bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of cortisone on magnesium metabolism in the rabbit
Authors: Aikawa Jerry K. , Harms Dale R. , Reardon Jacqueline Z.
Published: December 2017

External balance studies for magnesium and serial isotopic determinations of the exchangeable magnesium content were made in seven adult male rabbits before and during a 14-day series of daily injections of cortisone acetate (10 mg/kg of body weight). A significant reduction in serum magnesium concentration was found at 8 and 14 days. The exchangeable magnesium content was increased at 8 days. In another group of animals relative tissue activity studies showed that the uptake of Mg28 by the heart, appendix and muscle was increased on the 8th day of cortisone administration. The results suggest that this dose of cortisone does not alter the external balance of magnesium, but that a more subtle internal change in the dynamics and distribution of magnesium does occur.
Measurement of total energy and material balance in rats by means of doubly labeled water
Authors: Lee J. S. , Lifson Nathan
Published: December 2017

A test has been carried out in rats of the possibility of measuring with the aid of doubly labeled water (D2O18) the following components of the material balance of an animal: output of CO2 and water; intake of oxygen, food and water. The items of information used for the measurement were a) isotopic analyses of initial and final blood samples, b) composition of the diet with respect to percentage protein, carbohydrate and fat, c) initial and final body weight, d) final percentage body water. Initial percentage body water obtained from a by the volume of dilution principle could substitute for d. CO2 and water output were estimated isotopically; O2 consumption, from the CO2 output and dietary R. Q.; food intake, from CO2 output and dietary composition; water intake, from the difference between water output and dietary metabolic water. A rough correction for storage of materials was made from the change in body weight. The average difference between observed values for each of the above components of the material balance and values calculated by the isotope procedure was less than 10%. The fact that dry air was supplied to the animal in the metabolism chamber used to obtain the observed values probably favored better agreement between calculated and observed values for water intake and output than would prevail in ordinary moist air.
Depressed lipogenesis induced by cold stress
Authors: Masoro E. J.
Published: December 2017

Liver homogenates were prepared from control, cold-fed and cold-fasted rats. Homogenates from control and cold-fed rats synthesized fatty acids to about the same extent. However, homogenates from cold-fasted rats converted far less acetate-1-C14 to fatty acids than homogenates from control and cold-fed rats. Previous studies showed that lipogenesis is depressed in liver slices from both cold-fed and cold-fasted rats. Probably the fact that lipogenesis is inhibited in the intact liver cells of cold-fed rats is not the result of reduced levels of fatty acid-synthesizing enzymes but is the result of an unfavorable cofactor environment; the evidence indicates that a low rate of TPNH generation via the hexose monophosphate pathway of carbohydrate metabolism causes the reduction in lipogenic activity. The failure in lipogenesis in the liver cells of the cold-fasted rat appears to result from quite a different cause than that of the cold-fed rat. The most likely reason for the low rate of lipogenesis in the liver of cold-fasted rats appears to be the loss of the fatty acid-synthesizing enzymes; however, the possibility that this lipogenic defect is related to the lack of a cofactor—as yet undiscovered— cannot be discounted.
Autoregulation absent in normal kidney but present after renal damage
Authors: Langston Jimmy B. , Guyton Arthur C. , Gillespie William J.
Published: December 2017

Experiments of this study indicate that the kidney does not normally autoregulate its blood flow; in these experiments a change in perfusion pressure always resulted in a corresponding change in renal blood flow when the kidney was not subjected to surgical trauma. On the other hand, when renal ischemia was induced or when the perirenal tissues were intentionally damaged, autoregulation of renal blood flow occurred in every instance. Two possible theories are discussed for this autoregulation: a) blockage of the renal lymphatic drainage and b) disruption of the blood supply to the walls of the renal and intrarenal arteries.
Release of renin in hypertensive rats
Authors: Omae Teruo , Masson Georges M. C. , Page Irvine H.
Published: December 2017

