude and upstroke velocity of the ventricular transmembrane potential. An increase of QRS duration by 132% produced by high K was accompanied by a decrease of the action potential, resting potential, and upstroke velocity. A similar increase in QRS duration produced by quinidine was accompanied by a slow upstroke velocity but no change in magnitude of the action potential or resting potential. An increase of QRS duration by 49% produced by low K was accompanied by an increased action and resting potential, and upstroke velocity. We attributed the QRS changes produced by high K and quinidine, at least partly, to a slow conduction in the ventricle, caused by a slow upstroke velocity of the action potential. The QRS changes produced by low K could be explained by hyperpolarization. Early arrhythmias caused by low K were due to atrioventricular conduction disturbances.
Comparative effects of phlorizin and phloretin on glucose transport in the cat kidney
Authors: Chan Stephen S. , Lotspeich William D.
Published: December 2017

The net tubular reabsorption of glucose (TG) was measured simultaneously in both kidneys of the cat before, during, and after the infusion of small amounts of phlorizin and phloretin at constant rates into one renal artery. Experiments were performed at endogenous and elevated blood glucose levels. The results show that phlorizin blocks glucose transport across the renal tubule at concentrations in renal blood and tissue in the range of 10–5 to 10–7 m. These estimates agree with those for dog kidney in vivo and hamster small intestine in vitro. In addition to this high affinity of phlorizin for the tubular glucose carrier, the experiments also reveal the easily dissociable nature of the phlorizin carrier complex. When blood glucose is elevated the TG is even more sensitive to small concentrations of phlorizin. At all blood glucose levels the aglucone, phloretin, is at least ten times less effective in inhibiting TG than phlorizin itself. These findings are discussed in relation to critical groupings in the phlorizin molecule.
Renal tubular secretion of creatinine in the dog
Authors: O'Connell J. M. Brian , Romeo Joseph A. , Mudge Gilbert H.
Published: December 2017

Creatinine secretion in the dog has been studied under stop-flow conditions; 43 experiments were carried out in males and 14 in females. The mean free-flow and peak stop-flow creatinine U/P/inulin U/P in the males were 1.03 and 1.42, respectively. In 7 normal females the ratios were 0.95 and 1.14. Secretion could be demonstrated in the female if pretreated with testosterone. The results indicate creatinine secretion with proximal tubule localization. The nature of the transport system was studied and significant inhibition could be demonstrated with 2,4-DNP, organic mercurials, organic acids, and organic bases. The nature of the transport mechanism is discussed.
Movement of potassium between muscle and blood in response to respiratory acidosis
Authors: Ladé Roswith I. , Brown E. B.
Published: December 2017

Experiments have been performed on anesthetized dogs in order to study 1) the movement of potassium between the gastrocnemius muscle and blood during and following 2 hr of respiratory acidosis produced by breathing 30% CO2 in O2, and 2) the differences between skeletal and cardiac muscle with respect to potassium movement during the first 10 min of breathing CO2 and after return to air breathing. Plasma potassium concentrations were determined in blood samples drawn simultaneously from an artery and from either the vein draining the vascular bed of the skeletal muscle or the coronary sinus. It was found that skeletal muscle lost potassium during hypercapnia. The loss was evident much earlier and was greater if the muscle was stimulated to intermittent contraction than if it was resting. The heart began to gain potassium a few minutes after CO2 breathing began and lost potassium shortly after return to air breathing following 11 min of hypercapnia. There was no evidence for a contribution of skeletal muscle to the high transient elevation of the arterial potassium concentrations in the early posthypercapnic period.
Active transport of quaternary ammonium compounds into bile
Authors: Schanker Lewis S. , Solomon Harvey M.
Published: December 2017

