bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiac function after embolization of coronaries with microspheres
Authors: Stone Hubert L. , Bishop Vernon S. , Guyton Arthur C.
Published: December 2017

Radioactive microspheres were injected into the coronary systems of 11 dogs, and the quantity of microspheres entering and remaining in the coronary system was determined by radioactive counting techniques. After progressive injection of small quantities of microspheres over a period of 2–3 hr, leading finally to death by cardiac failure, the total volume of microspheres remaining in the coronary system averaged only 6.5 mm3. The pumping ability of the heart at different degrees of embolization was measured by determining successive cardiac function curves, both cardiac output curves and left ventricular minute work curves. In each experiment, both the maximum cardiac output and maximum minute work output decreased approximately proportionately after each individual injection of incremental quantities of microspheres, illustrating that the functional ability of the heart can be expressed very well by the maximum level of these function curves. In all experiments, the cardiac function curves began to deteriorate spontaneously after injection of a very critical quantity of microspheres, and a vicious cycle of deterioration occurred thereafter, resulting in rapid demise of the animal.
Cr51-labeled red cell, I131-fibrinogen, and T-1824 dilution spaces
Authors: Baker Carleton H.
Published: December 2017

The differences in dilution spaces of Cr51-labeled red cells, I131-labeled dog fibrinogen, and T-1824 were studied. All three indicators were injected simultaneously into anesthetized, acutely splenectomized dogs. Arterial samples were taken at 10, 20, 30, 50, and 70 min postinjection. Another injection of the indicators was made, samples were taken, and a third injection was made. Cr51 and I131 were separated in the samples by determining the counts per minute on the day of the experiment and again 10 days later, then solving equations utilizing the concepts of differential decay. The Cr51-labeled red cell space averaged 63.9 ml/kg and was the most reliably reproduced. The average BVfibrinogen (67.9 ml/kg) was significantly less than the average BVT-1824 (73.8 ml/kg). BVfibrinogen is more reliably reproduced than BVT-1824 but less so than BVcells. The T-1824 space apparently includes more of the extravascular space than does the fibrinogen space and indicates that the volume of "extra plasma" is considerably less than previously believed.
Effect of ouabain on coronary flow, performance of heart and its oxidative metabolism
Authors: Göksel F. , Katz L. N. , Feinberg H.
Published: December 2017

Isovolumic and coronary flow preparations were used to test the action of ouabain on the heart and its coronary vascular bed. The former preparation has a left ventricle contracting isovolumically against a balloon in its cavity. In the coronary flow preparation, the input to the left heart is maintained constant with the right heart contracting hypodynamically. Ouabain in the isovolumic preparation produced an increased coronary flow, an augmentation in the magnitude of the left ventricular contraction and cardiac oxygen consumption, and a diminution of oxygen extraction. Apparently ouabain acts here primarily as a coronary dilator and the other changes appear to be secondary. This suggests that ouabain may exert its beneficial effects by lessening the deficiency in coronary flow. Ouabain in the coronary flow preparation also increases coronary flow but by more complex actions. In this preparation, at varying dosage levels, ouabain effects resemble the diphasic action on oxidative metabolism seen in heart muscle slices.
Relation between venous pressure and blood volume in the intestine
Authors: Johnson Paul C. , Hanson Kenneth M.
Published: December 2017

The pressure volume characteristics of the intestinal venous vasculature were studied in vivo by a weight technique. The pressure-volume relationship was linear over the range 0–20 mm Hg. In a few experiments the volume increment appeared to be reduced at venous pressures above 30 mm Hg. The average compliance of the intestinal veins was 0.34 ml/mm Hg 100 g tissue. The time course of the blood volume change was also examined. Rapid elevation of venous pressure to a higher level caused blood volume to increase at an exponentially declining rate. Therefore, the phenomenon of creep in the intestinal veins appears to be a simple exponential process. The half time of the increase in venous volume averaged 7.5 sec while the time constant was 10.9 sec. The magnitude of the time constant suggests the presence of elements of rather high viscosity in the venous wall.
Influence of some factors on oxygen uptake of canine cardiac Purkinje fibers
Authors: Greenspan Kalman , Cranefield Paul F.
Published: December 2017

The rate of oxygen uptake of quiescent Purkinje fibers of the dog's heart was determined using a flow respirometer and oxygen polarography. At ambient oxygen concentrations of 60% or higher the rate of uptake was 0.739 mm3/mg wet weight per hr at 35 C. The temperature coefficient over the range 25–35° was 2.3. The uptake was independent of the ambient oxygen concentration at oxygen concentrations equal to or greater than 60% of an atmosphere. In lower oxygen concentrations the rate of uptake was found to be depressed. The depression of uptake in the lower oxygen tensions is probably the result of diffusion limitation; it may, however, reflect dependence of resting uptake on oxygen concentration.
Intracellular distribution of cations and protein in regenerating rat liver
Authors: Uyeki Edwin M.
Published: December 2017