A method for perfusing rat's kidneys is described in which renal release of pressor substances (renin?) was measured by grafting a kidney on to a 24-hour nephrectomized recipient. Normal kidneys provoked a sharp and sustained rise in blood pressure. Kidneys that had undergone compensatory hypertrophy behaved as normal kidneys as long as the animals received tap water to drink; when 1% saline was substituted, pressor activity decreased gradually and finally disappeared usually around the 3rd week. DCA injection (2 mg/day) enhanced the salt effect so that no pressor activity could be demonstrated after the 4th day of treatment. Kidneys from rats with post-DCA or adrenal regeneration hypertension did not release pressor material. Unilateral renal infarction associated with contralateral nephrectomy caused initially a decrease in renin release followed by disappearance in both the rats that developed hypertension and in some that remained normotensive. Since absence of pressor activity in the renal venous effluent as determined by this method is not necessarily associated with development of hypertension, it is possible that this change represents primarily a response to renal injury, sodium excess and/or high blood pressure.
Removal of excess body potassium by hemodialysis
Authors: Tu W. H. , Bair Glenn O. , Schloerb Paul R.
Published: December 2017

Potassium has been removed acutely from nephrectomized potassium-loaded dogs by hemodialysis while other electrolyte concentrations were maintained constant. Potassium extraction occurred in a rapid phase with a decrease of plasma potassium concentration and in a second phase of continued extraction with no change of plasma potassium concentration. Hypopotassemia and electrocardiographic changes of hypopotassemia appeared while the dogs remained in net positive potassium balance. P wave amplitude showed a tendency to decrease following loading of potassium and increased following removal of potassium from the dogs. The change of P wave amplitude following loading of potassium showed significant multiple correlation with plasma and myocardium potassium concentrations, and with the ratio of myocardium/plasma potassium concentration alone, but not with either plasma or with myocardium potassium concentration alone.
Active transport by intestines of fetal and newborn rabbits
Authors: Wilson T. Hastings , Lin Edmund C. C.
Published: December 2017

Everted sacs of intestine from fetal or 3-day-old rabbits were found to transport glucose, 6-deoxy-d-glucose, galactose and l-histidine against concentration gradients aerobically. Active transport was also demonstrated for 6-deoxy-d-glucose, l-tyrosine and l-histidine under anaerobic conditions. The capacity to transport l-histidine anaerobically was found to decrease rapidly during the 1st week after birth, while the aerobic transport rate increased slightly.
Iodine deficiency in newborn rats
Authors: Feldman Joseph D.
Published: December 2017

The pups of iodine-deficient rats were cretinoid in appearance and had thyroids which were enlarged and hyperactive. By radiochromatographic analysis, the neonatal deficient thyroids were similar in all respects to the composition of adult iodine-deficient glands. In intact dams, exogenous thyrotropin (TSH) did not affect the fetal thyroid. In thyroidectomized dams, the fetal thyroid was hyperactive. The thyroidal alterations in newborns of iodine-deficient dams were most likely the result of fetal iodine deficiency, although placental transfer of maternal TSH could not be entirely excluded.
Exogenous plasma magnesium increases during hypothermia in dogs
Authors: Moussa Salah L. , Boba Antonio
Published: December 2017

It has been reported and our observations have confirmed that during immersion hypothermia in nonhibernators the plasma magnesium level will exhibit an increase linear to the fall in core temperature. In the present study the parenteral administration of magnesium sulphate during immersion hypothermia produced increases in plasma magnesium levels, which were associated, however, with a decreased tolerance to exposure, a higher rate of ventricular fibrillation and a higher lethal temperature. It is likely that the plasma magnesium level increase, even though linear to the fall in core temperature, is not the factor which influences tolerance to exposure. The factor would rather be the ability of the organism to unload magnesium from its stores, of which ability plasma magnesium levels would be a mere reflection.
Comparison of Cr51 RBC, I131-tagged albumin, I131-tagged rose bengal and I131-tagged Diodrast for cardiac output
Authors: Crane M. G. , Holloway J. E. , Selvester R. , Crawford R.
Published: December 2017

