bluuebunny/crossref_metadata_2025 huggingface dataset:
Canine atherogenesis following I131 administration and cholesterol feeding
Authors: Gonzalez I. E. , Norcia L. N. , Shetlar M. R. , Robinson C. W. , Conrad L. L. , Furman R. H.
Published: December 2017

Atherogenesis in I131-treated cholesterol-fed dogs was evaluated utilizing tissue lipid and polysaccharide, serum lipid and lipoprotein analyses. Coronary artery lesions antedated aortic lesions and both were characterized first by ground substance change without lipid accumulation. Lipids other than cholesterol then appeared, associated with varying degrees of cellular proliferation, subintimal hemorrhage and involvement of vasa vasorum and media. Marked cholesterol but not phospholipid accumulation characterized late lesions. Metachromasia was noteworthy only in fibrotic lesions. Aortic tissue hexose and hexosamine values usually were normal. Liver analyses revealed increased glycogen, especially in animals with marked reduction in high density serum lipoproteins. These animals also had highest concentrations of serum cholesterol, lipid P and lower density lipoproteins, and the most severe atheromata. Serum C/P ratios increased with increasing cholesterol levels. At serum cholesterol levels above 1000 mg %, the increments in C/P ratios were relatively smaller. Hypercholesterolemia in excess of 450 mg % for 1 year appears requisite to atherogenesis in the I131-treated cholesterol-fed dog, while comparable hypercholesterolemia in I131-treated dogs not fed cholesterol does not lead to atheroma formation.
Mechanism of cardiac damage in anoxia
Authors: DeHaan Robert L. , Field John
Published: December 2017

The following hypothesis is suggested to explain the mechanism of anoxic damage in cardiac tissue. Lactic acid accumulation, resulting from anoxia, overcomes the buffer capacity of the sarcoplasm. The consequent increased intracellular acidity leads to activation of proteolytic enzymes in the heart tissue and thus to destruction of apoenzyme protein and disruption of metabolic systems. To test this hypothesis and gain information concerning the well-known resistance of infant tissue to anoxia, adult and infant rat heart muscle was subjected to determinations of lactic acid production in anoxia, buffer capacity and proteolytic activity. Results show that a cathepsin is present in heart tissue which is active only at pH levels below 5 and is almost twice as active in adult heart as in infant. Lactic acid accumulates in both infant and adult anoxic heart, but more rapidly in the latter, and in both is accompanied by intracellular proteolysis. It is suggested that these findings are in consonance with the hypothesis, although certain discrepancies from the predicted results are noted.
Citric acid production by resorbing bone in tissue culture
Authors: Kenny Alexander D. , Draskóczy Paul R. , Goldhaber Paul
Published: December 2017

The media from resorbing mouse calvaria in tissue culture were analyzed for citric acid, calcium, phosphorus, lactic acid, protein, sodium, glucosamine and mucoprotein "tyrosine." Paralleling the resorption of bone seen morphologically, increases in citric acid, calcium and phosphorus were observed. With the exception of lactic acid no changes in other constituents were noted. The cumulative increase in citric acid was 8–19 times greater than the total citric acid content of the original calvaria. It is concluded that the resorbing bone is capable of producing citric acid metabolically, a concept which has until now lacked direct evidence.
Relationship between acetylcholine tonus in isolated rabbit intestine
Authors: Tidball M. E.
Published: December 2017

Acetylcholine content of bath fluid surrounding isolated rabbit intestinal strips was determined using the guinea pig ileum bioassay. In the 22 experiments performed, acetylcholine concentration of the rabbit bath was found to be directly proportional to the tonus manifested by the spontaneously contracting rabbit intestine at the time of assay. This relationship between tonus and acetylcholine content is statistically significant at the 99.5% confidence level. After the guinea pig ileum was atropinized it no longer responded to the rabbit bath fluid which had previously been shown to be stimulatory. It is concluded that the consistent and simple relationship between acetylcholine concentration and intestinal tonus indicates that acetylcholine is the principal factor in determining the tonus of isolated intestinal segments.
Acute effect of ACTH, aldosterone, sodium and potassium on parotid secretion
Authors: Langley L. L. , Beall W. A. , Smith J. A.
Published: December 2017

The intravenous administration of 20 u of ACTH in a single injection alters the flow and composition of parotid saliva in the dog. The flow was increased 44%, sodium concentration 75% and the potassium concentration decreased 19%. These alterations do not occur in the adrenalectomized dog. Aldosterone increased the sodium concentration only 20%, decreased the potassium level 6.3% and had an insignificant influence on flow. The intravenous infusion of sodium decreases parotid flow whereas potassium increases it. It is concluded that these alterations represent a direct influence of the electrolytes on the gland since adrenalectomy has no influence on this response. It is suggested that parotid function is changed by the infusion of these electrolytes due to the alteration of the intra-extracellular gradients. The adrenal steroids may have a similar effect.
Renal excretion of nitrofurantoin (Furadantin)
Authors: Paul Mary F. , Bender Raymond C. , Nohle Esther G.
Published: December 2017

