bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of reticuloendothelial-depressing substance in shock
Authors: Blattberg Benjamin , Levy Matthew N.
Published: December 2017

In an effort to find an in vitro method to detect the presence of reticuloendothelial-depressing substance (RDS), two tests were devised which measured phagocytic activity. One used carbon particles to measure phagocytosis and the other P32-labeled Escherichia coli. Neither method demonstrated an in vitro difference in granulopectic activity between dog plasmas from sham-operated and hemorrhagic-shock or superior mesenteric artery-occluded (SMAO) animals. An in vivo method was used in which the reticuloendothelial activity of the rat was measured in terms of the rate of clearance of injected carbon particles. Occlusion of the superior mesenteric artery of the rat led to the production of RDS. The RDS could be transferred to and demonstrated in a normal rat by means of SMAO rat whole blood, plasma, and dialysate of plasma, but not in RBC or plasma which had been dialyzed. Sham-operated animals were used as controls.
Bioassay of the prominent humoral agents involved in endotoxin shock
Authors: Vick James A.
Published: December 2017

The release of neurohumoral agents into the circulation following the administration of endotoxin has been studied. The use of the isolated vein in circuit with dogs administered a lethal dose of endotoxin permitted measurement of changes in vessel tension and afforded a continuous bioassay of the existing neurohumoral balance. Blocking agents were used to define the agent active at any one time. It appears that histamine or a compound similar to histamine is active in the first phase of shock, with catecholamines playing a predominant supportive role during the second hypotensive phase. The possibility of a parasympatheticlike response causing bradycardia and hypotension is also indicated.
A biochemical mechanism by which adrenergic mediators modify cardiac contraction
Authors: Stam Allan C. , Honig Carl R.
Published: December 2017

The influence of adrenergic mediators on the Mg-stimulated actomyosin ATPase of glycerinated cardiac myofibrils was analyzed. The mediators increased ATPase activity in the presence of soluble cardiac relaxing substance, but were without effect in its absence. Mechanical changes in the fibrils accompanied changes in ATPase activity. Threshold concentrations were: dl-isoproterenol = 3 x 10–8 m, l-epinephrine = 7 x 10–8 m, and l-norepinephrine = 6 x 10–7 m. Dichloroisoproterenol and dichloroepinephrine decreased ATPase activity in both the presence and absence of relaxing substance. The depressant effects of the dichloro analogs were not altered by epinephrine and isoproterenol, and could account for adrenergic "blockade" in vivo. Evidence of the specificity of myofibrillar enzyme, relaxing substance, and adrenergic stimulus is presented. Comparison of the properties of the cardiac inotropic adrenergic receptor with the properties of the soluble cardiac relaxing system suggests that the latter constitutes an intracellular site of action of adrenergic mediators in heart muscle.
Mechanism of natriuresis and diuresis during elevated renal arterial pressure
Authors: Selkurt Ewald E. , Womack Isaac , Dailey William N.
Published: December 2017

Continuous perfusion of the dog's renal artery at pressures averaging 200 mm Hg resulted in natriuresis, increased osmolar clearance, and increase in urine volume. The diuresis was typified by a decrease in TcHH2O, and in some instances positive free water clearance resulted. U/P of osmolality also declined, in some cases below unity. The above changes were observed in the absence of increase in glomerular filtration rate, as measured by creatinine clearance. The reductions in TcHH2O and U/P osmolality were correlated with decrease in the papillary to cortical sodium gradient. Thus, a washout of the osmotic gradient appeared to be the mechanism responsible for the decrease in ability of ADH to concentrate the urine. Because sodium and total osmolar load did not increase during the elevated pressure perfusion, decreased tubular reabsorption must have accounted for the natriuresis and enhanced osmolar clearance. It is speculated that the papillary sodium washout might indirectly influence sodium reabsorption by the ascending limb of the loop of Henle. The possibility is also considered that a mechanism of intrarenal hormonal regulation, responsive to changes in arterial pressure, might be responsible for the increased sodium clearance.
Renal transit times and distribution volumes of T-1824, creatinine, and water
Authors: Chinard Francis P. , Enns Theodore , Goresky Carl A. , Nolan Mary F.
Published: December 2017

The multiple indicator-dilution technique has been applied to a study of the vascular and extravascular volumes of the dog kidney in vivo. After probenecid, the venous outflow patterns of hippurate, iodopyracet, and chlorothiazide are nearly identical to those of creatinine. The patterns of fructose and diatrizoate are nearly identical to those of creatinine under control conditions. Creatinine's distribution is flow limited and not diffusion limited, and its accessible volume is the extracellular volume of the kidney. The distribution volume of inulin is smaller owing either to diffusion limitation or to an excluded volume phenomenon. At renal blood flows of 6 ml/sec per 100 g kidney, the vascular volume averages 20.5 ml blood and the interstitial fluid volume 20.0 ml equivalent plasma/100 g kidney. From experiments with labeled water, cell water averages 38.7 g/100 g kidney. The ratio of interstitial fluid to cell water averages 0.56. The distribution volume of sodium falls between that of water and that of creatinine. Some limitations of indicator-dilution experiments are indicated.
Respiration and oxidation of various substrates by ileum in vitro
Authors: Neptune Edgar M.
Published: December 2017