The intracellular distribution of several cell constituents was studied at different periods after partial hepatectomy in the rat. The temporal pattern of cation and protein distribution can be divided into two phases: there is an initial phase in the first 24 hr posthepatectomy in which sodium and water increased in tissues concomitant with a decrease in potassium and protein. The levels of these several constituents subsequently approached values that were higher than in the control at 1 and 2 days posthepatectomy and were generally maintained at these values throughout the assay period. The reasons for the accumulation of higher than normal levels of both potassium and sodium are as yet uninterpreted; the higher than control potassium-to-sodium ratios generally observed in the intracellular compartments are due to the relative greater accumulation of potassium ions over sodium ions during this period. Comparing the intracellular compartments, the greatest alterations of constituents in the early phases of liver regeneration were observed in the soluble portion.
Effect of serotonin on cardiac output and organ blood flow of rats
Authors: Takács L. , Vajda V.
Published: December 2017

The effects of intraperitoneal and intravenous administration of serotonin on cardiac output, blood pressure, and organ distribution of blood flow (Rb86) were studied in the rat. Fifteen to thirty minutes after intraperitoneal injection (10 mg/kg) cardiac output was unchanged, while blood pressure was significantly reduced. Increase in blood flow was noted in the myocardium, pulmonary parenchyma and "carcass" (skeletal muscle, bone, CNS), with decrease in the kidney and the skin. Splanchnic blood flow was unchanged. Conversely, intravenous infusion of serotonin produced an increase of cardiac output, blood pressure, and cutaneous blood flow.
Single proximal tubules of Necturus kidney. VI: Nature of potassium transport
Authors: Oken Donald E. , Solomon A. K.
Published: December 2017

K concentration and apparent unidirectional K fluxes have been measured in Necturus kidney proximal tubule. Mean tubular K in 12 collections from the most distal segment of the tubule is 5.4 ± 0.3 mm, and the tubular K to serum K ratio in these experiments is 1.6 ± 0.1, not significantly different from the inulin concentration ratio, 1.4 ± 0.2. The glomerular fluid to serum K concentration ratio is 1.01 ± 0.03. Apparent unidirectional K fluxes were measured using stopped-flow microperfusion technique in 11 experiments with perfusion fluid containing about 7 mm K. The apparent mean K influx was 52 ± 6 pmoles/cm2 sec and the apparent efflux was 49 ± 3 pmoles/ cm2 sec.
Erythropoiesis and red cell survival in the hypothyroid dog
Authors: Cline Martin J. , Berlin Nathaniel I.
Published: December 2017

Determinations of blood volume, total red cell volume, plasma and red cell iron turnover rates, and red cell survival were performed in seven dogs prior to and subsequent to radioiodine destruction of the thyroid gland. Anemia developed slowly in all animals as a result of a diminished rate of red cell synthesis. Erythrocyte survival was unaffected by thyroid ablation. Serum iron concentration decreased in five animals despite the apparent adequacy of dietary iron intake and the absence of detectable external loss. In two animals, parenteral administration of iron failed to correct the anemia. Vitamin B12 was ineffective in correcting the anemia or in producing a reticulocyte response in two other animals.
Effect of changes in carotid sinus pulse pressure on catecholamine blood levels
Authors: Nakano Jiro , Schryver Christian De
Published: December 2017

A study was made on the effect of changes in arterial pulse pressure per se on catecholamine secretion in the anesthetized dog. "Elasticity" bottles were inserted bilaterally in the common carotid arteries in order to change the magnitude of the pulse pressure in the carotid sinus areas without changing the mean arterial blood pressure. It was observed that a marked decrease in the pulse pressure resulted in significant increases in heart rate ( P < 0.005) and catecholamine plasma levels ( P < 0.005). The mechanism and role of this increase in plasma levels of catecholamines are discussed.
Effect of parasympathetic stimulants on Ca45 transfer in vitro in rat parotid glands
Authors: Dreisbach Robert H.
Published: December 2017

The effect of parasympathetic stimulants on the uptake and loss of Ca45 by rat parotid glands in vitro has been studied. Acetylcholine increased rate of entry of Ca45 during a 10-min exposure, as shown by increase in the residual radioactivity remaining in glands after washing for 1 hr in nonradioactive media containing atropine. Both pilocarpine and acetylcholine increased the rate of loss of Ca45 from rat parotid glands when glands previously exposed to Ca45-containing media were repeatedly transferred to Ca45-free media.
Urinary osmolality as a function of flow rates in several diuretic states
Authors: Herms Wolfgang , Abbrecht Peter H. , Alzamora Fernando , Malvin Richard L.
Published: December 2017

The effect of different solute loads on the renal concentrating mechanism was evaluated at different glomerular filtration rates (GFR). GFR was varied by partial ureteral or arterial occlusion in dogs undergoing osmotic diuresis. A Ringer's solution was infused to which the following solutes were added so that the final concentrations of the solutes were as follows: a) 383 mm/liter mannitol + 255–285 mm/liter NaCl; b) 500 mm/liter urea; c) 193 mm/liter mannitol; d) 300 mm/liter urea + 385 mm/ liter mannitol. Steady-state values for GFR, urine flow, and urine osmolalities were obtained for the occluded and control kidneys and expressed as the ratio occluded-to-control. Changing the sodium chloride load did not alter the correlation between flow rate and urine osmolality as found in previous experiments with dogs which were not infused with additional sodium. However, variations in the urea and mannitol load did alter this relationship. The greater the mannitol load the lower was the osmolality ratio at any given GFR. The results indicate that both urea trapping and urine flow rates are important determinants of urinary concentrating ability.
Urinary excretion of water, sodium, and total solutes by the pregnant rat
Authors: Lichton I. J.
Published: December 2017