Renal clearance of nitrofurantoin at various plasma levels was determined in the white rat. The clearance ratios (nitrofurantoin/inulin) exhibited a curvilinear relationship with the plasma level of the drug. The excretion of nitrofurantoin was found to be dependent upon the three following factors: glomerular filtration, tubular secretion and tubular reabsorption. The clearance of nitrofurantoin was not affected by urine flow nor by concurrent PAH administration. It was increased by acetazolamide and decreased slightly by probenecid. Thirty to forty per cent of the dose was recovered in the urine of rats or dogs after either per oral or intravenous administration. Rapid distribution of the drug was indicated by low plasma concentrations following intravenous administration.
Effects of epinephrine and norepinephrine on blood pressure of totally perfused dogs
Authors: Kendrick J. E.
Published: December 2017

A pump, capable of maintaining a constant flow output against pressure heads up to 200 mm Hg, has been utilized to completely replace the heart in dogs. Epinephrine and norepinephrine (0.5–10.0 µg/kg) were given in over 50 totally perfused animals. Comparable doses of these agents produced blood pressure responses essentially identical both in magnitude and character. Following adrenergic blockade by Dibenzyline, the pressor response to both epinephrine and norepinephrine was greatly reduced or abolished. The response to epinephrine after adrenergic blockade was quite often a depressor response. The depressor phase never occurred in response to norepinephrine. Sympathetic ganglionic blockade potentiated the pressure responses to both epinephrine and norepinephrine to approximately the same degree.
Effects of vasodilator drugs on normal and serotonin-constricted pulmonary vessels of the dog
Authors: Rudolph Abraham M. , Kurland M. David , Auld Peter A. M. , Paul Milton H.
Published: December 2017

Previous studies of the action of vasodilator drugs on the pulmonary blood vessels have yielded inconclusive results. Studies on the effects of continuous infusion of vasodilator agents, first on normal pulmonary vessels, and then on serotonin-constricted pulmonary vessels, suggest that the response of the pulmonary vasculature is dependent on the degree of vasoconstrictor tone present. Consistent vasodilator responses to acetylcholine, histamine and adenosinetriphosphate were elicited when the pulmonary vessels were constricted by continuous infusion of serotonin. Pulmonary vasomotor responses to drugs occur in both the small pulmonary vessels and the large pulmonary veins.
Extrarenal action of adrenal glands on potassium metabolism
Authors: Santos Roberto F.
Published: December 2017

Nephrectomized dogs have been used to demonstrate a relationship between extracellular pH changes and the net transfer of potassium from intracellular to extracellular fluid Similar experiments were done on adrenalectomized dogs to investigate the extrarenal action of the adrenal glands on potassium metabolism. These experiments were divided into three groups, each comprising adrenalectomized and nonadrenalectomized dogs. After bilateral nephrectomy, group A received no sodium salt, group B received isotonic sodium chloride and group C, isotonic sodium bicarbonate. Extracellular potassium, carbon dioxide of arterial blood and serum nonprotein nitrogen values were followed. In group A a more rapid development of acidosis coincident with a faster increase in extracellular potassium and nonprotein nitrogen occurred in adrenalectomized compared to nonadrenalectomized dogs. In groups B and C there were no obvious differences between adrenalectomized and nonadrenalectomized dogs. A faster breakdown of cells, which can be avoided by sodium salts, was considered responsible for the changes in the adrenalectomized dogs of group A, rather than change in permeability of intact cell membranes to potassium. These results imply a direct influence of sodium content of the body on protein catabolism, not mediated by the kidneys or the adrenal glands.
Mitochondrial regulation of tissue respiration
Authors: Miller A. T. , Conoly D. M. , Gabriel M. , Handy M. S.
Published: December 2017

Mitochondrial and nuclear counts and homogenate and washed mitochondrial qO2 determinations were made on kidney cortex, liver and brain of albino rats. Homogenate qO2 was inversely related to mitochondrial count in the three tissues, but directly related to cellularity and to O2 uptake per mitochondrion. It is shown that the former is a spurious and the latter a real correlation. It is concluded that the characteristic differences in the qO2 of these three tissues are due largely to specific differences in the oxidative metabolism of their respective mitochondria and not to differences in the mitochondrial count per unit weight of tissue.
Effect of 3-5-3-triiodothyroproprionic acid on chlorpromazine-induced hypothermia in the rat and ground squirrel
Authors: Hoffman R. A.
Published: December 2017

This study presents evidence that the core temperature of the ground squirrel (in December) is less affected by chlorpromazine than is the temperature of the rat. Pretreatment of these species with 3-5-3'-triiodothyroproprionic acid inhibits the chlorpromazine-induced hypothermia. This is most evident in the ground squirrel. This synthetic thyroxine analog may act to protect thermoregulatory centers from chlorpromazine.
Gross body composition and total energy metabolism in normal rats
Authors: Pratt A. W. , Putney F. K.
Published: December 2017

The gross body composition of normal, male rats weighing between 150 and 300 gm was measured utilizing recognized procedures. By determining the nitrogen and calorie content of the individual nonfat and fat fractions obtained by chemical separation of the rat's dry, total carcass, a two-compartment model was established suitable for predicting from the values of milligrams nitrogen per gram and kilocalories per gram the proportions of fat and nonfat substance in the total dry carcass of any individual rat. The theoretical line of average composition which was constructed is described by the equation: mg N/gm = –29.4 Kcal/gm + 274. The study of the total energy metabolism of five growing, male rats was done over a continuous 8-day period. From the experimental data it was possible to compute the values for kilocalories and milligrams of nitrogen retained per gram of dry carcass weight gained by the living animal. The values, when plotted, were in excellent agreement with the theoretical line of average body composition. The results indicate that the theoretical model is satisfactory for estimating the composition of the dry total carcass of the sacrificed animal or the dry carcass weight gain of the living animal.
Effect of nutrition on activity and release of lipase from rat adipose tissue
Authors: Hollenberg C. H.
Published: December 2017