The quaternary ammonium ion, procaine amide ethobromide (PAEB), administered intravenously (5 mg/kg) to rats with ligated renal pedicles, rapidly appears in the bile in high concentrations, both as free PAEB and as conjugated PAEB. During 1 hr after administration of the compound, the biliary concentrations of free as well as conjugated compound are about 80 times greater than the plasma concentrations. Raising the dose of PAEB does not result in an increased excretion of the compound, indicating that the excretion process is saturable. A number of quaternary amine compounds markedly depress the excretion of PAEB while others do not, suggesting a competition for transport and a certain degree of specificity for the transport process. The results indicate that the liver has an active secretory process for the transport of certain quaternary ammonium ions from blood to bile. The process appears to be different from that which actively secretes organic anions such as Bromsulphalein, bile acids, and fluorescein, since high doses of Bromsulphalein and sodium glycocholate do not inhibit the transport of PAEB.
Hippocampal or pyriform lobe damage in infancy and endocrine development of rats
Authors: Riss Walter , Burstein Stephen D. , Johnson Robert W.
Published: December 2017

Lesions were produced in the brains of male and female albino rats at 1 week of age. It was found that bilateral hippocampal damage is associated with diminished gonadal and adrenal development when that development is estimated by morphologic and behavioral indices (running activity). Only those female rats with bilateral degeneration of the dorsal fornix failed to exhibit cyclic running. Both male and female rats with considerable bilateral hippocampal damage showed diminished running, smaller-sized gonads, and larger thymus bodies at 75–80 days of age. On the other hand, male and female rats with bilateral damage to the pyriform lobe developed a precocious spurt in running activity. A spurt is normally associated with puberty. The question of whether the hippocampus and pyriform lobe should be regarded only as "centers" for trophic stimulation or suppression or whether they should be regarded as important links in circuits mediating an endocrine response to environmental conditions is discussed.
Lipid glyceride synthesis by rat skeletal muscle
Authors: Neptune E. M. , Sudduth H. C. , Brigance W. H. , Brown J. D.
Published: December 2017

In rat diaphragm, glyceride synthesis was observed to occur predominantly in the microsome fraction. In a phosphate buffered system containing CoA, ATP, Mg++, α-glycerophosphate, fluoride, and mercaptoethanol, palmitate-1-C14 was incorporated into phosphatidic acid, diglyceride, and triglyceride. Some of the enzymatic characteristics of the isolated organelle system are reported. Skeletal muscle from the back and legs of rats possesses a similar capacity in the microsome fraction; the latter system incorporated oleate-1-C14, linoleate-1-C14 and linolenate-1-C14 into glycerides. Both types of skeletal muscle have also a soluble enzyme that can synthesize glycerides.
Influence of aldosterone on isometric tension development in the rat heart
Authors: Ullrick William C. , Hazelwood Robert L.
Published: December 2017

Isometric twitch curves were recorded from preparations of rat heart trabeculae carneae removed from normal or adrenalectomized animals, or from normal animals injected for 3 days with saline or with 3 µg/day of d-aldosterone. Preparations from normal and from adrenalectomized animals were stimulated for 60 min in aldosterone-free Ringer's solution, or for 30 min in aldosterone-free Ringer's followed by 30 min in Ringer's containing 3 x 10–4 µg/ml of d-aldosterone. For a number of preparations from adrenalectomized animals the concentration of aldosterone was increased to 3 x 10–1 µg/ml. Regardless of treatment, all preparations were stimulated for a total of 1 hr at a rate of approximately 395/min; subsequently the recorded twitch curves were analyzed for peak tension development and for tension-time area. Although adrenalectomy tended to lower these variables of in vitro heart muscle performance, aldosterone, either administered in vivo or added directly to the isolated muscle bath, was without influence. It is concluded that aldosterone in the concentrations used does not alter the isometric tension characteristics of isolated rat heart muscle.
Interaction of insulin and chromium (III) on mitochondrial swelling
Authors: Campbell William J. , Mertz Walter
Published: December 2017