Excretory responses were studied before mating and at intervals during gestation in conscious rats given isotonic saline solution by stomach tube and in sodium pentobarbital-anesthetized rats infused with saline intravenously. In conscious rats excretion of water and solutes in relation to the dose given was enhanced on day 13 of gestation in comparison to before mating and significantly depressed on day 20. Depressed excretion of water on day 20 was proportional to the number of newborn pups and was accompanied by equally depressed excretion of sodium and total solutes. In anesthetized rats excretion of water, sodium, and total solutes was also significantly depressed on day 20 of gestation while glomerular filtration rate was only slightly depressed. Tubular reabsorption of water and solutes was significantly higher in 20-day pregnant rats than in nonpregnant rats. It is suggested that this increase in tubular reabsorption may represent a response to depletion of maternal extracellular fluids by the growing fetuses.
A linear method for determining liver sinusoidal and extravascular volumes
Authors: Goresky Carl A.
Published: December 2017

Multiple indicator dilution studies of the hepatic circulation in the dog were carried out using labeled red cells, albumin, inulin, sucrose, sodium, urea, water, and T-1824. The materials were completely recovered in the outflow. Concentrations were expressed as fractions of the injected mass. The outflow pattern of each of the substances was displaced relative to the red cell curve, showing a lower peak concentration and longer transit time. The displacement was largest for water and urea, least for albumin and T-1824, intermediate for inulin, sucrose, and sodium. The results were analyzed using a flow-limited linear two-compartment model system. The analysis yielded estimates of sinusoidal blood volume and of the extravascular volumes of distribution of the diffusible labels. Water and urea volumes agreed with the liver weights and this agreement was taken as validation of the method of analysis. Volumes calculated for the other presumably extracellular substances demonstrated that the rapidly available extracellular space diminishes with increase in the molecular weight of the substance.
Effect of dietary amino acid pattern on plasma amino acid pattern and food intake
Authors: Sanahuja Juan C. , Harper Alfred E.
Published: December 2017

Effects of a dietary imbalance of amino acids on the plasma amino acid pattern of the protein-depleted rat are described. The amino acid imbalance was created by adding a mixture of indispensable amino acids lacking histidine to a diet in which the protein was provided by 6% of beef blood fibrin. The addition of this amino acid mixture was previously shown to cause depressions in growth and food intake. In the present study the depression in food intake was preceded by a fall in plasma histidine concentration and at the same time the concentrations of some of the other indispensable amino acids, especially threonine, began to rise. The ratios of several indispensable amino acids to histidine in the plasma were elevated when food intake was most severely depressed.
Effect of insulin on release of glucose and urea by isolated rat liver
Authors: Mortimore Glenn E.
Published: December 2017

Direct inhibitory effects of insulin on the release of glucose and urea from isolated livers of fasted and nonfasted rats have been established by use of an improved cyclic perfusion technique in situ. In livers of fasted animals the accumulation of perfusate glucose was small and, in the virtual absence of measurable glycogen, was presumed to be derived largely from protein. Insulin added to the perfusate caused an immediate partial inhibition of both glucose and urea release in amounts suggesting reduced gluconeogenesis. In livers of normal nonfasted rats, on the other hand, the output of glucose was far greater. Although insulin suppressed urea production as in the fasted rat liver, its inhibitory effect on glucose accumulation was severalfold larger. These facts pointed to the existence of a second, and quantitatively more important, action of insulin on hepatic glucose metabolism. With respect to its rapidity of onset, magnitude, and sensitivity to insulin this action compared favorably with glucose responses to insulin in isolated extrahepatic tissues.
Heat balance and reactivity to endotoxin
Authors: Fekety F. Robert
Published: December 2017

Shorn rabbits, supine restrained rabbits, and rabbits in the cold had relatively low body temperatures because their caloric losses were greater than normal, and they did not develop fever after endotoxin, adrenaline, or endogenous pyrogen. In such animals, mechanisms of heat conservation seemed maximally operative prior to testing; the absence of fever was related to limits imposed by ambient temperature upon heat conservation by further vasoconstriction in the ear, and shivering responses were not uniformly seen. Ordinarily appropriate late mechanisms of heat dissipation were noted after endotoxin despite the lack of fever. Febrile responses became possible when shorn animals were warmed. After repeated endotoxin injection, greater vasoconstriction over the trunk was feasible, the limitations of ambient temperature upon heat conservation became less decisive, and fever resulted. The unusual circulatory and thermal responses of chilled rabbits should be taken into consideration when performing similar experiments.
Survival of newborn ground squirrels after supercooling or freezing
Authors: Popovic Pava , Popovic Vojin
Published: December 2017

Six of seven 2-day-old ground squirrels survived without any harmful consequences 11 hr supercooling to body temperatures of –3 to –4 C. Longer exposure at the same body temperature was not followed by survival. Of 12 ground squirrels which were kept at stabilized body temperatures of –6 and –8 C for 5 hr, 10 animals survived. Electrical activity of the heart was not detectable when the body temperature of ground squirrels was below –2 C. Immersion of newborn ground squirrels in –35 C alcohol-dry-ice mixture caused their bodies to freeze after 15–20 sec, suddenly turning white and rigid. Ground squirrels survived the freezing which lasted less than 2 min. At the end of 2 min immersion the esophageal temperature of cooled animals was –10 to –15 C.
Prepartum to postpartum uterine and abdominal contractions in cows
Authors: Gillette D. Dale , Holm Louis
Published: December 2017