Surviving rat adipose tissue induced lipolysis of a coconut oil emulsion as evidenced by a rise in the nonesterified fatty acid content of the medium following incubation. When tissue from fed rats was used addition of heparin to the medium accentuated this reaction, which, once initiated under these circumstances, continued unabated after the fat tissue was withdrawn. Heparin had no effect when fat from fasted rats was used, but the heparin response was restored by addition of glucose and insulin to the medium. Homogenates of fat from fed animals had significantly more lipolytic activity than those from fasted rats. It is concluded that lipolytic activity can be released from surviving adipose tissue of fed rats under the influence of heparin. The increase in activity in the fed state suggests that the lipase of adipose tissue may be concerned with the accumulation of fat in depots possibly by influencing the incorporation of chylomicrons into adipose tissue.
Enhancement of somatotrophic hormone-induced hypertensive cardiovascular disease by stress
Authors: Hall C. E. , Hall O.
Published: December 2017

Rats sensitized to hormone action by unilateral nephrectomy and augmented NaCl intake were treated for 32 days with a highly purified growth hormone preparation; a second group was subjected to stress, induced by periodic electrical shocks; a third group received both stress and hormone treatment, and a fourth group served as untreated controls. Stress alone caused slight hypertension in a few animals, late in treatment, unaccompanied by either cardiac hypertrophy or vascular lesions. Growth hormone caused hypertension in many of the treated animals and a few of them exhibited nephrosclerosis. Hormone and stress together caused a higher incidence and greater severity of hypertension and more marked and widespread nephrosclerosis than did hormone alone, and in addition cardiac damage was superimposed.
Effect of serotonin (5-hydroxytryptamine) on the systemic and coronary vascular bed of the dog
Authors: Maxwell G. M. , Castillo C. A. , Clifford J. E. , Crumpton C. W. , Rowe G. G.
Published: December 2017

Dogs were anesthetized with morphine and Dial-urethane-Nembutal. Cardiac output (Fick) and coronary blood flow (N2O Fick) were measured before and after the mechanical infusion of 20 µg/kg/ min. of serotonin over a period of 25 minutes. The results showed an increase in heart rate, pulmonary arterial pressure and right ventricular work. Systemic blood pressure and resistance were reduced. Coronary blood flow increased by 79%, with an increase of coronary sinus oxygen content of 3.3 vol. %. Cardiac O2 consumption and CO2 production increased. Mechanical efficiency of the left ventricle fell by 3%. Serotonin appears to act as a powerful coronary vasodilator, increasing the oxygen supply to the myocardium without increasing left ventricular work.
Cardiac and cricopharyngeal sphincter thresholds in the cat
Authors: Schenk Eric A. , Frederickson Evan L.
Published: December 2017

In order to elucidate the relative importance of extrinsic and intrinsic factors in the mechanism of cardiac sphincter closure, the effect of various surgical manipulations on opening threshold of this sphincter to increased intragastric pressure was evaluated. The experimental results show that the major mechanism in cats is one of intrinsic smooth muscle contraction. The phrenoesophageal membranes appear to play a minor role in producing a passive-type crural constriction while the gastroesophageal angle was found to be of no importance in sphincter closure. Thresholds of the upper esophageal sphincter to increased intraesophageal pressure were found to be approximately twice as great as those of the cardiac sphincter to increased intragastric pressure.
Effect of ouabain on Ca45 and Cl36 exchange in isolated rabbit atria
Authors: Holland W. C. , Sekul A. A.
Published: December 2017

The effect of ouabain (1 x 10–6 m) on Ca45 and Cl36 exchange in isolated atria has been investigated. Ouabain increases Ca45 influx, but has no effect on efflux. The action on influx is enhanced by an increase of Ca and blocked by an increase of K in the medium. These findings are interpreted to mean that the systolic action of ouabain results from an increase of Ca in the membrane or myoplasm. It is suggested that the known actions of cardiac glycosides on active transport of Na and K are secondary to this action on influx. Ouabain also increased Cl36 influx, having no action Cl36 efflux. This finding suggests that ouabain may increase passive membrane permeability.
Tolerance of recently hemorrhaged rats to secondary trauma
Authors: Pareira Morton D. , Serkes Kenneth D. , Lang Stanley
Published: December 2017

The ability of rats to withstand a second hemorrhage 48 hours after the loss of one-half of the circulating volume was diminished from that of the normal control in terms of the absolute amounts which could be withdrawn. In terms of the relative amounts (ml whole blood withdrawn/100 ml total circulating blood volume) which could be withdrawn, the previously hemorrhaged rats showed a tolerance at least that of the controls. The red cell mass at this time was 67% of the control value. No difference in ability to tolerate bilateral hind leg tourniquet trauma was demonstrated between control and hemorrhaged animals at each of two different lengths of tourniquet application (3 1/2 and 4 hr.). Sleeping time determinations at two dose levels demonstrated no difference in tolerance to intraperitoneal sodium pentobarbital between normal and previously bled rats. It is postulated that decreased tolerance to trauma when occurring in association with diminished circulating volume is a function of the type of volume demand made by the trauma and the size of the specific volume compartment available.
Mechanism of splenic protection against ‘Bartonella muris’ in the parabiotic rat
Authors: Domenico Amadeo D. , Andreotti Hebe T.
Published: December 2017