Swelling of rat liver mitochondria was significantly increased by 1.6 x 10–3 mm concentrations of insulin, but not with 1.6 x 10–4 mm insulin. 6 x 10–5 µmoles of chromium (III) per milliliter in the absence of insulin did not significantly increase swelling rates. Addition of insulin and chromium at concentrations which were ineffective by themselves, led to a considerable increase of mitochondrial swelling. On the basis of these and other data, it is proposed that trace amounts of chromium facilitate the tissue-insulin interaction by forming a complex with the intrachain disulfide of the hormone.
Tissue distribution, kinetics, and biologic half-life of Mg28 in the dog
Authors: Lazzara R. , Hyatt K. , Love W. D. , Cronvich J. , Burch G. E.
Published: December 2017

Mg28 of a high specific activity was used in these studies. It was rapidly injected intravenously into 12 dogs and the concentration-time course curves in plasma were obtained. Urinary and fecal excretion was followed in seven animals. The dogs were killed 7 min to 68 hr following injection. Seventy-four tissues were sampled and assayed for Mg28 concentration. Plasma Mg24 was determined by flame spectrophotometry. With these data it was possible to follow the concentration-time course of Mg28 in the various tissues as well as to calculate their "exchanging" Mg24 content and effective rates of exchange. A variation in the pattern of uptake and in concentration of exchanging Mg24 was noted among the different tissues. During the interval from 24–68 hr, body exchanging Mg24 space and mass were found to range from 3.2–3.8 liters/kg and 4.9–5.7 mEq/kg, respectively. The biologic half-life of Mg28 in the dog estimated from excretion data was 11 days.
Segmental vascular reactivity subsequent to sympathectomy
Authors: Reynolds David G. , Imig Charles J.
Published: December 2017

The effect of sympathectomy on the vascular bed of the dog was studied by analyzing segmental resistance changes occurring in response to intra-arterial injections of epinephrine and norepinephrine. The results indicate that the increase in total vascular bed reactivity is caused by sensitization of only the small vessel and venous segments. In an attempt to test the possibility that vascular smooth muscle develops supersensitivity in a manner similar to that which causes skeletal muscle supersensitivity, experiments were done on dogs which received intravenous injections of norepinephrine (0.5 µg/kg) every 8 hr for 2 weeks following sympathectomy. This procedure resulted in an increase in sensitivity of the arterial and venous segments in both the control and sympathectomized legs. Since this behavior was seen in both the denervated and innervated vascular beds no definite conclusions could be reached.
Effect of ryanodine on cardiac muscle
Authors: Nayler Winifred G.
Published: December 2017

Ryanodine (1 x 10–8 m) exerted a negative inotropic effect on toad ventricular muscle. The amplitude of contractions recorded from ryanodine-depressed ventricles were enhanced by raising the rate of stimulation, by increasing the extracellular Ca++ concentration, and by the addition of caffeine. The negative inotropic effect of ryanodine was reversed following perfusion with Tyrode solution containing 4 mm ethylenediaminetetraacetic acid.
Sodium, potassium, and intestinal transport of glucose, l-tyrosine, phosphate, and calcium
Authors: Harrison Harold E. , Harrison Helen C.
Published: December 2017

Everted loops of rat small intestine were incubated in media varying in their concentrations of sodium and potassium. Reduction of sodium concentration was effected by substitution of choline chloride in equimolar amounts for sodium chloride in the saline-bicarbonate buffer. Concentrative transport of glucose, l-tyrosine, inorganic phosphate, and calcium was measured by determination of the final ratio of the concentrations of the solute in serosal and mucosal fluids, and the increment of the solute in serosal fluid during incubation. Ca45 was used as an indicator of calcium distribution. The glucose, l-tyrosine, and inorganic phosphate transport systems require sodium, and at a submaximal concentration of sodium an increased concentration of potassium is inhibitory. The calcium transport system does not require sodium and in loops from the distal small intestine calcium transport is enhanced by reduction of sodium concentration in the medium. It is postulated that there is a common sodium-requiring system which is necessary for the linkage of metabolic energy to glucose, amino acid, and inorganic phosphate transport.
Influence of hemorrhagic shock on renal hemodynamics and osmolar clearance in the dog
Authors: Selkurt Ewald E. , Elpers Mary Jo
Published: December 2017