Tagged rose bengal and tagged Diodrast were each compared with tagged red blood cells as indicators of central flow rate and central volume in the dog. Tagged rose bengal was unsuitable because it stained the plastic tubing used to convey the blood sample through the well crystal. The average cardiac output by tagged Diodrast was 0.8 ± 5.5% greater than that by tagged red cells. The average volume of dilution by tagged Diodrast was 4.9 ± 6.4% greater than by tagged cells. The slightly larger volume of dilution obtained by the plasma phase could be explained by the greater mean circulation time for plasma as compared with that of associated red cells in small blood vessels. RISA and tagged Diodrast were compared by 10-minute spaced injections in 11 patients at cardiac catheterization. The average cardiac output by tagged Diodrast was 0.3 ± 5.2% greater than that by RISA. The average volume of dilution by tagged Diodrast was 0.8 ± 8.9% lower than that by RISA.
Effect of insulin on cardiac metabolism of intact normal dogs
Authors: Hackel Donald B.
Published: December 2017

The coronary sinus, pulmonary artery and aorta of intact normal dogs were catheterized and coronary blood flow (N2O desaturation method) cardiac output (Fick with O2) and myocardial O2, CO2, glucose, lactate and pyruvate extractions were determined. Measurements were repeated at intervals after an intravenous injection of insulin. Insulin caused a marked decrease in the myocardial threshold for glucose in normal dogs so that there resulted an increase in percentage extraction (A-V/A. 100) of glucose despite decreased arterial levels. This is in accord with the increased threshold for glucose previously observed in diabetic patients. The observations are consistent with the hypothesis that insulin facilitates the transfer of glucose into the cell. There was no significant change in the myocardial R. Q., a finding which was presumably due to the decreased blood glucose levels. Insulin did not alter the arterial levels, extraction or total utilization of lactate or pyruvate by the heart.
Hormonal and pharmacologic influences on microcirculation in the rat stomach
Authors: Dolcini Horacio A. , Zaidman Isidoro , Gray Seymour J.
Published: December 2017

Hormonal and pharmacologic influences on the microcirculation of the stomach have been studied in rats. The blood content of the gastric mucosa was evaluated quantitatively by densitometric measurement of the India ink content of the mucosa following intra-aortic injection of India ink in the living animal. An aortic by-pass procedure was developed utilizing a polyethylene catheter through which India ink could be injected without opening the abdomen, thus avoiding reflex influences upon the gastric blood content. An increase in the gastric mucosal India ink content was observed following the administration of ACTH, serotonin, 5-hydroxytryptophan, Mecholyl and Dibenzyline. A decrease in the mucosal India ink content was noted after adrenalectomy and epinephrine. These studies suggest that hormonal and pharmacologic influences upon the gastric microcirculation are exerted by direct action on the capillary vessels, by neural influences or by the response to increased metabolic activity.
Sodium and potassium in erythrocytes of adult and fetal goats
Authors: Blechner Jack N.
Published: December 2017

Sodium and potassium concentrations in the erythrocytes of adult and fetal goats were estimated by flame photometry. In the fetus there is a higher potassium and a lower sodium concentration than in the adult. The mean fetal potassium concentration is 104.8 mEq/l. of red cells and the sodium 15.8; the maternal values are 68.4 and 35.4, respectively. Pregnancy does not appear to alter the sodium and potassium concentrations in adult goat erythrocytes. Moreover, the fetal levels show no change with advancing gestation, from the 52nd to the 142nd day. The sodium and potassium gradients between the red blood cells and the plasma in fetal blood are higher than in maternal blood and suggest the possibility of an increased energy expenditure by fetal erythrocytes. The findings lend support to the hypothesis that the ionic environment within the red cell is one of the factors contributing to the differences between the oxygen dissociation curves of fetal and maternal whole blood.
Relationship of pressure to blood flow in the dog kidney
Authors: Hardin Robert A. , Scott Jerry B. , Haddy Francis
Published: December 2017

Perfusion of the dog kidney via the aorta with no interruption of renal blood flow or disturbance of the kidney or its immediate physical surroundings revealed perfusion pressure-blood flow relationships similar to those previously reported for semi-isolated and isolated kidneys. This suggests that the kidney in the completely intact animal has a local mechanism for holding its blood flow constant despite changes of arterial pressure over the approximate range 70–200 mm Hg.
Distribution of urea, thiourea-C14 and sucrose-C14 in dog kidney during antidiuresis
Authors: Bray George A.
Published: December 2017