Uterine and abdominal contractions were studied in cows near and during calving by means of microballoons imbedded in the uterine mucosa, connected to external strain gauges and recorded electronically. Uterine "activity" is defined as a function of intensity and time. "Abdominal units" are defined as a function of intensity. A transition period was found in which irregular, brief, non-coordinated contractions of the prepartum period were transformed into regular, long, coordinated, propagated contractions of parturition. Uterine contractions did 90% of the work of parturition and were directly, but not linearly, proportional to fetal "resistance." Abdominal efforts were intense, brief, and not related to fetal size. Uterine peristalsis is proposed as initiated by the circular muscle contractions and composed of sequential contractions of adjacent circular muscle ring segments synchronized by propagation of the action impulse through the longitudinal muscles. Evidence was found of a local progesterone effect.
Influence of promethazine on circulatory response to endotoxin in dogs
Authors: Anderson Fred L. , Kuida Hiroshi , Hecht Hans H.
Published: December 2017

Histamine has been implicated as an intermediary in the mechanism of experimental endotoxin shock. The effect of pretreatment with an antihistaminic drug, promethazine hydrochloride (PMZ), on the hemodynamic response to E. coli endotoxin was studied in a group of 13 anesthetized dogs. Results were compared with the characteristic effects of endotoxin obtained in six control animals. Parameters that were measured and evaluated for possible effects of pretreatment were as follows: systemic artery, pulmonary artery, and portal vein pressures; cardiac output; heart rate; and calculated systemic and pulmonary resistances. In six animals that received doses of PMZ ranging from 1 to 9 mg/kg, the responses to endotoxin were not significantly different from those in the control group. However, in a group of seven dogs pretreated with a standard dose of 20 mg/kg PMZ, a modified response was demonstrated consisting of significant reduction in the magnitude of early systemic hypotension and portal venous hypertension. Pulmonary hypertension was augmented. The results are consistent with the interpretation that certain circulatory effects of endotoxin are mediated through histamine and that these are partially amenable to selective inhibition by an adequate dose of an antihistaminic agent such as PMZ.
Effect of sympathomimetic amines on intramyocardial pressure in the rabbit
Authors: D'Silva J. L. , Mendel D. , Winterton M. C.
Published: December 2017

Intramyocardial pressure has been measured in rabbits by means of a small inflatable latex balloon inserted into the myocardium of the left ventricle. The mean maximum intramyocardial pressure was found to be of the order of the aortic diastolic pressure. Adrenaline and isoprenaline infusion increased the maximum intramyocardial pressure; noradrenaline was without effect. Differential pressure plots of aortic and intramyocardial pressure against time showed that the increase in intramyocardial pressure produced by adrenaline and isoprenaline was matched by at least an equal increase in aortic systolic pressure. The same linear relationship was found when the total area under the curves (i.e., a function of flow) was plotted against the aortic diastolic pressure in controls and during infusion with sympathomimetic amines.
Hemodynamic determinants of the maximal rate of rise of left ventricular pressure
Authors: Wallace Andrew G. , Skinner N. Sheldon , Mitchell Jere H.
Published: December 2017

The maximal rate of left ventricular pressure development (max. dp/dt) was measured in an areflexic preparation which permitted independent control of stroke volume, heart rate, and aortic pressure. Max. dp/dt increased as a result of elevating ventricular end-diastolic pressure. Elevating mean aortic pressure and increasing heart rate each resulted in a higher max. dp/dt without a change in ventricular end-diastolic pressure. Aortic diastolic pressure was shown to influence max. dp/dt in the absence of changes in ventricular end-diastolic pressure or contractility. Increasing contractility increased max. dp/dt while changing the manner of ventricular activation decreased max. dp/dt. These findings demonstrate that changes in max. dp/dt can and frequently do reflect changes in myocardial contractility. These data also indicate that max. dp/dt is a complex function, subject not only to extrinsically induced changes in contractility, but also to ventricular end-diastolic pressure, aortic diastolic pressure, the manner of ventricular activation, and intrinsic adjustments of contractility.
Vasomotor responses in a resting musculocutaneous area during muscular activity
Authors: Mitchell Jere H. , Remensnyder John P. , Sarnoff Stanley J.
Published: December 2017

The vasomotor responses in a resting musculocutaneous area, when muscular contractions were electrically induced in another area, were studied in anesthetized dog preparations. The responses consist of an initial transient vasodilatation of substantial magnitude followed by a modest vasoconstriction. The initial vasodilatation was not modified by atropine sulfate but was absent during ganglionic blockade with tetraethylammonium chloride and after surgical sympathectomy. This suggests that the initial vasodilatation is due to a brief diminution in sympathetic vasoconstrictor activity and not to activation of cholinergic sympathetic vasodilator fibers. It is thought likely that the transient diminution in sympathetic vasoconstrictor activity observed in a resting muscular area also occurs simultaneously in the exercising muscular area and thus plays a role in augmenting blood flow to active muscular areas in the initial moments of the transition from rest to exercise.
Metabolism of phosphorus in the supersensitive submaxillary gland of the cat
Authors: Burford H. , Huggins C. G.
Published: December 2017