Renal hemodynamic alterations and accompanying changes in osmolar and free water clearance were examined during hemorrhagic shock in the dog. Deductions based upon application of p-aminohippurate and creatinine extractions to directly measured renal plasma flow indicated that hemodynamic alterations resulting from hemorrhage favored washout of kidney osmolar constituents; namely, some persistence of medullary blood flow was accompanied by severely curtailed glomerular filtration. Evidence for washout included the finding of concentrations of osmolality and sodium higher in the renal venous blood than arterial inflow. Turnover rates were calculated from the arteriovenous differences and plasma flow. The washout of osmolality and sodium coincided with the loss of concentrating power of the kidney, as manifested by such indications as shift in CHH2O from negative to positive values, and decrease in U/P of osmolality to ratios approximating 1.0 in the posttransfusion phase.
Intrinsic effects of heart rate on left ventricular performance
Authors: Mitchell Jere H. , Wallace Andrew G. , Skinner N. Sheldon
Published: December 2017

The effects of heart rate on left-ventricular performance were studied in an areflexic dog right-heart bypass preparation which allowed independent control of aortic pressure, cardiac output, and heart rate. When the heart rate was increased while stroke volume and mean aortic pressure were maintained constant the left-ventricular mean rate of pressure rise during isovolumic systole, the maximal rate of pressure rise during isovolumic systole, and the mean rate of ejection were all increased without any change in left-ventricular end-diastolic pressure. Further, it was shown that the left ventricle performed the same amount of stroke work over a wide range of heart rates without an increase in end-diastolic pressure in spite of the markedly shortened time available for performing this work. This was accomplished because of the increase in stroke power. These observations demonstrate that the performance of the left ventricle becomes intrinsically "faster" as the heart rate is increased. When the transient phenomena that occur when the heart rate is increased are considered, the fact that the same stroke work is produced over a wide range of heart rates without an increase in end-diastolic pressure indicates that the left ventricle has also become "stronger" than it would have been if the adaptive change had not occurred.
Pulmonary hemodynamics following acute atelectasis
Authors: Woodson R. Donald , Raab David E. , Ferguson D. J.
Published: December 2017

Locally induced alterations in pulmonary lobar blood flow and vascular resistance produced by atelectasis, hypoxia, or hypercarbia were studied in the autoperfused, innervated, separately ventilated right lower lobes of 14 dogs. Systemic effects of hypoxia or hypercarbia were excluded by shunting the lobar blood back to the vena cava; a second shunt between the internal mammary artery and the lobar artery permitted perfusion with either oxygenated or desaturated blood. Lobar blood flow was monitored with a magnetic flowmeter, and pressures were measured in the lobar artery, lobar vein, and femoral artery. Oxygen saturation was measured at these sites in nine of the dogs with a cuvette oximeter. Although systemic arterial pressure and oxygen saturation remained normal throughout these studies, hypoxia secondary to nitrogen ventilation produced average flow decreases of 19% and 14% with desaturated and saturated blood, respectively, and resistance increases of 26% and 15%. Atelectasis decreased flow by 37% and 23% and caused resistance to rise 93% and 65%. Ventilation of the lobe with 5% and 30% carbon dioxide in oxygen was without apparent effect.
Influence of fasting and refeeding on response of adipose tissue to insulin
Authors: Moore Richard O.
Published: December 2017

The glucose uptake, lactic acid production, and net gas exchange has been measured in adipose tissue from fed, fasted, or fasted and refed rats with and without insulin addition in vitro. Unstimulated adipose tissue from fasted and from fasted and refed rats showed a decreased capacity to take up glucose in vitro and a more negative net gas exchange than similar tissue from fed control animals. Insulin added in vitro increased the glucose uptake and CO2 excess in adipose tissue from fed, fasted, and refed rats, but the response with tissue from refed rats was several times that of the other groups. It is concluded that insulin is required for the marked increase in glucose metabolism associated with the refeeding regimen.
Pentylenetetrazol (Metrazol) shock in normal and adrenalectomized dogs
Authors: Swingle W. W. , Swingle A. J.
Published: December 2017