Splenectomized albino rats, carriers of Bartonella muris, develop a hemolytic syndrome in about 3–4 days after operation. If the splenectomized animal is attached to a normal partner in true parabiosis, i.e. with cross circulation, the normal partner protects the other. If it is attached to a normal partner in false parabiosis, i.e. without cross circulation there is no protection. The difference in the behavior of these two types of union is associated with the different interchange of blood cells: about 0% in false and about 50% in true parabionts and not with the interchange of humors whose difference is not statistically significant. It is concluded that the splenic protection is local and not mediated through a humoral substance.
Tissue pressure and autoregulation in the dextran-perfused kidney
Authors: Hinshaw Lerner B. , Ballin Henry M. , Day Stacey B. , Carlson Curtis H.
Published: December 2017

Experiments were performed on isolated dog kidneys alternately perfused with homologous blood and dextran. Renal artery pressure, tissue pressure, perfusate flow rate and vascular volume changes were measured as arterial pressures were progressively elevated. Marked increases in overall vascular resistance RA/F occurred in all dextran- and blood-perfused kidneys throughout the autoregulatory range. Results indicate that autoregulation of flow occurs in both blood- and dextran-perfused kidneys concurrent with increases in tissue pressure. Dextran- and blood-perfused kidneys show similar degrees of autoregulation when values are expressed in terms of increase in flow per unit rise of arterial pressure and compared to preautoregulation values.
Examination of the mixing hypothesis as an explanation for elevated urinary CO2 tensions
Authors: Rector Floyd C. , Portwood Richard M. , Seldin Donald W.
Published: December 2017

To examine the adequacy of the mixing hypothesis as an explanation for high urinary CO2 tensions, urine-plasma pCO2 gradients were examined in normal subjects receiving NaHCO3 infusions in whom urinary buffer concentration was minimized by solute and water diuresis, antecedent carbohydrate diet and glucose infusions. U-P gradients varying from 23 to 78 mm Hg were generated in the face of minimal urinary buffer concentrations which varied from 1.40 to 2.95 mEq/l. Only by the most extreme assumptions, i. e. maximal heterogeneity and no back-diffusion of CO2, could the mixing hypothesis account for the observed gradients. Since these assumptions were highly improbable, it was concluded that the mixing hypothesis is not a tenable explanation of the high CO2 tension of alkaline urine.
Effect of glucagon on metabolism of glucose and acetate by isolated rat liver
Authors: Davoren P. R. , Bornstein J.
Published: December 2017

A simple method of perfusing the isolated rat liver with a small quantity of fluid is described. The technique was used to study the effect of purified glucagon on the oxidation of radioactive glucose and acetate by the liver. The changes produced by the hormone in the labeling of the C14O2 recovered from the tissue show that it promoted an increase in the utilization of unlabeled endogenous substrate by the preparation. A study of the labeling of the α-keto-glutaric and pyruvic acids contained in the perfusates has indicated that glucagon promotes an increased entry of unlabeled material into the metabolic pathway at a point after pyruvic acid and at or before α-ketoglutaric acid. It is suggested that the dilution of the radioactive C14O2 expired by the preparation was due at least in part to an increased breakdown of fats by the liver.
Effects of cardiac work on glycogen fractions of the heart
Authors: Blount Don H. , Meyer Dallas K.
Published: December 2017

Trichloroacetic acid soluble (TCA) glycogen and residual glycogen were determined in the left ventricle and interventricular septum of hearts of unfasted male albino rats. Left ventricular hypertrophy and an elevation of blood pressure were produced in rats by coarctation of the abdominal aorta for a period of 5 days. No change in concentration of either cardiac glycogen fraction was found at the end of the 5-day coarctation period. Coarctation of the abdominal aorta for 1 hour failed to alter the glycogen fractions of the left ventricle, whereas complete ligation of the aorta for the same time interval promoted the deposition of TCA glycogen. In rats subjected to 5, 15 and 60 minutes of swimming, left ventricular glycogen was significantly depleted. Residual glycogen resynthesis was complete after 1 hour of rest from 15 minutes of exercise, and the TCA fraction was significantly increased at this time. Method of sacrifice influenced the concentration of the cardiac glycogen fractions. The above experimental procedures predominantly affected the TCA fraction of cardiac glycogen.
Cardiac glycogen in hypophysectomized rats subjected to fatty acid feeding
Authors: Bowman Roger H.
Published: December 2017