The respiration of ileum from the rabbit, monkey, hamster, guinea pig, and rat in vitro was studied. Measurements were also made of the rate of oxidation of labeled glucose, glutamine, acetate, and palmitate to C14O2 by ileum in these species. Added glutamine and acetate are oxidized at a faster rate than added glucose by rabbit ileum. The guinea pig and monkey ileum gave values similar to the rabbit except that the guinea pig tissue had a higher rate of respiration. The hamster and rat ileum both oxidized glutamine and glucose at nearly the same rate. All species oxidized acetate vigorously. All species oxidized labeled palmitate which was added at low concentrations. Mucosal cells of rabbit ileum oxidized the various substrates at rates that were proportional to full-thickness ileum. It is concluded that ileum from various species of animals can oxidize a number of different substrates in vitro. There are differences in rates of oxidation by various species.
Effects of altitude acclimatization and deacclimatization on bone and marrow volume in dog
Authors: Gong Joseph K.
Published: December 2017

Skeletons of altitude-acclimatized, altitude-deacclimatized, and sea-level control dogs were completely analyzed for water, fat, and nonfatty organic and inorganic fractions. The total skeletal and marrow volumes as well as their contents were calculated and compared. Neither the marrow volume nor the bone (trabecular and cortical) volume was affected by the altitude changes. The relative distribution of marrow and bone in the various parts of the skeleton was also unchanged. Marrow fat in the whole skeleton as well as in the individual parts of the skeleton was lowered on acclimatization and increased on deacclimatization. Of the fat lost, one-third was from the flat bones while one-half of the fat deposited on deacclimatization occurred in flat bones. The marrow water as well as the functional marrow (fat-free, by definition) in either the whole or the various parts of the skeleton was increased on acclimatization and decreased on deacclimatization.
Oxidative phosphorylation in cardiac infarct. Effect of glucose-KCl-insulin solution
Authors: Calva Edmundo , Mujica Adela , Bisteni Abdo , Sodi-Pallares Demetrio
Published: December 2017

Myocardial infarction was produced in dogs by ligature of the anterior descending coronary artery. Sarcosomes were isolated from normal and infarcted tissue. Oxygen consumption was followed polarographically and adenosine triphosphate was measured as glucose 6-phosphate. One group of animals received a continuous infusion of glucose for 12 hr; another group received "polarizing solution" (glucose-KCl-insulin). Sarcosomes from the first had a low oxygen consumption, no respiratory control, and no oxidative phosphorylation. In contrast, the administration of glucose-KCl-insulin solution maintained practically within normal limits these functional aspects of the sarcosomes. The reversal of electrocardiographic abnormalities by the administration of the polarizing solution coincided with improvement of such biochemical functions. Anesthesia and surgical handling did not appear to modify the behavior of the sarcosomes.
Responses of isolated perfused arteries to catecholamines and nerve stimulation
Authors: Rogers Larry A. , Atkinson Richard A. , Long John P.
Published: December 2017

An isolated preparation of the dog's mesenteric artery with branching small resistance vessels and sympathetic nerves attached has been devised. The branching arterial segments were perfused by a constant-flow technique; the pressor responses to intra-arterially injected catecholamine and to nerve stimulation were recorded. The preparation gave reproducible pressor responses to injected catecholamine and to nerve stimulation for periods of several hours. Decreasing the temperature or increasing the pH (by decreasing CO2 in the gas mixture) of the vessel bath increased arterial smooth muscle tone and potentiated the pressor responses to injected catecholamine and to nerve stimulation. Increasing the temperature of the bath decreased the tone and reactivity of this preparation. Low-frequency continuous nerve stimulation potentiated the responses of this preparation to intra-arterially injected catecholamines.
Platelet aggregation and inactivation and inhibition of adenosine diphosphate
Authors: Constantine Jay W.
Published: December 2017

Adenosine diphosphate (ADP)-induced platelet aggregation in rabbit and rat platelet-rich plasma was used as an index of ADP activity, and as a means of detecting inhibitory activity to ADP. Inactivation of ADP occurred in rabbit and rat plasma, and ADP inhibitory activity appeared in the plasma of both species following incubation with the nucleotide. Platelets were not required for the inactivation of ADP, or for the formation of inhibitory activity, but both processes were enhanced in the presence of platelets. ADP inhibitory activity in rabbit and rat plasma did not resemble that of exogenous adenosine or AMP. The results do not support the assumption that known products of the degradation of ADP are solely responsible for the inhibitory activity. It is concluded that the inhibitory activity may be due to unknown products of the degradation of ADP, or to a factor elicited in response to the presence of ADP in plasma.
Effect of fibrin and fibrinogen proteolysis products on clot physical properties
Authors: Hirsh Jack , Fletcher Anthony P. , Sherry Sol
Published: December 2017

Clot formation in the presence of plasmin-stable proteolysis products of fibrinogen and fibrin was studied by thromboelastography and by a modified light-scattering method. Thromboelastography demonstrated that both types of proteolysis products lengthened the "r" and "k" values and decreased "ma" values; these findings were interpreted as demonstrating delayed fibrin formation and reduced clot tensile strength. Light-scattering measurements demonstrated that both sets of products inhibited fibrin polymerization rates. Neither qualitative nor quantitative differences were detected between the actions of fibrin or fibrinogen proteolysis products, and the degree of alteration in functional clotting parameters and in clot tensile strength was proportional to proteolysis product concentration. Platelet function tests, including clot retraction tests, microscopic and turbidometric measurement of thrombin, and ADP-induced platelet aggregation, were uninfluenced by plasmin-stable proteolysis products. Most conventional plasma fibrinogen assays yielded artifactually low values when the plasma contained proteolysis products, but the accuracy of a modified Ratnoff and Menzie procedure was unaffected in these circumstances. A rapid immunological assay ( Fi test) also proved satisfactory.
Vagal gastric secretory stimulation by 2-deoxy-d-glucose
Authors: Hirschowitz Basil I. , Sachs George
Published: December 2017