Metrazol-shocked nonadrenalectomized dogs exhibit a drastic though evanescent decline in plasma volume. A similar fall in plasma volume in the adrenalectomized dog persists and culminates in circulatory collapse unless C11 oxysteroids are administered. Loss of circulating fluid volume seems not to be due to shift of water into cells since the modest increase in hematocrit is insufficient to account for the volume change, nor can the volume decline be attributed to loss of vascular fluid into the extracellular compartment; this space decreased along with the plasma volume. The plasma volume loss of Metrazol-shocked dogs without adrenals seems due to intense, unrelieved vasoconstriction initiated by massive stimulation of the central nervous system by the drug, apparently resulting in closure of much of the vascular periphery, sequestration, and trapping of fluid and cells. Glucocorticoids somehow relieve the vasoconstriction and re-establish free blood flow at the periphery of the vascular tree. The fleeting elevation of plasma Na characteristic of Metrazol shock is independent of plasma volume changes and probably neurogenic in origin.
Quantitative study of intestinal fluid loss in irreversible hemorrhagic shock
Authors: Porciuncula Camilo I. , Crowell Jack W.
Published: December 2017

The effect of circulatory hypotension on the small intestine was studied in 42 dogs. The small intestine was clamped at the gastric and ileocecal ends, and the dogs were subjected to control studies or to hypotension of 30 or 40 mm Hg, with and without Dibenzylene, atropine, or vagotomy. The dry gut weight, the wet gut weight, the lumen contents, and the survival time were measured. The increase in gut weight was related entirely to the accumulation of fluid in the lumen of the gut. Vagotomy did not reduce the quantity of fluid in the gut lumen, but Dibenzylene reduced the amount and atropine abolished the accumulation of fluid. It is suggested that local irritation of the gut by anoxia causes secretion of fluid and hypermotility of the gut.
Effect of ureteral blockade on renal blood flow and urinary concentrating ability
Authors: Selkurt Ewald E.
Published: December 2017

Complete blockade of the ureter in dogs subjected to saline loading (0.85–10.0% NaCl) resulted in an increase in total renal blood during the period of blockade which appeared to be related to the antecedent diuresis and increment in ureteral pressure. This was accompanied by a progressive decrease in extraction of para-aminohippurate (PAH) and a greater decrease in creatinine extraction. The change in Epah showed a close inverse correlation to the change in renal blood flow (RBF). This afforded a possible explanation for the increment in RBF, for the increased perfusion of vascular circuits of the A-V communicating type would account for such a correlation. Evidence was supplied which suggested that such pathways involved the medullary vascular circuits. This was based on the observation that the concentrating ability of the kidney was impaired by the period of occlusion. The most likely mechanism for this would be maintained (or increased) vascular perfusion of the vasa recta system, in the face of markedly curtailed glomerular filtration, conditions resulting from ureteral blockade.
Membrane potentials in K-deficient muscle
Authors: Eckel Robert E. , Sperlakis Nick
Published: December 2017

Thirteen K-deficient and 14 pair-weighed control rats have been studied after 2 weeks on the experimental diets. Resting membrane potentials of skeletal muscle were measured immediately before killing the rats for plasma and muscle analysis. From the analytical data for Na, K, Cl, basic amino acids (BAA), and from plasma and intracellular pH studies in another series of rats studied concurrently, equilibrium potentials for Na, K, H, and BAA have been calculated and those from K-deficient animals compared with controls. The membrane potential is less negative in K depletion. All ions except K are closer to equilibrium across the K-deficient muscle membrane than they are in control tissue, provided BAA are considered to penetrate the membrane as univalent cations. A decrease in the fractional conductance of K and an increase in the fractional conductances of the other cations in K deficiency are inferred. The H+ ion is not in thermodynamic equilibrium across the membrane. The high concentration of BAA in K deficiency could be due to failure of a "BAA pump" or to a change in the passive permeability to the various ionic species of these zwitter ions.
Baroreceptor influence on postural changes in blood pressure and carotid blood flow
Authors: Abel Francis L. , Pierce John H. , Guntheroth Warren G.
Published: December 2017