We have used the supersensitive submaxillary gland of the cat to investigate the relationship between secretory phenomena and phosphorus metabolism, in vivo. Supersensitivity was produced by surgical removal of a 1 cm section of the chorda tympani nerve or by chronic administration (15 days, s.c.) of 1, 1-diphenyl-4-N-piperidinobutyramide (Hö 9980). After subcutaneous injection of radiophosphorus, secretion was induced by administration of epinephrine or acetylcholine over a 2-hr experimental period. Analyses for phosphorus and radioactivity on the different phosphorus-containing fractions have shown that there was an increase in the specific activity of the phosphatido-peptide and phospholipid fractions obtained from the supersensitive gland. No increase was apparent in the radioactivity in the total acid-soluble or 7-min hydrolyzable fractions. The increase in metabolic activity of the phosphatido-peptide and phospholipid fractions was found to be blocked when atropine or dihydroergotamine were used to inhibit secretion. We interpret our findings as supporting evidence for the participation of these two fractions in secretion of saliva in a manner not yet understood.
Kidney oxygen availability
Authors: Hardwick D. F. , Strauss J. , Misrahy G. A.
Published: December 2017

Mean oxygen availability (aO2) was measured in the kidney cortex and bone marrow of cats by polarographic technique. O2, CO2, and Apresoline increased the mean aO2, whereas N2, Amobarbital, Pitressin, Adrenalin, Methacholine, venesection, and spinal anesthesia decreased it with varied effects on the cyclic fluctuations in mean aO2. These results suggest that the regulation of kidney aO2 is intermediate between brain and bone marrow oxygen and that kidney hypoxia is not the only factor responsible for erythropoietic stimulation.
The Bohr effect related to blood and erythrocyte pH
Authors: Hilpert Peter , Fleischmann Renate Gislinde , Kempe Doris , Bartels Heinz
Published: December 2017

The Bohr effect of the blood and the red cell hemolysates of adult and newborn humans, goats and kids, and sheep and lambs were determined and the physiological significance is discussed. Similar determinations were made on blood from an African elephant, yak, camel, Dybowski deer, and llama. The strong displacement to the right of the oxygen dissociation curve which occurs in kids and lambs during the first 5 days of life can be largely explained by a change in the pH value within the erythrocytes. When the oxygen affinity is expressed by the oxygen pressure necessary for half saturation (T50) at a constant cell pH, considerable differences exist between species.
Partial purification of intermediate coagulation product I and a study of its properties
Authors: Zucker-Franklin Dorothea , Spaet Theodore H.
Published: December 2017

Intermediate coagulation product I, a precursor of "blood thromboplastin," has been isolated and partially purified by starch-block electrophoresis. The electrophoretic procedure eliminated thrombin, fibrinolytic and esterase activity, phospholipids, and an unidentified inhibitor of product I which appears to be present in serum. Partial purification markedly increased the heat and storage stability of the compound. Product I has been shown to convert purified prothrombin to thrombin in the presence of factor V and phospholipids. Its activity is not inhibited by diisopropyl fluorophosphate. The compound is antigenic and its activity can be inhibited by specific antibody which considerably lengthens the clotting time of substrate plasma. Purified product I failed to induce viscous metamorphosis of platelets. This activity in the crude preparations was shown to result from contaminating thrombin.
Blood flow and oxygen debt repayment in exercising skeletal muscle
Authors: Coffman Jay D.
Published: December 2017

Blood flow and oxygen consumption of the hind limb of the dog were determined before and following short periods of femoral artery occlusions during rest and three levels of exercise. Flow debts were underpaid or barely repaid. Oxygen debts were entirely or partially repaid depending upon the level of muscle performance and the duration of the ischemic period. In resting muscle and during light exercise, both increased blood flow and oxygen extraction were involved in repayment of the oxygen debts while an increased blood flow was most important during medium and strong exercise. Since oxygen debts were often not repaid during strong exercise in the presence of a decreased arteriovenous oxygen difference (and often an oxygen utilization below control levels), oxygen extraction was the limiting factor. Significant excess repayments of oxygen debts occurred in resting muscle and for 30-sec ischemic periods during light and medium exercise. The similarity of these data, especially during medium and strong exercise of skeletal muscles, to the responses of the beating dog heart to ischemic periods is pointed out.
Relationship of blood flow and myocardial Rb86 clearance in right and left ventricles
Authors: Love William D. , O'Meallie Lawrence P.
Published: December 2017

The rate of myocardial clearance of Rb86 from arterial blood and the rate of coronary blood flow were studied simultaneously during a 10-min period of isotope infusion in dogs. In order to measure blood flow to the right and left ventricles separately using the Fick principle, venous blood was obtained from an anterior cardiac vein and from the coronary sinus. The relationship of myocardial blood flow and Rb86 clearance was not detectably different in the right and left ventricles. The percentage error in predicting flow from clearance rose as the values increased. At rates of flow below 6 ml/g 10 min the mean error was 4.7%. From 6 to 12 ml/g 10 min the mean error was 10.0% in controls and 14.4% in a group with pulmonary embolism or obstruction of the pulmonary artery. Since the clearance technique does not require catheterization of a cardiac vein, this method can be used to study coronary blood flow under conditions approximating the undisturbed state.
Renal water reabsorption during saline and urea osmotic diuresis in the dog
Authors: Maude David L. , Wesson Laurence G.
Published: December 2017