Powerful vagal stimulation of gastric secretion was produced in dogs by the administration of 50–200 mg/kg 2-deoxy-d-glucose (2-DG) The secretion could be entirely prevented or immediately abolished by atropine injection, indicating one link which is apparently cholinergic. Studies with glucose, mannose, fructose, galactose, or 3-O-methylglucose injected before or subsequent to the administration of 2-DG indicated that the vagal secretory center is specifically glucose and mannose dependent. 2-DG appears to act by the formation of nonmetabolized 2-DG-6-phosphate resulting in effective cytoglucopenia. While apparently stimulating gastric secretion in the same way as insulin hypoglycemia, 2-DG appears to have definite advantages of reliability and reproducibility. The vagal center appears to be dose responsive and not an all-or-none system, and stimulates all elements of gastric secretion by a single pathway.
Influence of protein and amino acids on food intake in the rat
Authors: Krauss Ronald M. , Mayer Jean
Published: December 2017

The depression of food intake by high levels of dietary protein and by an excess of l-leucine in a low-protein diet was found to be independent of the presence of the hypothalamic mechanism regulating food intake. At extremely high levels of protein or amino acid intake, the amount of diet ingested was restricted to a similar level in normal and hyperphagic rats. The fact that hyperphagic rats consumed a relatively constant amount of casein in diets containing 60– 90% of protein suggested the possibility that a physiological "safety valve" operated to limit dietary intake so that protein intake did not exceed a certain threshold. An accumulation of amino acids that could not be metabolized or diverted into protein synthesis may have mediated the appetite effects. This suggestion was consistent with the finding that prefeeding high levels of protein (40 or 60% of casein), a procedure which is known to enhance amino acid catabolic activity, temporarily eliminated the appetite depression normally caused by subsequent ingestion of a high-leucine diet.
Induced change in heart metabolism as a primary determinant of heart performance
Authors: Bacaner Marvin B. , Lioy Franco , Visscher Maurice B.
Published: December 2017

In 65 isolated dog hearts, left ventricular isometric developed tension (LVDT) or isotonic shortening (LVS) were measured at various levels of coronary blood flow (CBF) and heart load. It was found that imposed changes in CBF (over a wide range) 1) caused directionally similar changes in LVDT (or LVS) and O2 consumption at any given heart load (metabolic effect); 2) governed the magnitude of change in LVDT or LVS in response to an altered load (Starling effect). In some hearts autoregulation of CBF occurred which obscured but did not obliterate the effect. Autoregulation of CBF could be diminished or abolished by lowering arterial O2 saturation and restored by resaturation. It is suggested that CBF rate may be an important normal determinant of cardiac work capacity and performance by regulating the delivery rate of O2 and substrate as well as removal rate of CO2 and other metabolites in various parts of the myocardium. Possible defects in experiments reported by others failing to show a dependence of work performance on CBF rate are mentioned.
Carotid chemoreceptor stimulation and ventricular performance
Authors: De Geest Hilaire , Levy Matthew N. , Zieske Harrison
Published: December 2017

In paced, canine, innervated, isovolumetric, left ventricle preparations in which the lungs were deflated, hypoxia of the isolated carotid sinus region usually elicited a negative inotropic effect on left ventricular performance, as assessed by peak pressure development. After vagotomy, a slight increase in peak left ventricular pressure was usually evoked. It is concluded that the primary reflex cardiac effect of carotid chemoreceptor stimulation consists of an increase in vagal tone. When the vagi are intact this augmentation of parasympathetic activity is primarily responsible for the depression of ventricular performance, and for bradycardia in the unpaced heart. After vagotomy, carotid chemoreceptor stimulation produces a slight increase in sympathetic activity under the conditions of the present study. This effect may actually be secondary to excitation of the respiratory centers, which results from chemoreceptor stimulation.
Comparative activity of thrombin on substituted arginine and lysine esters
Authors: Sherry Sol , Alkjaersig Norma , Fletcher Anthony P.
Published: December 2017

A number of biologically important proteolytic enzymes, particularly those involved in the reactions of blood coagulation and fibrinolysis, have the ability to hydrolyze synthetic esters of the basic amino acids, arginine, and lysine. Though synthetic amino acid esters have been used for the study of the reaction kinetics of these enzymes and for assay purposes, relatively little has been done to characterize these enzymes on the basis of their differing abilities to hydrolyze synthetic substrates. Utilizing a variety of comparably substituted arginine and lysine esters, observations were made on the reaction kinetics of several basic amino acid esterases; significant differences were noted among these enzymes, sufficient to establish their separate identity. Further characterization of the reaction of thrombin with synthetic substrates revealed that this enzyme readily hydrolyzes various substituted lysine esters as well as arginine esters. The highest Vmax was observed for the throm-bin-carbobenzoxy-lysine methyl ester reaction but the greatest affinity was observed with benzoyl-arginine methyl ester. The data also clearly establish enzymatic differences between human and bovine thrombin, and between the latter and bovine plasma thrombokinase.
Micropuncture study of proximal renal tubular chloride transport during hypercapnea in the rat
Authors: Kashgarian Michael , Warren Yves , Levitin Howard
Published: December 2017