The effects of 30° head-down and head-up tilting on mean systemic blood pressure, carotid blood flow, and heart rate were studied in 16 dogs under morphine and Nembutal anesthesia. The tilting procedure was further repeated after denervation of the carotid sinus and aortic arch baroreceptors and after administration of a dihydrogenated ergot alkaloid mixture (Hydergine). The results indicate that the drop in pressure in the head-down position is primarily due to baroreceptor activity and that the baroreceptors are necessary for compensatory vasoconstriction on head-up tilting. Carotid blood flow decreased in both tilted positions in the control animals; the possible relationship to cerebral blood flow is discussed.
Chorda tendinea tension
Authors: Salisbury Peter F. , Cross Cecil E. , Rieben P. Andre
Published: December 2017

Tension along chordae tendineae (CTT) was measured in absolute terms in situ and recorded throughout cardiac cycles. The transducers were installed without damage to the LV myocardium or its blood supply. CTT contours paralleled LV pressure traces only during isovolumic pressure development; CTT and LVP were sharply distinct or divergent during other periods of the cardiac cycle. The shape or magnitude of CTT could not be predicted from LVP traces. Hemodynamic and other factors influencing the various phases of CTT contours were investigated. Stroke volume, elastic storage capacity of the arterial tree, presence of a pericardial restraint, and coronary artery pressure influenced the magnitude and shape of CTT traces. Two types of heart failure were differentiated by specific CTT contours.
Response to exercise in dogs with cardiac denervation
Authors: Donald David E. , Shepherd John T.
Published: December 2017

Dogs with chronic cardiac denervation by the technic of regional neural ablation showed an unchanged capacity for work as measured by oxygen consumption. The relation of cardiac output to oxygen consumption during exercise remained unchanged from preoperational values. When the dogs started to run, the heart rate rose slowly over 1.5 min to reach a steady value proportional to the work performed. When exercise was stopped, the heart rate declined slowly. With mild exercise, the increase in cardiac output was mainly through stroke volume; with more severe exercise, increase in stroke volume and heart rate contributed equally, in contrast to the normal dog where the increase in rate predominates. Neither the pattern of the change in heart rate nor the plateau values were altered by adrenalectomy. The change in rate was not attributable to change in intravascular temperature. In an equivalent dose of base, norepinephrine caused tachycardia but little or no change in cardiac output, whereas epinephrine resulted in an increase in cardiac output with but a modest increase in heart rate.
An experimental evaluation of the relationship between hunger and gastric motility
Authors: Penick S. B. , Smith G. P. , Wieneke K. , Hinkle L. E.
Published: December 2017

Gastric contractions were studied in eight hungry men utilizing three methods of observation: 1) telemetry, employing a type 430 pressure transducer; 2) a gastric tube with a 50-ml balloon; and 3) inflation of a gastric balloon in 25-ml steps over a 20-min period. With telemetry, the observed rate of contraction after a 5-hr fast was 1.17 ± 3.22/hr over a 2-hr observation period. With the balloon, the rate of contraction in these same subjects over the same period was 12.3 ± .699, significantly greater than the rate obtained with the transensor ( P < .001). In the balloon-inflation experiments, the rate of contraction observed during the inflation period and for 20 min thereafter was 2.0 ± .62 2 hr after an intramuscular injection of 1 mg glucagon. Rate of contraction 2 hr after a placebo injection was 8.1 ± .91, significantly greater than after glucagon ( P < .001). The difference in contraction rate between methods 1 and 2 is ascribed to probable stimulation of contractions by the gastric tube and balloon. Glucagon, a known appetite depressant, markedly reduces the motor response of the stomach to inflation of a balloon 2 hr following intramuscular injection.
Bone metabolism in a mutant strain of rats which lack bone resorption
Authors: Vaes Gilbert M. , Nichols George
Published: December 2017