Free water reabsorption (Twc) was measured in conscious dogs during a long-term, reasonably steady-state osmotic diuresis induced either by sodium salts or by urea. After 4 to 8 hr the original solute was partially replaced by urea or by sodium salts. Both the replacement of sodium salts by urea and the converse procedure were associated with an augmentation in Twc. During sodium diuresis Twc always fell during the first 2 or 3 hr, a change which appeared unrelated to glomerular filtration rate (GFR) or to osmolar clearance. During the course of urea diuresis Twc steadily increased and showed a positive correlation with GFR. A possible basis for such a correlation is discussed.
Altered neuron population in L7 segment of dogs with experimental hind-limb rigidity
Authors: Gelfan S. , Tarlov I. M.
Published: December 2017

Establishment of the total neuronal population in a single spinal segment, its distribution in the spinal gray matter, cellular-caliber spectra, and motoneuron:interneuron ratio, hitherto unavailable, has made it possible to correlate quantitatively the functional disorganization in the lumbosacral cord of dogs with hind-limb rigidity, produced by temporary ischemia, with the neuronal deficit and with previously established neurophysiological alterations. There are some 375,000 neurons in the L7 segment: one-half in the dorsal horn and one-fourth each in intermediate zone and ventral horns. Small cells outnumber large ones 24:1. Some 82% of the large neurons are in the ventral horn; two-thirds of these are alpha motoneurons. Mononeurons, large and small, are outnumbered by interneurons, 7:1 in the ventral horn and 30:1 in the entire spinal gray matter. Most or all of the cells destroyed in L7 segments of three rigid dogs were interneurons. All motoneurons may survive when 80% of the interneurons are destroyed. The survival percentage was consistently higher among the neurons in the ventral horn. The higher mortality among small neurons in ventral horns was due principally to topographical deployment.
Effects of calcium removal on bullfrog gastric mucosa
Authors: Forte John G. , Nauss Alan H.
Published: December 2017

Removal of calcium from isolated bullfrog gastric mucosae by serial washings in calcium-free solutions or by the addition of EDTA or citrate caused a fall in transmucosal potential difference, a rise in the mucosal conductance, and an apparent decrease in the rate of acid secretion as measured by the pH stat method. Unless the potential difference fell to values very nearly zero the short-circuit current was not significantly decreased. Unidirectional fluxes of chloride in both directions across the mucosa were increased by EDTA, but the net flux, or actively transported chloride, was not significantly altered. This suggests that the removal of calcium by these methods does not interfere with active chloride transport. The increased movement of sodium and sucrose across the mucosa after EDTA suggests that a large part of the permeability change is occurring at the spaces between cells. Because of the large permeability changes accompanying removal of calcium it is postulated that the process of H+ production is not directly inhibited.
Relation of blood pH and CO2 to central stimulatory effects of saline on dogs
Authors: Höök Olle , Rubinstein Morton , Aird Robert B.
Published: December 2017

Normal saline (0.9% NaCl, pH 5.85) infused intracisternally in dogs has a general excitatory effect on the central nervous system, producing increased rate and depth of respiration and increased muscular tone with muscle discharges, especially from facial, cranial, and neck muscles. This excitatory effect correlated most closely with changes in systemic pCO2. being enhanced when the arterial pCO2 was decreased and being depressed when the arterial pCO2 was increased. This excitatory effect also can be depressed or abolished by relatively small concentrations of CaCl2. Mode of action is discussed.
Prothrombin homeostasis in cross-circulated normal and Dicumarol-treated dogs
Authors: Langdell R. D. , Weaver R. A. , Price R. E.
Published: December 2017

A series of experiments was done using the technique of cross circulation to study the fate of plasma prothrombin. Arteriovenous shunts of polyethylene tubing were made between normal dogs and dogs made prothrombin-deficient by administering Dicumarol. The shunts were maintained for as long as 4 hr. Prothrombin activity of the plasma of each dog was determined at intervals throughout the cross circulation and recovery period. The immediate effect of this procedure is simple dilution of the plasma prothrombin of the normal dog with the prothrombin-deficient plasma of the Dicumarol-treated animal. After cross circulation, prothrombin returns slowly to the plasma of the normal dog. These studies indicate that prothrombin is not present in extravascular sites in amounts sufficient to influence plasma prothrombin activity. Prothrombin was maintained in the plasma of the Dicumarol-treated dog only a few hours. Equilibration of plasma prothrombin with extravascular fluids does not appear to be the primary factor in this rapid loss of acquired plasma prothrombin activity.
Compensation to exsanguination hypotension in healthy conscious dogs
Authors: Rushmer Robert F. , Watson Nolan , Harding Donald , Baker Donald
Published: December 2017