The electrical potential difference and the concentration of chloride in tubular fluid and plasma were measured in stopped-flow microperfusion of the proximal tubule of rats breathing either air or 12% CO2 in air. Perfusion with 10% PVP completely stopped net transtubular fluid movement. Chloride was not in electrochemical equilibrium under these conditions and hypercapnea increased the concentration of chloride in tubular fluid relative to that in plasma. This suggests that the net reabsorption of chloride must overcome a force which moves chloride into the tubular lumen. An anion pump is postulated which secretes chloride into the tubular lumen and is linked to acidification of proximal tubular fluid.
Effect of excitement on coronary and systemic energetics in unanesthetized dogs
Authors: Rayford Claudia R. , Khouri Edward M. , Gregg Donald E.
Published: December 2017

The effect of excitement on phasic aortic pressure and flow, phasic left coronary flow, and myocardial metabolism has been studied in dogs 1–8 weeks after implantation of appropriate flowmeters and other devices. The rapid increase in heart rate and mild increase in blood pressure in the first few seconds tend to maintain coronary flow per minute despite a decrease in stroke cardiac output and coronary flow throughout the cardiac cycle. The main response is a delayed rise in coronary flow per minute resulting from further elevation of heart rate and blood pressure, a moderate increase in stroke cardiac output and a sizeable increase in stroke coronary flow, the latter being divided fairly evenly between systole and diastole. From 60 to 90% of the increase in mean coronary flow arises from the increase in stroke coronary flow, and the remainder from the increased number of heartbeats per minute. Some of the possible mechanisms concerned are discussed.
Observations on adrenergic innervation of dog heart
Authors: Dahlström A. , Fuxe K. , Mya-Tu M. , Zetterström B. E. M.
Published: December 2017

The adrenergic innervation of the dog heart was studied by a histochemical fluorescence technique. The SA and AV nodes are extensively innervated by adrenergic fibers. Certain parts of the atria, auricles, and ventricles show a rich adrenergic innervation, while other parts of the same tissues are very deficient, suggesting that the sympathetic innervation to the heart is "patchy." The adrenergic innervation of the Purkinje cells is likewise very sparse, large numbers of cells showing no adrenergic innervation at all. It is suggested that the adrenergically innervated Purkinje cells exhibit a form of "pacemaker" activity.
Myocardial potassium balance during cardioaccelerator nerve and atrial stimulation
Authors: Sybers R. G. , Sybers H. D. , Helmer P. R. , Murphy Q. R.
Published: December 2017

By following changes in arterial-coronary sinus plasma potassium concentration differences, the myocardial potassium balance was studied during the increased heart rate produced by cardioaccelerator nerve or right atrial stimulation. With cardioaccelerator nerve stimulation there was an initial loss of myocardial potassium of brief duration, followed by an uptake for the duration of the stimulation. Atrial stimulation leads predominantly to a loss of myocardial potassium, particularly when the reflex effects of marked cardiac acceleration were minimized by cardioaccelerator nerve excision and support of venous return by abdominal binding. It is suggested that the chronotropic action of cardiac sympathetic nerves tends to cause a loss of potassium, but that this is normally circumvented by some other action of the nerves in promoting potassium uptake.
Methodologic variability of pulmonary-left heart blood volume by dye dilution in dogs
Authors: Jortner R. , McNally E. , Weisberg H.
Published: December 2017

This study was done in order to estimate the methodologic variability (MV) of a dye-dilution technique for determining the combined pulmonary-left heart volume. "Clusters" consisting each of four slug curves shot in rapid succession were obtained under conditions in which great effort was made to suppress hemodynamic variation. Six clusters, during which the mean aortic and mean pulmonary artery pressures, the left ventricular end-diastolic pressure, heart rate, and cardiac output remained relatively stable, were selected for analysis on the assumption that the true volume under study also varied but little. In these selected clusters the variation in calculated volume was determined, and this variation considered to be the MV. The value for MV thus obtained is of course an overestimate and, expressed as one standard deviation, ranged from 1.6 to 6.6%, and averaged 3.8% of the mean value. The meaning and applicability of methodologic variability is discussed. A convenient method for calculating mean transit time from slug data is described.
Chylomicron-lipid-splitting activity in homogenates of rabbit polymorphonuclear leukocytes
Authors: Elsbach Peter , Kayden Herbert J.
Published: December 2017

Evidence for hydrolysis of chylomicron-triglyceride was sought in homogenates of polymorphonuclear leukocytes obtained from rabbit peritoneal exudates. Such activity was found using chylomicra from human thoracic duct lymph. Release of fatty acid was greatest at pH 4.8 and a triglyceride concentration of 5 mm. Most of the activity was found associated with particulate fractions of the homogenate. Almost 50% of the total activity occurred in association with the granules (lysosomes) of the leukocytes. Repeated freezing and thawing of whole homogenate or its particulate fractions resulted in an increase in activity of approximately 50%. The activity was inhibited by phosphate and NaF but not by protamine or iodoacetate. It is concluded that homogenates of leukocytes contain an acid glycerolester hydrolase, which splits triglycerides of naturally occurring lipoproteins. The intracellular distribution of the activity suggests that it is at least in part lysosomal in origin.
Effect of acute hypernatremia, hyponatremia, and acidosis on bone sodium
Authors: Forbes Gilbert B. , Tobin Richard B. , Harrison Anne , McCoord Augusta
Published: December 2017