The distribution of urea, thiourea-C14 and sucrose-C14 in the kidney and urine during antidiuresis has been investigated. An inverse relationship between the urine to papilla ratio and the papilla to cortex ratio for these three compounds has been demonstrated. For urea, the urine to papilla ratio is only 1.5, while the urea concentration in the papilla is 14 or more times that in the cortex. Studies with sucrose-C14 showed a urine to papilla ratio of 20 or more while the papilla sucrose-C14 concentration was only three to four times as high as the cortex. Thiourea-C14 behaved in a manner similar to urea, with high concentrations of isotope in the papilla and a urine to papilla ratio of 9. These results have been discussed in terms of the permeability of the collecting duct and the countercurrent exchanger function of medullary blood flow.
Effects of epinephrine and norepinephrine on lipid metabolism of the rat
Authors: Friedman Meyer , Byers Sanford O.
Published: December 2017

Administration of either epinephrine or norepinephrine was found to have little or no effect upon the intestinal absorption of cholesterol, phospholipid or triglyceride. Similarly administration of either catecholamine did not appear to affect the hepatic metabolism of cholesterol as judged by cholesterol and cholate analyses of bile. Starved animals infused with either catecholamine failed to exhibit any serum change in cholesterol or phospholipid. However, a modest rise in triglyceride was observed either 12 or 24 hours after infusion. If the animals were fed cholesterol and triglyceride, a slight rise in all serum lipids was observed at the end of 24 hours of infusion. Animals injected thrice weekly with either epinephrine or norepinephrine in oil for a period of 120 days exhibited approximately the same serum lipid values as the control animals. The conclusion is reached that little or no permanent effect on the lipid metabolism of the rat is achieved by administration of either catecholamine.
Heart rate and O2 consumption after triiodothyronine in the myxedematous rabbit
Authors: Guz Abraham , Kurland George S. , Freedberg A. Stone
Published: December 2017

The basal oxygen consumption and heart rate of the myxedematous rabbit has been studied following the intravenous injection of 200–400 µg of triiodothyronine. The heart rate increased in 1–3 hours after injection which was invariably before the onset of the rise in oxygen consumption at 3.5–14 hours after injection.
Effect of dinitrophenol on phosphorylation and bioelectric phenomena of excitable tissues
Authors: Abood L. G. , Koketsu K. , Noda K.
Published: December 2017

The effect of 2, 4-dinitrophenol (DNP) was investigated on the phosphorylation of frog sartorius muscle and ventral nerve roots, using P32 as a tracer. It was possible almost completely to inhibit phosphorylation without significantly altering excitability, although the resting potential and intracellular potassium decreased over 30%. The addition of 0.01 mm DNP to a sodium-free hydrazinium system completely blocked excitability, despite the fact that this concentration of DNP produced no further inhibition of phosphorylation. It was possible to restore the excitability of frog sartorius muscle fibers by anodal polarization after the fibers were rendered inexcitable by immersion in 1 mm DNP. The results were discussed in terms of the role of energy metabolism in excitability and other bioelectric phenomena of muscle and nerve.
Temperature and salt effects on water and electrolyte metabolism of thyroid slices
Authors: Boatman Joseph B. , Pisarcik Patricia A.
Published: December 2017

Groups of bovine thyroid slices were incubated under oxygen with shaking for 1 hour at temperatures from 10° to 40°C in 5° increments, and at 38°C with media of 0.7, 0.8, 0.9 and 1.0% sodium chloride. The media of tissues at each temperature or salinity gradient contained Na24, I131 or I131-4-iodoantipyrine. Pre- and postincubation wet weights and final dry weight, gain in water and gain of radioactivity during incubation of tissue slices at each gradient was measured. With rising temperature gradients I131 uptake by slices increased, and with increased salinity I131 uptake decreased. In both cases, with increased gradients, the degree of swelling was decreased, Na24 space remained unchanged and the I131-antipyrine space increased compared to the media. It was concluded the response of thyroid slices to the external environment could be best explained in terms of the anatomical structure of the follicle. The metabolic effects of temperature and osmotic changes directly influenced the metabolism of water and electrolytes of the thyroid slice and were reflected in changes of I131 metabolism.
Ultrafilterability of endogenous antidiuretic hormone from plasma of dogs
Authors: Bocanegra Manuel , Lauson Henry D.
Published: December 2017