Three groups of rats were deprived of regular food for an 18-hour period. Twice during the 18 hours, stomach tube feeding was employed to administer oleic acid to one of the groups and glucose to another. The third group served as a nonfed control. A fourth group was fed. Earlier reports were verified that fasting of the hypophysectomized rat results in cardiac glycogen depletion. However, the animals fed oleic acid showed an elevation in heart glycogen which was above that of both the fed controls and glucose-fed animals. These results suggest that the mechanism of action by which growth hormone exerts its cardiac glycopexic effect in the intact animal may be one of increasing the quantity of fatty acids available, with a resultant sparing of glycogen in the heart. Unlike the heart, the rectus femoris did not accumulate glycogen in the animals fed fatty acid, but rather showed values correlated with those of the liver glycogen and blood glucose.
Synthesis of proteins, lipids and nucleic acids from formate in young rats
Authors: Rappoport Donald A. , Sewell Bettie W. , Moreland Ferrin B.
Published: December 2017

Formate-C14 was injected into a 21-day pregnant rat and into 1-, 3- and 10-day-old rats. Whole fetal and 1-day-old rats and liver, heart, brain and intestine from 1-, 3- and 10-day-old rats were blended with trichloroacetic acid. The breis were fractionated into acid-soluble, protein, DNA, RNA and lipid fractions and the radioactivity of each fraction measured. Most of the activity was always in the acid-soluble fraction. Protein activity was high in all 1-day rat tissues and decreased progressively with age; it was higher 1 day after birth than before. Activity of the lipids was increased on the 1st and 3rd days and then decreased. RNA showed high activity in 1-day rats, then dropped markedly. DNA was always of low activity. It may be concluded that the rate of formation of protein, lipid and RNA from formate reflects the activity of tissues during development.
Absorption, excretion and tissue distribution of oral cyano-cobalamin in rabbits
Authors: Rosenthal Harold L.
Published: December 2017

The appearance of radioactivity in plasma, following an oral dose of Co60 cyanocobalamin, reached maximum values after 7 hours. The plasma activity during the succeeding 26-day experimental period decreased in a logarithmic fashion which was resolved into three components with biological half-lives of 29 hours, 7.1 days and 15.8 days. The 7.1-day half-life component is significantly longer than the 4-day half-life found in rabbits following intramuscular or intravenous administration of Co60 cyanocobalamin. This indicates a different, more stable, protein-cyanocobalamin complex formed during absorption. The excretion of radioactivity in urine and feces following oral dosage of Co60 cyanocobalamin demonstrates the limited absorption of cyanocobalamin from the gut of rabbits. The urinary excretion of the radioactive dose increased from 2.2% to 20.7% in animals previously injected with nonradioactive cyanocobalamin and liver tissue retained more radioactivity following nonradioactive cyanocobalamin supplementation. It is concluded that the cyanocobalamin absorption mechanism of rabbits is similar to that of human subjects and other laboratory animals.
Mechanism of splenic contraction produced by severe hypercapnia
Authors: Ramlo John H. , Brown E. B.
Published: December 2017

Unilaterally adrenalectomized and bilaterally adrenalectomized mongrel dogs with both normal and denervated spleen were made hypercapnic by inhalation of 30% CO2 in oxygen in order to determine the mechanism of the resulting splenic contraction. The results obtained indicate that splenic contraction in dogs breathing 30% CO2 is mediated by both the splenic nerves and by the adrenal glands. The nerves appear to act more rapidly but contraction still occurs in the absence of all innervation. Neither bilateral adrenalectomy nor splenic denervation alone completely blocked the splenic response in all animals, but of the two procedures the former appeared to be much more effective in this respect. In order to completely block splenic response to inhalation of 30% CO2, both denervation of the spleen and bilateral adrenalectomy were necessary.
Renin content of kidneys in experimental renal and human essential hypertension
Authors: Haas Erwin , Goldblatt Harry
Published: December 2017

The renin content of the ischemic kidney of dogs with experimental renal hypertension due to constriction of only one main renal artery was significantly elevated, while that of the contralateral, untouched kidney was abnormally low. Constriction of the main artery of one kidney and contralateral nephrectomy also resulted in hypertension and a great increase of renin in the ischemic kidney. In patients with hypertension accompanied by impairment of renal excretory function the renin content of the kidneys, the seat of arterial and arteriolar sclerosis, with or without accompanying pyelonephritis, was increased, on an average, to about four times that of normal kidneys, and, in individual cases, to as much as sixteen times the mean normal value. In this study, extraction of the renal tissue, after the freezing and thawing of the organ, yielded twice as much renin as previous extraction of the fresh tissue. The specific activity of the renin preparations from dog and human kidneys was enhanced twofold and fourfold, respectively, by means of revised methods for the extraction and partial purification of renin.
Effect of levarterenol on renal blood flow and vascular volume in dogs
Authors: Mehrizi A. , Hamilton W. F.
Published: December 2017

T-1824 was injected quickly into the renal artery of dogs and the renal vein stream was divided into samples every second. From the analysis of these timed samples a dye concentration curve was plotted and the flow and mean transit time were calculated. Since the flow calculated from the area of this curve agreed closely with the flow measured in the sampling tubes it was assumed that all the injected dye was recovered and that the mean transit time multiplied by the flow equaled the capacity of the active vascular channels. In seven animals the infusion of levarterenol produced an increase in renal vascular resistance without curtailing renal blood flow to such a degree that the dye curve could not be plotted. In these animals the arterial pressure rose, on the average from 109 to 176 mm Hg. This change in resistance reduced the renal blood flow from 120 to 84 cc/min., increased the mean transit time from 7.5 to 13.9 seconds and increased the volume of actively flowing blood from 15 to 17 cc (from 30 to 34 cc/100 gm of kidney). From these experiments it is concluded that the classical renal swelling from injection of epinephrine is the result of an increase in the resistance of post capillary segments of the renal vasculature and a distention of glomerular and possibly of peritubular capillaries.
Single proximal tubules of Necturus kidney IV. Dependence of H2O movement on osmotic gradients
Authors: Whittembury Guillermo , Oken Donald E. , Windhager Erich E. , Solomon A. K.
Published: December 2017