Acute experiments were carried out in cats and rabbits in which a sample of cortical bone was taken prior to and at the conclusion of the experimental procedure. Thus each animal served as its own control. Hyponatremia caused a decrease in bone Na and hypernatremia an increase. The observed changes could be accounted for entirely by that portion of bone Na which is associated with bone water in equilibrium with extracellular fluid. In these and additional experiments in the rat, acidosis unassociated with hyponatremia did not mobilize Na from bone.
Metabolism of thyroid hormones and some derivatives in isolated, perfused rat liver
Authors: Flock Eunice V. , Owen Charles A.
Published: December 2017

The isolated, perfused rat liver has been used to study the metabolic pathways of I131-labeled l-thyroxine (T4), l-3,5,3'-triiodothyronine (T3), their partially deiodinated derivatives, and d-thyroxine. l-Thyroxine was metabolized less rapidly than the l-thyronines with fewer iodine atoms. l-T4 accumulated in the liver more rapidly than l-3,3',5'T3 or l-3,3'T2 but less rapidly than l-3,5,3'T3 or d-T4. Conjugation with glucuronic acid proceeded in the liver most rapidly from 3,5,3'T3 and at much lower rates from d-T4, l-T4, l-3,3',5'T3, and l-3,3'-diiodothyronine (T2). Deiodination of l-3,3',5'T3 and l-3,3'T2 proceeded most rapidly.
Intramuscular pressure changes during contraction in relation to muscle spindles
Authors: Bridgman Charles F. , Eldred Earl
Published: December 2017

Pressure changes induced by stretch or contraction of the tennuissimus and calf muscles of the cat were studied in relation to postulated mechanism for pressure activation of muscle spindles. Pressure was monitored through tubing filled with low-viscosity silicone oil connecting a hypodermic needle tip to a low-volume displacement transducer. Distribution of changes was detected by moving the needle to different sites in the muscle. Both stretch and total contraction produced essentially uniform pressure increases throughout the muscle. In fractional contractions, including those of single motor units, the center of contraction was marked by strong increases in pressure and the peripheral zones by weaker biphasic and negative changes. Over much of the muscle no change was detectable during contraction of a motor unit. In general the strongest gradient of pressure change seemed directed perpendicular to the axis of the contracting unit. It was concluded that conditions favoring the operation of a pressure mechanism in the spindle might exist in subtotal, but not in total contraction of the muscle.
Metabolism of radiocopper (Cu64) in the rat
Authors: Owen Charles A.
Published: December 2017

About 100 µg of copper as cupric acetate-Cu64 was given iv to adult, male rats. Maximal concentrations of Cu64 were reached quickly in the excretory organs—liver, kidney, and gastrointestinal tract—which then slowly released their radioactivity. In most of the other organs a progressive accumulation of Cu64 began after the disappearance of most of the nonceruloplasminic Cu64 from the plasma and after ceruloplasmin-Cu64 emerged in the plasma, suggesting that ceruloplasmin may be the copper donor for the tissues. The disappearance of plasmatic Cu64 tended to parallel that from the liver after the first 48 hr.
Mechanism of increase of myocardial oxygen uptake produced by catecholamines1
Authors: Klocke Francis J. , Kaiser Gerard A. , Ross John , Braunwald Eugene
Published: December 2017

The relative roles of augmented hemodynamic performance and direct stimulation of oxidative metabolism in mediating the increase of myocardial oxygen uptake (MVo2) produced by catecholamines have been examined in an isolated canine heart preparation. The responses of MVo2 to graded doses of isoproterenol, norepinephrine, or epinephrine were determined before and after the induction of cardiac arrest with potassium. Although increases of MVo2 occurred in the arrested state with the larger doses of the amines, they constituted only a small fraction, generally between 5 and 20%, of the increases produced by the same doses of amines when the hearts were beating. It is concluded that while large doses of catecholamines can increase oxidative metabolism of the nonbeating heart by a small amount, the increases of MVo2 produced by catecholamines in the beating heart are due in large part to the hemodynamic alterations which the amines induce.
Production and abolition of alternation in mechanical action of the ventricle
Authors: Gilbert J. L. , Janse M. J. , Lu H. H. , Pinkston J. O. , Brooks C. McC.
Published: December 2017

Persisting alternation in mechanical response of the ventricle, pulsus alternans, develops when the heart is driven above certain rates. This critical rate varies, but tends to occur between rates of 200 and 300 beats/min. The ventricle can be driven slightly faster (10–20 beats/min) by direct than by indirect drive, through atrial electrodes, without showing pulsus alternans. There is a rate "threshold" for persisting alternation which represents the rate limits of compensation. Alternation appears at lower rates but the contractile process can gradually accelerate and alternation disappears even in denervated hearts and after adrenalectomy. Slower progressive accelerations delay onset of pulsus alternans and compensation occurs more quickly than when stepwise rate changes are made. Fast drives above the threshold for pulsus alternans can produce some additional acceleration of the contraction-relaxation process: if the rate is reduced to a level which previously produced a persisting alternation, pulsus alternans does not occur for a number of seconds. The resemblances of these phenomena to "treppe" and "postextrasystolic potentiation" and implications relative to catecholamine release and action are discussed.
Effect of cervical vagosympathectomy on myocardial catecholamine concentration
Authors: Jellinek Max , Kaye Michael P. , Kaiser George C. , Cooper Theodore
Published: December 2017