In some earlier studies on exsanguination hypotension in conscious dogs, reduction in systemic arterial pressure to shock levels was accompanied by a transient tachycardia during the removal of blood, but the heart rate returned to level, at or near control values during extended periods with the mean arterial pressure between 40 and 60 mm Hg. This observation stimulated a series of experiments on five healthy conscious dogs in which transient hypotension was induced by withdrawing blood from the region of the right atrium to determine which mechanisms were dominant in the compensatory reaction. A surprising degree of variability in response was encountered, such that tachycardia was the main response on some occasions, increased peripheral resistance on others, and in still others, several mechanisms appeared to play a role. Similar variability in the response to exsanguination have been reported in human subjects. These observations suggest that the baroceptor reflexes are not simple servo controls and their role in everyday cardiovascular responses should be re-examined.
Characteristics of blood flow in branches of the renal artery
Authors: Harvey Rodney B.
Published: December 2017

A semi-isolated arterial blood-perfused dog kidney preparation was used to study autoregulation in two primary branches of the renal artery simultaneously. Autoregulative resistance changes were nearly completely limited to the specific arterial branch in which the perfusion pressure was changed. The other arterial branch inflow kept at nearly constant perfusion pressure showed very little if any change. The effects of vasoactive drugs were likewise restricted to the specific portion of the arterial bed into which they were injected. When only one branch of the renal artery was clamped off, the pressure in it fell to about 12 mm Hg indicating that there is little effective arterio-arterial cross anastomosis. Blood draining in a retrograde direction from one branch artery opened to the atmosphere was similar in composition to arterial blood in that it did not show evidence of the extraction of test substances that was occurring in the perfused portion of the kidney.
Active and passive components of pulmonary vascular response to vasoactive drugs in the dog
Authors: Feeley James W. , Lee T. David , Milnor William R.
Published: December 2017

Pulmonary blood volume was altered by intravenous infusion of selected drugs. To determine whether these alterations were the result of active changes in pulmonary vascular distensibility or were simply passive, simultaneous hemodynamic measurements were made, including pulmonary blood flow, vascular resistance, and pressures in pulmonary artery, left atrium, small pulmonary veins, and pleural space. In most instances it was necessary to postulate a mixture of active and passive events to account for the results. Epinephrine and norepinephrine elevated left atrial pressure and thus led to passive distention of the pulmonary bed (mean pulmonary blood volume increment, closed chest: epinephrine + 2.6 ml/kg, or 24%; norepinephrine + 2.7 ml/kg, or 25%), in spite of the stiffening and vasoconstrictive effects previously demonstrated in the isolated lung. Isoproterenol increased the volume (+3.4 ml/kg, 31%) and lowered the resistance of the bed by increasing its distensibility, effects sometimes re-enforced by a rise in pressure secondary to increased output. Histamine produced active pulmonary venoconstriction, with passive distention upstream, so that net changes in volume and resistance were variable.
Influence of thymectomy on growth of secondary reproductive structures in rats
Authors: Martin Constance R.
Published: December 2017

Ventral prostate glands and seminal vesicles of Long-Evans rats, thymectomized at 6–6 1/2 weeks of age and autopsied 3 weeks later, were significantly heavier than those of sham-operated rats. Values for thymectomized rats were as great as or greater than those for unoperated controls. The influence of thymectomy and sham operation was less pronounced when surgery was performed on rats which had not yet entered or had completed the most rapid phase of sexual development. A possible role of the thymus gland in the response to stress is discussed.
Relation between hydrogen ion secretion and oxygen uptake by gastric mucosa
Authors: Forte J. G. , Davies R. E.
Published: December 2017

Bullfrog gastric mucosae were isolated, mounted between two glass chambers, and bathed with physiological salt solutions equilibrated with 5% CO2 and 95% O2. Oxygen consumption (qO2; measured polarographically) and acid secretion (qH+; pH stat method) were measured along with the transmucosal potential difference (p.d.) and current passing through the mucosa. Histamine (4 x 10–4 m) caused an increase in qH+ and qO2. In measurements on nine short-circuited mucosae the mean ratio for the ΔqH+/ΔqO2 was 2.1. Sodium thiocyanate (0.5–15 mm) caused a decrease in qH+ and qO2 and an increase in short-circuit current. These effects were reversible. The ratio of ΔqH+/ΔqO2 induced by thiocyanate varied from 5.0 to 12.0. Current (0.5 to 1.0 ma/cm2) passed through the mucosae, which reversed the normally observed p.d. to values between +70 and +240 mv (secretory side with respect to nutrient side in an external circuit), caused a decrease in qH+ and qO2; the average ΔqH+/ΔqO2 was approximately 13. Using either thiocyanate or electric current the ratio of the induced ΔqH+/ΔqO2 can really exceed 4.0, the electrochemical equivalent of oxygen, and thus if this extra oxygen provides the energy for the extra acid secretion these results invalidate a simple redox pump hypothesis of hydrogen ion transport by gastric mucosa.
Role of bile and pancreatic juice in cholesterol absorption and esterification
Authors: Borja C. R. , Vahouny George V. , Treadwell C. R.
Published: December 2017

Absence of bile and pancreatic juice in the intestinal tract totally abolished absorption of cholesterol-4-C14 into thoracic duct lymph. Similarly, intestinal cholesterol esterase activity approached zero in animals lacking both bile and pancreatic juice. Intestinal cholesterol esterase could still be demonstrated in animals deprived of pancreatic juice, but which received an infusion or intragastric administration of bile salts. Absorption of cholesterol was shown to occur even in the complete absence of pancreatic juice, provided bile salts were present in the intestinal tract. Some synthesis of cholesterol esterase by the intestinal or reactivation of residual cholesterol esterase in the presence of bile salts is postulated. Thus, pancreatic secretion is not absolutely required for cholesterol absorption, although it has a stimulating effect in the presence of bile salts. This effect is attributed to its cholesterol esterase content. In the presence of bile salts, the process of esterification is postulated to be a rate-limiting step during intestinal absorption of dietary cholesterol.
Thirst motivation associated with the salt arousal of drinking
Authors: Wayner M. J. , Ross J. A. , Prien R. F.
Published: December 2017