External jugular blood removed during the last half of a fatal hemorrhage in pentobarbital-anesthetized dogs given hypertonic saline into the ipsilateral carotid artery was rich in antidiuretic activity when assayed by intravenous injection in conscious, hydrated female dogs or ethanol-anesthetized rats. The antidiuretic activity in this plasma was in all probability due to neurohypophysial vasopressin: a) its renal effects were qualitatively the same as those of bovine Pitressin and purified arginine vasopressin; b) the antidiuresis resulting from injection of such plasma was not due to histamine or ferritin; c) the activity was destroyed by thioglycollate, trypsin and chymotrypsin but was resistant to pepsin and carboxypeptidase. Practically all of the antidiuretic activity in hemorrhaged dog blood was contained in the plasma; none was adsorbed by or permeated into erythrocytes. About three-fourths of the ADH in this plasma circulated in a form permitting it to be ultrafiltered through cellulose tubing at 4°C under pressure supplied by 5% carbon dioxide in oxygen. These data and those of others indicate that there is a marked species difference between the dog and rat with respect to the extent that endogenous vasopressin is bound to plasma proteins.
Splanchnic blood volume in traumatic shock
Authors: Friedman J. J.
Published: December 2017

The distribution of radioiodinated plasma and radioiron-labeled red blood cells between the liver, intestine and spleen were determined during the induction and development of tourniquet shock in mice. The data obtained indicate that plasma and red blood cells are distributed differentially throughout the splanchnic vasculature such that plasma volume of liver, intestine and spleen remain depressed for the entire shock interval, as does splenic red cell volume. After an early decline, the red cell volume of liver and intestine become elevated to a level above control. This differential distribution of plasma and red cells in liver and intestine is attributed to alterations in peripherovascular tone and suggests that a venous component becomes prominent late in shock and may act to pool blood out of active circulation.
Complementary role of adrenal cortex and salt in adrenal-regeneration hypertension
Authors: Oelsner Thomas , Skelton Floyd R.
Published: December 2017

The relationship between salt ingestion and regenerating adrenal cortical tissue in the genesis of adrenal-regeneration hypertension has been studied by varying the content of sodium chloride in the diet from 2.5 to 10%. Results indicate that adrenal-regeneration hypertension is the product of an interplay between the hypertensive potentials of sodium chloride and regenerating adrenal cortical tissue. In young, female rats, enucleation and subsequent regeneration of the adrenal cortex has a hypertensive potential of itself which may be inhibited by low salt ingestion, overshadowed by excessively high salt ingestion and optimally demonstrated by salt consumption approximating 5% of the daily food intake. On the other hand, sodium chloride has an independent hypertensive potential, which is consistently augmented by the presence of a regenerating adrenal gland. Whatever adrenal cortical factors are involved, they are not altered by bilateral adrenal enucleation nor are they mimicked by unilateral adrenalectomy or sham adrenal enucleation.
Renal function studies in the dog hypophysectomized for ascites
Authors: Craig Robert L. , Wetzel Nicholas , Bianchi Robert G.
Published: December 2017

Dogs with experimental ascites have a depressed glomerular filtration rate and renal plasma flow which are further depressed after ascites disappears as a result of hypophysectomy. However, sodium clearance, depressed with ascites, returns to normal after hypophysectomy. The Na/K ratio is depressed with ascites and increases after hypophysectomy.
Quantitation of cerebral ischemic pressor response in dogs
Authors: Sagawa Kiichi , Ross Joe M. , Guyton Arthur C.
Published: December 2017

Using a surgical technique designed to isolate the cerebral arterial circulation from the systemic and extracranial circulations and also a servomechanism devised to prevent blood volume shift between a donor dog and an experimental dog, the experimental dog's brain was perfused at a succession of controlled arterial pressures ranging from 140 to 0 mm Hg for the purpose of investigating quantitatively the steady-state response of the systemic arterial pressure (SAP) to stepwise changes of cerebral perfusion pressure (CPP) and cerebral blood flow (CBF). The interrelationships between CPP and SAP suggested a rectangular hyperbolic curve, but this same relationship was more clearly demonstrated when SAP was plotted against CBF. These findings suggest a chemical rather than pressoreceptor basis for the ischemic response. The peak values of ΔSAP/ ΔCPP in individual cases varied from 11.4 to 3.1 and averaged 7.7; thus the response was found to be four or more times as powerful as the carotid sinus pressoreceptor reflex in dogs.
Size of microspheres passing through pulmonary circuit in the dog
Authors: Ring Gordon C. , Blum A. S. , Kurbatov T. , Moss W. G. , Smith W.
Published: December 2017