The relationship between net water flux and osmotic gradients across the Necturus kidney proximal tubule was studied with stopped flow microperfusion technique. To minimize water movement induced by Na transport, perfusion solutions contained 62.5 mm/l. NaCl; at this concentration no net water movement is observed with isosmolar solutions. Mannitol was added to prepare perfusion solutions with gradients ±70 mOs/l. relative to plasma. With these gradients, water movement was symmetrical in both directions across the membrane: tubular volume decreased 46% with hypoosmolar perfusion fluid, and increased 51% with hyperosmolar fluid. The membrane water permeability coefficient, Pf, is 0.15 x 10–8 ml/(cm2 sec. cm H2O). This coefficient permits calculation of net water movement ascribable to plasma protein osmotic pressure. The calculated value is approximately 1% of the fluid normally absorbed by the tubule. This conclusion was confirmed in separate experiments in which albumin was added to perfusion fluid to produce a protein concentration 67% higher than in plasma. Under these conditions, water was still absorbed from the tubule, indicating that proteins do not play a major role in water absorption.
Curare and low blood pressure effects on direct cortical responses
Authors: Ochs Sidney
Published: December 2017

The hypothesis that d-tubocurarine injected intravenously blocks synaptic transmission by a direct action in the cerebral cortex was examined. Injections of 3 mg/kg d-tubocurarine caused either no fall, moderate decreases, or complete obliteration of direct cortical responses (DCR's) with little return to control levels within 30–60 minutes. Blood pressure was recorded and drops to 50–60 mm Hg or below were associated with moderate to severe decreases of DCR's; drops below 40 mm Hg with elimination of the DCR. Diminishing the blood pressure to 50–60 mm Hg by bleeding resulted in moderately to greatly decreased DCR's. Bleedings to a pressure of 35–40 mm Hg might give rise to an ‘enhancing effect’ before DCR's were completely diminished. During enhancement DCR's became several times larger than control height. This effect was interpreted as a differential loss of an inhibitory component. Decrease of DCR's after injecting d-tubocurarine is considered secondary to the lower blood pressure.
Effect of small doses of 5-hydroxytryptamine (serotonin) on pulmonary circulation in the closed-chest dog
Authors: Shepherd John T. , Donald David E. , Linder Erland , Swan H. J. C.
Published: December 2017

5-Hydroxytryptamine (serotonin) was infused into anesthetized dogs at a rate of 20 µg/kg/min. In nine sets of observations on three dogs the increase in the difference of pressure between the pulmonary artery and the left atrium, which averaged 55%, consistently exceeded the increase in pulmonary blood flow, which averaged 16%. 5-HT therefore is a potent constrictor of pulmonary vessels, even in small concentrations. No changes in the pulmonary-artery wedge and pulmonary-vein pressures were detected during the infusions of 5-HT, nor was there any change in the volume of blood between the pulmonary artery and the root of the aorta. With this dose of 5-HT the principal site of the increased resistance to flow through the lungs appeared to be in the precapillary vessels. In the isolated perfused lung, moderate constriction of pulmonary veins also was produced by large doses of 5-HT.
Comparative effect of heparin and other agents on traumatic shock in the rat
Authors: Banaszak Edward F. , Stekiel William J. , Smith James J.
Published: December 2017

The effect of heparin and Aureomycin on Noble-Collip drum shock in rats was compared with that of autonomic blocking agents. Intravenous Dibenzyline (0.5 and 1.0 mg/kg) and Mecamylamine (2 mg/kg) notably reduced mortality when given 15–30 minutes prior to drumming. Heparin (2.5–10 mg/kg) and Aureomycin by mouth (150 mg/kg/day for 3 days) had no effect on mortality. Repeated sublethal trauma induced marked protection against drum shock. Concurrent administration of Dibenzyline did not prevent the development of this resistance. Repeated nonspecific stress and exercise failed to protect rats against drum shock suggesting that the development of ‘induced resistance’ is not related to elevated plasma catechol amines. The increased mortality of rats to drum shock incident to reticulo-endothelial blockade was mitigated if Dibenzyline was injected before blockade although not if given after.
Effect of sodium ion on contractility of the dog's aortic strip in response to catecholamines
Authors: Yamabayashi Hajime , Hamilton William F.
Published: December 2017

Effect of sodium ion on the dog's aortic strip was determined by measuring the tension produced by the isometric contraction of the strip in response to catecholamines during the incubation in Krebs' solution and in modified Krebs' solution in which the concentration of sodium chloride was varied. It was found that increasing sodium chloride in the solution to a certain amount, itself caused spontaneous contraction of the strip. The subthreshold addition of sodium chloride to Krebs' solution in an amount incapable of causing spontaneous contraction definitely potentiated the contractile response of the strip to a low concentration of catecholamines. Total removal of sodium chloride from Krebs' solution considerably depressed the contractility of the strip in response to catecholamines. It is suggested that sodium may importantly be involved in the development of some type of hypertension.
Multiple response to photic stimulation in cats
Authors: Fleming T. Corwin , Evarts Edward V.
Published: December 2017