The metabolism in vitro of Ca, P, glycine, glucose, O2, and citrate by bone from normal rats and their littermates who suffered from a generalized defect in bone resorption (incisorless animals (ia)) have been compared. Defects in the oxidative metabolism of glucose and glycine and in the rate of O2 consumption have been found in bone from ia animals. Further, this defect has been traced to a partial block in the oxidation of citrate to α-ketoglutarate that could account for many of the phenomena observed. Bone from ia animals has also been found to maintain a higher concentration of Ca in its incubation medium at steady state than bone from normals. This phenomenon has been shown to be entirely the result of increases in the fraction of the total Ca concentration which depends on cellular metabolism and not to result from changes in the solubility of the bone mineral. Possible relationships between the cellular oxidative defect and the changes in Ca distribution in vitro have been examined in light of present knowledge.
Effect of potassium deficiency on action of chlorothiazide in the rat
Authors: Morrison Ashton B.
Published: December 2017

Chlorothiazide was administered to male rats which had been fed a potassium-deficient diet, and also to their pair-fed controls. Daily urine collections were carried out on the experimental and control rats before and during chlorothiazide administration. The drug caused a persistent increase in the daily urinary volume of the potassium-deficient rats, but only a transitory increase in the control rats. The striking increase in the daily urinary volume of the potassium-deficient rats was unaccompanied by an increase in solute output. The chlorothiazide did not affect the urinary-potassium loss in the potassium-deficient rats. No significant difference was found between the creatinine clearances of the potassium-deficient rats and their controls, nor did the creatinine clearances differ from those found in separate groups of potassium-deficient rats and controls to which chlorothiazide had not been administered. It is concluded that potassium deficiency does not interfere with the diuretic effect of chlorothiazide in the rat, but rather enhances it. The findings are consistent with the idea that chlorothiazide interferes with sodium reabsorption at a site proximal to that at which free water may be formed and at which complementary reabsorption of sodium takes place during the administration of chlorothiazide. An alternative explanation is that chlorothiazide may enhance the thirst of potassium-deficient rats.
Modification of serotonin and histamine release after E. coli endotoxin administration
Authors: Davis Richard B. , Bailey Walter L. , Hanson Norman P.
Published: December 2017

Platelet counts, serotonin, and histamine concentrations were studied after administration of E. coli endotoxin to rabbits in five experimental models. These included tolerance, immaturity, and pretreatment with heparin, warfarin, and epsilon-aminocaproic acid (EACA). Platelet counts and whole blood concentrations of serotonin and histamine were similar to values obtained in control rabbits given only endotoxin. Immediate increases in the concentration of serotonin and histamine in platelet-free plasma were inhibited in animals pretreated with warfarin and heparin. Tolerant animals, immature animals, and animals given EACA showed increases of plasma amines compared with saline-treated controls, but tolerant and immature animals showed significantly smaller elevations in plasma amines than adult controls given endotoxin. Elevations of plasma amines were absent 2-hr after endotoxin. The results are consistent with the hypothesis that rapid amine release in vivo occurs secondary to the action of thrombin on platelets. The occurrence of thrombocytopenia without increases in plasma amines was seen in certain cases. Tolerance and immaturity modify, but do not prevent immediate amine release.
Interrelations of arsenate and phosphate transport in the dog kidney
Authors: Ginsburg J. M. , Lotspeich W. D.
Published: December 2017