After injection of microspheres into the pulmonary artery approximately 50% of spheres 2.8–4.0 µ in diameter can be found in the systemic circuit during the first circulation, but only 6% of those 8 µ or larger get through the pulmonary circuit when compared with simultaneously injected tagged erythrocytes. If vessels are impeding the flow of spheres and are circular in cross section, then more than half of the erythrocytes must be distorted while passing through the pulmonary circuit. A continuous infusion of norepinephrine (1–4 µg/kg/min) brings about a reduction in the percentage of the various sizes of spheres passing through the pulmonary vessels. This suggests vasoconstriction. Acetylcholine iodide (13–40 µg/kg/min) usually diminishes the percentage of spheres 2.8 µ and smaller, which can go through the pulmonary circuit, but increases the percentage of microspheres 5.7 µ and larger. During prolonged inspiration the percentage of microspheres passing through in each group studied was less than during expiration. If all microspheres injected are to pass through the pulmonary circuit in inspiration they must be 1.4 µ or smaller.
Intestinal ischemia shock in normal and Dibenzyline-protected dogs
Authors: Hershey S. G. , Baez S. , Rovenstine E. A.
Published: December 2017

An experimental model was developed to facilitate study of the intestinal-hepatic complex in shock. Shock was produced by ischemic injury to the intestine by temporary (4-hr) ligation of the superior mesenteric artery (SMA shock). Protection against shock was induced by Dibenzyline injected into the portal vein. Blood samples before, during, and after arterial occlusion were taken from the femoral, portal, and hepatic veins for hemoglobin, hematocrit, plasma proteins, bacterial culture, endotoxin detoxifying component (EDC), and vasotropic assays (rat mesoappendix). Liver biopsies were taken for carbon distribution in the Kupffer cells. Blood pressure and tissue temperatures were monitored. The data indicate that these parameters of SMA shock are predictable and typical of other types of experimental shock and can be attenuated by Dibenzyline. Bacterial organisms and polysaccharides (EDC) were not present in irreversible shock. Vasotropic assays demonstrated vasodepressor (epinephrine inhibiting) materials, in the peripheral blood. Vasodepressor responses were abolished by the action of Dibenzyline on hepatic function, possibly by sustaining hepatic reticuloendothelial system activity.
Active transport of calcium by intestine: effects of dietary calcium
Authors: Kimberg Daniel V. , Schachter David , Schenker Harris
Published: December 2017

The small intestine of the rat responds facultatively to a diet low in Ca by increasing the active transport of the cation. The effects of calcium deprivation were studied with everted gut sacs and with duodenal slices in vitro, and the experiments demonstrate that following this stimulus almost the entire small intestine of a young rat can transfer calcium from the mucosa to the serosa against concentration gradients. The active transport is maximal in duodenum, less in ileum, and least in the mid small intestine. Following the low-Ca diet, duodenal gut sacs transport Sr89 against concentration gradients, although strontium is transferred much less readily than is calcium. Vitamin D is required for the adaptive response of the active transport in duodenum and ileum. Younger rats respond to Ca deprivation earlier and more markedly than older animals. Neither thyroparathyroidectomy, hypophysectomy, or adrenalectomy prevent response to the low-Ca diet, although these ablations do affect the active transport mechanism in rats on a given diet.
Enhancement by hypophysectomy of insulin effect on extrahepatic galactose transfer
Authors: Kokka Norio , Bennett Leslie L.
Published: December 2017