Results represent two additional tests of the thirst deprivation trace hypothesis based upon more complex tasks. Tests are based upon the fact that thirst induced by a moderate dose of hypertonic saline (3.0 mEq of a 15% NaCl solution) injected subcutaneously develops rapidly, remains constant for a relatively long period of time (6–7 hr), and provides an opportunity to measure its facilitation (drive) on performance as a function of time independent of differences in consummatory activity. Data of the first experiment support the hypothesis and demonstrate that the facilitation of a previously learned response to depress a lever and obtain water when thirsty will increase as a function of time following the injection. In the second experiment on maze learning the effect did not appear in either measure, running time, or errors. These results indicate that the facilitatory effect is not a general one for complex measures of behavior but is specific to relatively simple motor responses and represents a motor facilitation component in drive.
Properties of mitochondria isolated from herring gull salt gland
Authors: Chance Britton , Lee Chuan-Pu , Oshino Reiko , Van Rossum George D. V.
Published: December 2017

Mitochondria have been extracted from the salt gland of the herring gull ( Larus argentatus) and were found to have normal relative amounts of cytochromes a3, a, b, c, flavoprotein, and DPNH. The mitochondria exhibit respiratory control, energy-linked DPN reduction, and other properties in common with avian heart mitochondria. The amount of mitochondrial cytochrome c in the intact gland is estimated spectrophotometrically and found to be extremely high—43 µmoles/kg wet wt. The ADP utilization per cytochrome c per second at 37 C is 19. The efficiency of sodium transport is calculated to be 34/O2 molecule or 8/ATP. This value is consistent with the thermodynamic limitations. Various possible mechanisms for sodium transport are considered in the light of these results.
Carotid chemoreceptor reflex effects on coronary flow and heart rate
Authors: Hashimoto K. , Igarashi S. , Uei I. , Kumakura S.
Published: December 2017

The innervated Langendorff's dog heart preparation in ventricular fibrillation with completely separated cross circulations to the head and heart was used for clarifying the mechanism of the carotid chemoreceptor reflex induced by nicotine, lobeline, 5-hydroxytryptamine, and acetylcholine. The effects of carotid chemoreflex were studied on the atrial rhythm and the coronary blood flow at constant pressure. A prompt decrease in atrial rate followed by a delayed acceleration was observed. Coronary dilation followed by constriction was observed concomitantly. In the atropinized heart evidences of a sympathetic component in the chemoreceptor reflex became evident. The sympathetic activity disappeared upon cooling of the head perfusion to 31 C, while the vagal action persisted. Warming to 40 C made the sympathetic effect more prominent. The reciprocal relation between the atrial rate and the coronary vascular tone may indicate a vagal coronary dilator and a sympathetic coronary constrictor effect in the dog.
Net transtubular movement of water and urea in saline diuresis
Authors: Lassiter William E. , Mylle Margaret , Gottschalk Carl W.
Published: December 2017

Anesthetized rats were given urea-C14 intravenously and infused with 5% NaCl solution containing inulin-methoxy-H3. Fluid was collected by micropuncture from surface tubules for simultaneous determination of H3 and C14 activities and osmolality. Inulin clearances, plasma and urine sodium, urine volume, and urea excretion were all greatly increased, but fractional water and urea reabsorption in the proximal convolution was similar to that in nondiuretic rats. Inulin fluid/plasma ratios in hypotonic early distal samples were slightly lower than those observed in nondiuretic rats. Urea/inulin ratios in distal samples and in ureteral urine were similar to the late proximal convolution, indicating little or no addition of urea in the loop of Henle or loss from distal convolution or collecting ducts, in contrast to nondiuretic rats. These results suggest that in the proximal convolution sodium (and therefore water) reabsorption is proportional to the rate of delivery of sodium to the tubule. Furthermore, the absence of demonstrable net transtubular movement of urea beyond the proximal convolution under conditions in which concentration gradients are reduced is consistent with the hypothesis that urea movement is largely passive.
Regulation of oxygen consumption in rat liver slices
Authors: Kayne Herbert L. , Taylor Natsu , Alpert Norman R.
Published: December 2017

Oxygen consumption, ATP, ADP, and reduced and oxidized pyridine nucleotide were measured in liver slices which were taken from fed, fasted, and refed rats and subjected to varying durations of anoxia. Oxygen consumption was low in slices from fasted rats and was increased after anoxia in all three groups of rats. Liver slices from fasted rats were also characterized by low concentrations of adenine nucleotides and oxidized pyridine nucleotide. These decreased during anoxia in all groups. Reduced pyridine nucleotide was low in fasted rats, intermediate in fed, and high in refed rats. There was an increase in concentration after 5 min of anoxia. The relationship among these variables is discussed in regard to the concept of nucleotide control of oxygen consumption.