Dogs which survived a bilateral cervical vagosympathectomy showed a striking reduction in catecholamine concentration of right atrial tissue. Significant decreases in catecholamine concentration were noted also in the tissues of both ventricles and the interventricular septum. Unilateral cervical vagosympathectomy, either right or left, was not followed by a statistically significant decrease in the concentration of cardiac catecholamines. The cause of the depletion after bilateral cervical vagosympathectomy is not clear. It may be due to destruction of intracardiac adrenergic nerves or a relatively increased utilization of catecholamines, which exceeds the capacity of the cardiac tissues to synthesize, take up, or bind these substances. The concentrations of cardiac histamine and nitrogen were unaffected by these operative procedures.
Role of reflexes following myocardial necrobiosis
Authors: Ascanio G. , Barrera F. , Lautsch E. V. , Oppenheimer M. J.
Published: December 2017

Intracoronary administration of hexachlorotetrafluorobutane (Hexa) into non-thoracotomized dogs produced a statistically significant decrease in left ventricular systolic pressure (LVSP), mean femoral arterial blood pressure (MFAP), first derivative of left ventricular pressure pulse (dP/d t), total peripheral resistance (TPR), and cardiac output (C.O.) lasting up to 1 hr after injection. Femoral vascular resistance decreased during the first 3 min after production of necrobiosis. Fifty percent of the dogs died of ventricular fibrillation (VF) after Hexa infarction. Prereserpinized dogs did not show significant changes in the parameters which were significantly changed in normal dogs after Hexa necrobiosis except in the case of VF which was almost absent in this group. Bilateral vagotomy prior to Hexa administration prevented most hemodynamic changes after necrobiosis whereas atropine did not. Bilateral vagotomy and atropine 1 hr after necrobiosis increased MFAP, dP/d t, LVSP, C.O., and TPR. Apparently excitatory efferent sympathetic activity on heart and femoral arterial vessels is reflexly inhibited by the effects of intracoronary injection of Hexa. The afferent pathway is via the vagus nerve.
Correlation of motility and gas collection from goat rumen
Authors: McCauley E. H. , Dziuk H. E.
Published: December 2017

Using three trained, fistulated goats in standing and recumbent positions, ruminal gas accumulating in the top of the dorsal sac was collected and measured during resting and ruminating activities. Collectible gas accumulation (CGA) rates were higher during rumination than during rest but were reduced below resting rates during ruminal atony induced by administration of atropine. Three conditions which resulted in abrupt increases in CGA rates were: 1) ruminal contractions following a period of atony, 2) changing from rest to rumination, and 3) vigorous somatic movements. At an intraruminal pressure of 15 cm water below atmospheric pressure, ruminoreticular cyclic frequency, secondary ruminal contraction frequency, and the ratio of the number of secondary to primary ruminal contractions were reduced. The observations indicate that reduced eructation rates during periods of rest result from a reduction in gas accumulation in the dorsal rumen because of a temporary storage of gas at other sites.
Digestion of purine ribonucleotides by intestinal enzymes of the developing rat fetus
Authors: Wilson D. Wright , Wilson Helene C.
Published: December 2017

Small segments of intestine from fetal rats were incubated in the presence of guanosine monophosphate (GMP) or adenosine monophosphate (AMP) and the products of hydrolysis identified by paper chromatography. All of the enzymes required to decompose GMP and AMP to uric acid and allantoin that were found in the adult intestine were also found in the 19-day fetal intestine. These were: nucleotide phosphatase, adenosine deaminase, guanosine-inosine phosphorylase, guanase, xanthine oxidase, and presumably uricase. The 16-day fetal intestine lacked xanthine oxidase, at least in sufficient amount to give ultraviolet spots on the chromatograms, for xanthine and uric acid. In one experiment on a 15-day fetus, inosine phosphorylase was also lacking, and one on a 13-day fetus gave positive evidence of only nucleotide phosphatase. It is inferred that there is a gradual development of these enzymes in the fetal life of the rat, the ones decomposing the more complex molecules of the nucleotides and the nucleosides appearing earlier than those decomposing the bases. There are, however, no data from these experiments to indicate how early uricase is formed, since uric acid was not found among the decomposition products of GMP or AMP digestion until the 19th day.
Renal tubular transport of water, solute, and PAH in rats loaded with isotonic saline
Authors: Cortney Marshall A. , Mylle Margaret , Lassiter William E. , Gottschalk Carl W.
Published: December 2017