This study was carried out in order to compare the multiple cortical response to a photic stimulus and the secondary response to sciatic nerve stimulation. Late responses to flash and to sciatic nerve shock were recorded in acute cat preparations anesthetized with pentobarbital. The responses to the two types of stimuli differed in distribution (visual multiple response confined to primary receiving area, sciatic secondary generalized), form and anesthetic level optimal for their production (deeper anesthesia for the sciatic secondary than for the visual multiple response). In cats with chronically implanted electrodes, it was found that the multiple response to flash was present during natural sleep and was abolished by arousal.
Effect of X-irradiation on hepatic carbohydrate enzymes in control and hypophysectomized rats
Authors: Weber George , Cantero Antonio
Published: December 2017

The sequence of metabolic events was investigated in rats for 8 days after exposure to 600 r total-body x-irradiation. The preirradiation studies showed that in hypophysectomized animals 18 hours of fasting reduced the activities of enzymes involved in glucose-6-phosphate utilization indicating that the hypophysis is involved in the physiological maintenance of these enzymatic activities. In control animals after irradiation fasting blood sugar and liver glycogen increased reaching a peak at 3 days and returning to normal range at 8 days postirradiation. Hepatic phosphohexoseisomerase and phosphoglucomutase activities indicated the presence of an increased glycogenesis and gluconeogenesis. Liver 6-phosphogluconate dehydrogenase activity increased to almost double the preirradiation value and stayed at this level during the whole postirradiation period. Glucose-6-phosphatase activity was not affected by irradiation. In hypophysectomized animals after irradiation blood sugar, liver glycogen and most enzymatic activities remained essentially in the preirradiation level, indicating that hypophysectomy abolished the characteristic carbohydrate metabolic response to radiation. The deficient metabolic reaction of hypophysectomized animals was correlated with the increased mortality rate in this group.
Effects of ganglionic blocking agents, pressor and depressor drugs on renal hypertension
Authors: Haas Erwin , Goldblatt Harry
Published: December 2017

The effects of ganglionic blocking agents and of pressor and depressor drugs were investigated in an analysis of the humoral mechanism of renal hypertension. The pattern of response of the blood pressure to the intravenous infusion of pentolinium is suggestive of the participation of renin at various stages of experimental renal hypertension. This was reaffirmed by the effectiveness of immunologically produced antirenin in inhibiting the pressor activity of renin and in lowering the blood pressure in hypertensive animals. Apresoline, nitroglycerin and sodium azide acted identically in lowering the blood pressure of both normotensive and hypertensive dogs and were therefore unsuitable for a study of the humoral mechanism of renal hypertension. The activity of various pressor agents was enhanced to different degrees in the hypertensive dog.
Absorption and distribution of S35O2 inhaled through the nose and mouth by dogs
Authors: Balchum Oscar J. , Dybicki Jerzy , Meneely George R.
Published: December 2017

Dogs breathing S35O2 through the nose and mouth retained a smaller proportion of the inhaled gas in the trachea, lungs, hilar lymph nodes, and liver and spleen than those breathing similar concentrations via a tracheostomy. This conclusion is substantiated by tissue S35 concentration assays, and measurements of the compliance of the lungs and thorax, and of pulmonary resistance. The upper airways therefore partially protect the lungs from exposure to sulfur dioxide.
Effect of rate of ingestion of diet on hexosemonophosphate shunt activity
Authors: Cohn Clarence , Joseph Dorothy
Published: December 2017

Young adult male rats either were allowed to eat ad libitum or were force-fed a high carbohydrate diet for 6–7 weeks; the latter animals were given amounts of diet that would "pair-gain" them against the former ones. At the end of the feeding period, the animals were killed and homogenates were made of hepatic and epididymal fat tissue or slices were prepared from the liver. The supernatants of the homogenates were assayed for glucose-6-phosphate (+6-phosphogluconate) dehydrogenase activity; the slices of liver were studied for their ability to oxidize either C-6- or C-1 C14-labeled glucose. The results of both types of measurements indicated that increased use was made of the hexosemonophosphate oxidative shunt by the tissues of the force-fed animals. It is concluded that the rate of ingestion of the diet plays a role in the regulation of traffic over specific enzymatic pathways, when multiple alternate pathways are available.
Hemodynamic changes in the ewe affecting fetal heart rate in utero
Authors: Bieniarz J. , Reynolds S. R. M.
Published: December 2017

Hemodynamic disturbances in pregnant ewes upon the fetus were studied and compared with respiratory anoxia. Vagus section and stimulation in the ewe or injection of humoral mediators produce hemodynamic disturbances in the mother, with fetal bradycardia. Comparison of active or passive congestion of the maternal placenta is accompanied by increase in umbilical vein pressure and/or umbilical artery pressure and fetal bradycardia. These hemodynamic factors on both sides of the placenta are closely interconnected. Disturbed respiration in the ewe is associated with hemodynamic responses of the maternal and fetal circulations. Increased intrauterine pressure is associated with increase in fetal blood pressures and bradycardia. With respiratory anoxia, fetal distress does not appear before hemodynamic disturbances in the ewe. The concept that hemodynamic disturbances in the maternal organism influence the fetus through changes in the uteroplacental circulation is advanced. Passive engorgement of an obstructed venous return or an active congestion resulting from an increased arterial inflow into the uteroplacental circulation affect the fetal part of the placental circulation resulting in bradycardia. The fetal vagus is involved; afferent pathways are not established.
Relation of saluretic and hypotensive effects of hydrochlorothiazide in the rat
Authors: Friedman Sydney M. , Nakashima Miyoshi , Friedman Constance L.
Published: December 2017