The relation between arsenate and phosphate transport in the dog kidney was studied by measuring the renal clearance of arsenate labeled with its radioactive isotope As74. The experiments were performed during osmotic diuresis induced by mannitol. The results demonstrate certain similarities in the transport of these ions. Arsenate undergoes a net tubular reabsorption which is inhibited as the plasma phosphate concentration is raised. The inverse relationship between arsenate transport and the plasma As:P ratio suggests a competitive mechanism for the interaction between the two ions Like phosphate, arsenate transport is inhibited by glucose and this effect is reversed by phlorizin. An important difference between arsenate and phosphate transport is the sensitivity of arsenate transport to urine flow. In vivo reduction of arsenate to arsenite and a net tubular secretion of arsenite has been observed. The results are discussed in terms of the known ability of arsenate to substitute for phosphate in biochemical reactions.
Central control of sympathetic cardiac augmentation in lower brain stem of the cat
Authors: Chai C. Y. , Share Norman N. , Wang S. C.
Published: December 2017

Fifty-three vagotomized cats under chloralose were studied for cardiac augmentation, cardioacceleration, and vasomotor reaction on direct stimulation of the medulla oblongata and via reflex activations. Cardiac augmentation as well as other cardiovascular responses could be induced on stimulation of the dorsal medulla or the central cut end of the sciatic nerves, or on occlusion of the carotid arteries. The augmentation and other responses remained essentially unchanged regardless of the presence or absence of the rostral neural structures, including the hypothalamus. The results confirm and support the concept that a central control mechanism for vasomotor reaction and cardioacceleration as well as augmentation resides in the dorsal region of the lower brain stem.
Aortic depressor fibers in the rat: an electrophysiological study
Authors: Krieger Eduardo Moacyr , Marseillan Ricardo Francisco
Published: December 2017

In 51 rats the distribution of the aortic depressor fibers which travel in the cervical region with the vagus, sympathetic, laryngeal, or as a separate aortic nerve was investigated by recording the action potential or by stimulating these nerves. A separate aortic depressor nerve was found in only 20% of the rats on the left side and in 5% on the right side. In these animals no depressor fibers were identified in the sympathetic trunk but the laryngeal nerves usually still exhibited depressor fiber activity. In those rats with no separate aortic depressor nerve the aortic fibers were present almost equally in the sympathetic trunk and laryngeal nerves, and on both sides of the neck. Only exceptionally was depressor activity found in the vagus trunk, and stimulation elicited depressor instead of pressor effects in 2 out of 12 rats. Optimal stimuli for obtaining hypotensive effects from the aortic depressor fibers were 80–150 per frequency and 1–2-msec duration.
Relationship of insulin and strophanthidin to myocardial metabolism and function
Authors: Regan Timothy J. , Frank Martin J. , Lehan Patrick H. , Hellems Harper K.
Published: December 2017

The relevance of changes in substrate and ion transport to left ventricular contractility alterations have been examined after insulin, strophanthidin, and their combination, using serial arterial-coronary sinus differences in intact anesthetized dogs. Insulin (0.1 U/kg) was infused into a left coronary artery catheter to minimize systemic changes, producing an accumulated left ventricular uptake of glucose, lactate, and potassium with a rise in respiratory quotient, without affecting pyruvate and free fatty acid extractions. There was no associated change in the d p/d tmax. of left ventricular pressure or in the duration of isometric contraction, used as indices of contractility. Acetyl strophanthidin, .03 mg/kg, produced a 60% increase in d p/d tmax. and significantly shortened isometric duration associated with egress of potassium from the myocardium. Insulin, given 25 min before strophanthidin to reduce K+ egress, failed to do so, but largely interfered with its contractile properties. This effect was also observed with p-chloromercuribenzoate, so that a SH-binding site would seem essential for the inotropic activity of strophanthidin.
Oxygen exchange of subcutaneous gas cavities in rats
Authors: Piiper Johannes
Published: December 2017

The O2 exchange of subcutaneous gas cavities initially filled with gas mixtures of varying O2 fraction was measured in unanesthetized rats breathing air. The net exchange rate of O2 was compared to the cavity-tissue O2 pressure gradient and to the carriage of O2 by the blood. The results suggest that diffusion, and not perfusion, was the rate-limiting process.