Renal tubular transport of water, osmotically active solute, and PAH were studied with micropuncture methods in anesthetized rats loaded with a volume of 0.9% sodium chloride solution equivalent to 10% of their body weight. Inulin clearance and urine flow were greatly elevated above values in nondiuretic animals, but there was little change in PAH clearance. F/P inulin-C14OOH ratios indicated that 42% of the filtered water and solute was reabsorbed along the proximal convolution, a lower fraction than is found in nondiuretic and hypertonic saline-loaded rats. This indicates that the rate of solute and water reabsorption in the proximal tubule did not increase in proportion to the increased filtered load, and it was, in fact, similar to that in nondiuretic rats. Intravenous administration of vasopressin and aldosterone had no demonstrable effects on solute or water reabsorption. F/P PAH/inulin ratios demonstrated that PAH secretion occurred along the proximal tubule, but probably in no other portion of the nephron.
Summation of bilateral carotid sinus signals in the barostatic reflex
Authors: Sagawa Kiichi , Watanabe Keizo
Published: December 2017

In order to investigate the manner in which bilateral carotid sinus pressoregulatory signals are summated in the reflex loop, the relationship between systemic arterial pressure changes (ΔSAP) caused by unilateral and bilateral intrasinusal pressure changes (ΔISP) in the carotid sinuses was examined in 27 dogs. ISP was altered by either isolating the sinuses and changing the perfusion pressures (8 dogs) or occluding the common carotid arteries (19 dogs). The results from the isolated perfused sinus experiments showed conformity between the sum of two ΔSAP's during left- and right-side ISP changes and the actual ΔSAP during bilateral ISP change. Accordingly, it is concluded that the process of summation of carotid sinus static pressoregulatory signals is one of simple addition, at least within the investigated physiological pressure range. Other important findings were as follows: a) The mean open-loop, over-all gains of the left and right unilateral sinus pressoreceptor reflexes were –0.40 and –0.68, respectively, as measured in the isolated sinus experiment using small input pressure changes, the left-to-right gain ratio being 0.59; similar values were found in the carotid occlusion experiment. b) The bilateral over-all reflex gain was –0.99, and vagotomy increased this to –1.51, which is probably a value close to the true static open-loop gain of the carotid sinus pressoregulatory reflex in the normal pressure range of anesthetized dogs.
Membrane potentials of salivary gland cells of rat
Authors: Schneyer L. H. , Schneyer C. A.
Published: December 2017

Transmembrane electrical potentials were recorded from cells of rat salivary glands in vivo, using microelectrodes. The mean (±se) from 61 impalements of unstimulated submaxillary cells was 28 ± 1.4 mv. In submaxillary gland, acinar cells and cells of granular tubules account for approximately 70 and 30%, respectively, of all secretory elements. Dividing the range of submaxillary potentials at 35 mv gave two groups with new means of 23 ± 1.0 and 41 ± 0.6 mv, in which were contained 70 and 30%, respectively, of all values. Potentials in submaxillary gland from which granular tubules had been caused virtually to disappear (by isoproterenol) were always below 35 mv (mean ± se = 25 ± 0.6 mv). Similarly, potentials from normal parotid gland (in which granular tubules do not appear) never exceeded 34 mv (mean ± se = 20 ± 2.4). In submaxillary, stimulation, at least over relatively long durtion, produced no change in average potential. It was concluded that membrane potentials from rat salivary glands are generally below the potassium equilibrium potential, with acinar cells showing lower values than cells of granular tubules.
Left ventricular performance and blood catecholamine levels in the isolated heart
Authors: Monroe R. Grier , La Farge C. G. , Gamble W. J. , Hammond R. P. , Gamboa R.
Published: December 2017

Left ventricular performance in the isolated heart of the dog as expressed by the peak systolic intraventricular pressure was observed during control periods when the heart was perfused with blood from a healthy anesthetized donor and after the donor was removed and the heart perfused with blood oxygenated by isolated lungs. Heart rate, coronary perfusion pressure, ventricular end-diastolic pressure, and stroke volume were maintained constant throughout. While the heart was perfused with blood from a donor, ventricular performance showed no tendency to decline, although coronary flow invariably increased. On removing the donor and perfusing the heart with blood oxygenated by isolated lungs, myocardial performance declined in proportion to the decline in the total catecholamine concentration of the perfusing blood. Restoration of catecholamine levels by infusing epinephrine and norepinephrine also restored left ventricular performance.
Light synchronization of deep-body temperature rhythms in Macaca nemestrina
Authors: Hoffman Rudolf A. , George George P. , Barrows William F.
Published: December 2017

The efficiency of low levels of illumination as biorhythm synchronizers in the subhuman primate ( Macaca nemestrina) was investigated. It was demonstrated that a day illumination level of approximately 6 ft-c alternating with approximately 0.06 ft-c night illumination served as an effective rhythm synchronizer.
Pyruvate metabolism in mammalian liver
Authors: Parli et al. C. J.
Published: December 2017

Page 1525: C. J. Parli et al., "Pyruvate metabolism in mammalian liver." Page 1532: the journal reference in item 43 should read J. Biol. Chem. 238: 17–20, 1963.
Release from alveolar macrophages of an inhibitor of phagocytosis
Authors: Ulrich F. , Zilversmit D. B.
Published: December 2017

Page 1118: F. Ulrich and D. B. Zilversmit. "Release from alveolar macrophages of an inhibitor of phagocytosis." Page 1124, column 2, line 10 of footnote 2: "85 C" should read "80 C."
Molecular regulation of digestion: short term and bond specific
Authors: Rothman S. S.
Published: December 2017

Page 77: S. S. Rothman. Molecular regulation of digestion: short term and bond specific. Page 81: in Table 1, the last line of the column under the headings "Output" and "Tg" should read "8.3 ± 1.6."
Vascular and adrenocortical responses to a specific antagonist of angiotensin II
Authors: Bravo EL , Khosla MC , Bumpus FM
Published: December 2017