Hydrochlorothiazide causes a marked loss of Na and of water in both fully alimented rats and in rats deprived of food and/or water. The increased urinary volume corresponds closely to the shrinkage of the extracellular fluid volume (inulin space) but the decrease in extracellular Na is not sufficient to account for the Na excretion, suggesting that Na is withdrawn from cells and perhaps bone stores as well. The fall in blood pressure in hypertensive rats is not due to simple shrinkage of the extracellular space and plasma volume, but can be referred to the rise in Na gradient induced by withdrawal of cell sodium.
Effects of exposure to 5°C and advancing age on tissue mast cells and heparin in male rats
Authors: Marx L. , Hirota M. , Printup C. A. , Warnick M. A. , Marx W.
Published: December 2017

Mast cell counts and heparin concentrations in liver, lung, kidney, thymus and spleen, and serum heparin levels and blood clotting times were determined in two age groups of male rats, exposed to 5°C for 1 week, and in controls of the same ages kept at room temperature. It was observed that the mast cell counts from different regions of the same organ were similar. With advancing age, the mast cells became more numerous in lung and thymus and, to a lesser degree, in kidney. Cold exposure caused an elevation of the mast cell numbers in the younger group but a depression in the older animals; these changes were significant in lung and thymus. The heparin content of thymus rose with advancing age; a similar trend was seen in lung. Cold exposure had no effect on tissue heparin levels. The serum concentration of the anticoagulant was not influenced by age or external temperature, but the clotting time was elevated by both advancing age and cold environment.
Effects of glucose on fatty acid oxidation by diaphragms from normal and alloxan-diabetic fed and starved rats
Authors: Fritz Irving B. , Kaplan Eli
Published: December 2017

Palmitic acid-1-C14 oxidation by hemidiaphragms was measured in tissues from fed and starved normal and alloxanized rats. Muscle from normal rats starved for 3 days or longer showed an enhanced conversion of added palmitate to C14O2, while fasting for 1 or 2 days had little effect on fatty acid degradation by diaphragms from normal rats. Tissues from fed or starved alloxan diabetic animals had an augmented oxidation of labeled palmitate. The addition of glucose to the medium spared fatty acid oxidation by diaphragms from starved or diabetic rats but did not influence palmitate degradation by tissues from normal fed rats. The presence of insulin increased the glucose sparing action on long-chain fatty acid oxidation but was without effect on palmitate oxidation in the absence of added glucose. The conversion of C14-octanoic acid to C14O2 by muscle was not influenced by previous starvation nor by addition of glucose to the medium. Glucose-U-C14 and glucose-1-C14 conversion to C14O2 and glycogen were essentially the same in diaphragms from fed and starved animals.
Metabolism of purine derivatives by the isolated cat heart
Authors: Jacob Miriam I. , Berne Robert M.
Published: December 2017

Perfusion of the isolated cat heart with Tyrode's solution containing adenosine, adenosine-8-C14 or ATP induced an increase in coronary flow and in the amount of inosine and hypoxanthine in the perfusate compared to the results obtained by the perfusion of Tyrode's solution alone. Perfusion of the cat heart with inosine did not induce coronary vasodilation. Adenosine deaminase and nucleoside phosphorylase were leached out of the isolated cat heart preparation during the perfusion process. Adenosine, added to perfusate collected after one passage through the cat heart, was converted to inosine and hypoxanthine. When the heart was perfused with adenosine-8-C14 approximately 50% of the adenosine entered the myocardial cells where it was trapped as adenine nucleotide, whereas the remainder was recovered in the perfusate as inosine and hypoxanthine. Perfusion of dinitrophenol induced coronary vasodilation and an increase in the amount of inosine and hypoxanthine recovered in the perfusate. It is postulated that the dinitrophenol effects the release of adenosine from the myocardial cells and thereby produces coronary vasodilation.
Cardiovascular responses to electrical stimulation in the diencephalon
Authors: Manning John W. , Peiss Clarence N.
Published: December 2017

Cardiovascular responses to stimulation of the diencephalon have been recorded in vagotomized cats under d-tubocurarine or alpha-chloralose anesthesia. These responses include vasoconstriction, augmentation of myocardial contraction and cardioacceleration. These types of response may occur as single phenomena, but more commonly the response consists of various combinations of the three phenomena. It has been demonstrated in many animals that the major component of a pressor response is often the result of increased force of myocardial contraction rather than vasoconstriction. The highly reactive area for eliciting these responses includes the lateral and posterior hypothalamus, and part of the subthalamus. The area is bounded rostrally by a plane through the posterior border of the optic chiasma, caudally by a plane through the anterior border of the red nucleus, dorsally by a plane through the ventral thalamic nuclei, and laterally by a plane 3–4 mm to each side of the mid-line.