Angiotensin II receptors in vascular smooth muscle and adrenal cortex have been characterized in the dog. The evidence was derived chiefly from experiments that assessed the ability of a structural analog of angiotensin II, [Sar1, Ile8] AII, to antagonize the effects of exogenously administered angiotensin II on arterial pressure and aldosterone secretion. [Sar1, Ile8] AII is a potent and specific blocker of the pressor response to angiotensinII; in the adrenal cortex, it is a much less effective inhibitor of aldosterone biosynthesis. These results indicate differences in the receptor sites for angiotensin II in vascular smooth muscle and adrenal cortex. Further, they raise the possibility that angiotensin II stimulates aldosterone secretion by mechanisms other than have already been proposed.
Effect of angiotensin II on renal water excretion
Authors: Cadnapaphornchai P , Boykin J , Harbottle JA , McDonald KM , Schrier RW
Published: December 2017

In the present study the effect of angiotensin II (AII) on renal water excretion was evaluated. In dogs undergoing a water diuresis, neither the intravenous (IV) (40ng/kg per min) nor intracarotid (5-10 ng/kg per min) infusion of AII significantly altered urinary osmolality (Uosm) or free-water clearance (CH2O). Intravenous infusion of a competitive inhibitor of AII (1-sarcosine,8-glycine AII) into hydropenic dogs also failed to alter Uosm and CH2O significantly. To examine whether AII might suppress, rather than stimulate, vasopressin release, AII was also infused into hydropenic animals. No effect on Uosm and CH2O was observed during the intracarotid infusion. A significant fall in Uosm and rise in CH2O occurred during the intravenous AII infusion, but reversal after cessation of the infusion was incomplete and statistically not significant. Some suppression of antidiuretic hormone (ADH) release during the intravenous infusion of AII, however, was suggested since no similar alteration in renal water excretion was observed during an intravenous AII infusion in hypophysectomized animals receiving a constant infusion of ADH. Taken together, the present results provide no evidence for a direct effect of AII to alter ADH release or to interfere with the peripheral action of ADH. Suppression of ADH release may sometimes occur with pressor doses of intravenous angiotensin, but this effect is clearly less consistent than previously observed with intravenous norepinephrine.
Ion transport by rabbit jejunum in vivo
Authors: Fromm D , Dibala RP , Sullivan HW
Published: December 2017

Net ion and H2O transport by jejunum adjacent to the ligament of Treitz (proximal jejunum) and midjejunum were measured in vivo by continuous perfusion with HCO3-Ringer solution containing a volume marker. Proximal jejunum secreted Na and H2O, whereas midjejunum absorbed Na and H2O. Both segments secreted CO2 and absorbed K and Cl. D-glucose stimulated absorption of Na and H2O and the transmural electrical potential difference (PD) in both segments, but these changes were not accompanied by alterations in Cl, CO2, or K fluxes. However, the increse in Na absorption caused by 3-O-methylglucose was matched by an increase in Cl absorption. This, in addition to increased tissue lactate concentration after addition of D-glucose, suggests that organic anion maintains electroneutrality for Na transport enhanced by D-glucose. Cholera toxin had no effect on ion transport or PD in proximal jejunum, but cholera toxin stimulated secretion and increased the PD in more distal jejunum. Although proximal jejunum shows spontaneous secretory activity, its capacity for secretion is not as great as more distal small intestine.
Right atrium and renal sodium excretion
Authors: Stitzer SO , Malvin RL
Published: December 2017

Inflation of a balloon in the right atrium of 13 dogs resulted in salt and water retention not attributable to changes in GFR, RPF, filtration fraction, mean arterial pressure, left atrial pressure, or renal venous pressure. The response to right atrial balloon inflation was compared with the renal effects of constriction of the abdominal aorta above the renal arteries and constriction of the ascending aorta. Neither procedure evoked the same response as balloon inflation. Results suggest that the decrease in mean arterial pressure which accompanies balloon inflation accounts for only part of the decreased salt and water excretion. There was no significant difference between the responses of denervated and intact kidneys to right atrial balloon inflation. A binary response to stretching of the right atrium is suggested, both components apparently involving hormonal mediation.
Interaction of aortic and carotid sinus baroreceptors: effect of activation times
Authors: Katona PG , Tan KS
Published: December 2017

Changes in pulse-wave velocity were simulated by changing the relative timing between aortic and carotid sinus barorecptor activity in anesthetized rabbits and dogs. In the rabbit, electrical stimulation was used to vary the timing; in the dog, it was also varied by perfusing the carotid sinuses with externally generated pressure pulses that could be triggered in any portion of the cardiac cycle. Changing the relative delay between aortic and carotid sinsus nerve stimulation did not result in variations of blood pressure or heart rate in the rabbit. Varing the time of electrical stimulation of the carotid sinus nerve caused at most 5 mmHg change of blood pressure in the dog. Delay-related heart-rate changes could be usually observed only when the stimulus consisted of short, high-intensity bursts. When the carotid sinus was externally perfused with pulses of pressure, only one out of five dogs showed delay-related variations in blood pressure (3mmHg) and heart rate (6 beats/min). It is concluded that variations in pulse-wave velocity are unlikely to play a significant role in acute cardiovascular control.