Fasted, normal, and hypophysectomized rats were eviscerated and nephrectomized under light pentobarbital anesthesia. Glucose was infused intravenously at rates that maintained a nearly constant blood glucose concentration. Single injections of galactose were given that produced an equilibrium concentration at 60 min of 247 ± 30 mg%. The galactose level was not significantly different at 90 min. Thus insulin could be administered at 60 min and the 60–90 min blood galactose change used as an index of insulin action. The extrahepatic uptake of galactose in hypophysectomized rats was demonstrated to be hypersensitive to insulin by two criteria: a) significant decreases in blood galactose concentration of hypophysectomized rats were produced by 0.01 unit of insulin/kg, a dose that had no effect on normal rats; b) after 0.02 unit of insulin/kg, changes in blood levels of galactose were greater in hypophysectomized rats than in their normal controls. Hypophysectomy did not alter galactose distribution volume. In neither normal nor hypophysectomized rats did prior administration of growth hormone alter either volume distribution of galactose or insulin hypersensitivity.
Autoregulation of blood flow in resting skeletal muscle
Authors: Stainsby Wendell N. , Renkin Eugene M.
Published: December 2017

Blood flow through the vascular beds of innervated and acutely denervated gastrocnemius-plantaris and gracilis muscles of dogs was studied following sudden changes of perfusing pressure or blood flow. These skeletal muscles were found to exhibit autoregulation of blood flow. An increase in perfusion pressure or flow is followed by an increase in resistance to blood flow, and a decrease in perfusion pressure or flow is followed by a reduction in resistance to flow. Consequently, blood flow changes relatively little over a wide range of perfusion pressures. The transient and steady state flows related to this phenomenon are analyzed in an attempt to establish the mechanisms involved.
Active reflex dilatation in the innervated perfused hind leg of the dog
Authors: Beck Lloyd
Published: December 2017

Epinephrine or norepinephrine was injected intravenously to produce reflex dilatation in the perfused hindquarters of the dog. A delay system permitted reflex effects to become maximal before arrival of the injected drug into the perfused area. Local sympathectomy of the perfused area abolishes the dilatation, thus demonstrating that the dilatation is reflex in origin. The reflex dilatation is partially active in nature because the magnitude of reflex dilatation exceeds the fall in perfusion pressure produced by sympathectomy of the perfused area. Evidence has been obtained that different sympathetic fibers mediate reflex constriction and reflex dilatation.
Effect of oral antimicrobial agents on absorption of cholesterol
Authors: Setty C. S. N. , Ivy A. C.
Published: December 2017

Rats were fed a sterol, fat free synthetic diet plus 9% corn oil, the sterol content being known. One group received streptomycin and Sulfasuxidine in the diet at a level of 0.2% and 1%, respectively; another, 200 mg and 500 mg daily of Terramycin and Sulfathalidine (TS), respectively. Cholesterol-4-C14 was added to the diet, and the fecal C14 in the unsaponifiable (UM) and the digitonin-precipitable material (DM) and the "bile acid fraction" was determined. The antimicrobial agents had no significant effect on the output of C14 in the UM. In the TS, the output of C14 in the UM and DM was the same, showing that a marked reduction in intestinal flora prevents the change of digitonin-precipitable into nondigitonin-precipitable material. The C14 output in the UM or DM was used as a basis for calculation, and 68 and 76%, respectively, of the dietary cholesterol was absorbed. In the TS group, using either the UM or the DM, the absorption was 70%. The differences represented by the three percentages are not statistically significant.
Kinetics of iron absorption in normal dogs
Authors: Stewart W. B. , Gambino S. R.
Published: December 2017

By means of the simultaneous use of two radioactive isotopes of iron, it has been possible to measure the rate of iron absorption from the gastrointestinal tract in normal dogs. One isotope was administered orally and another intravenously. By suitable calculation the rates of absorption at any given time were computed. Absorption begins at a very high rate, which varied from 22.8 µg/hr to 578 µg/hr in different dogs. The half-time of the absorption rate varied from 0.25 to 0.66 hr. The rapid fall in the rate of iron absorption is not caused entirely by the passage of the labeled material along the intestinal tract, but seems rather to be caused by the development of an inhibitory mechanism or the presence of a rate-limiting reaction in one of the steps in the passage of iron from the intestinal lumen to the plasma.
Urease poisoning in the dog
Authors: Handford Stanley Wing
Published: December 2017

Ammonium intoxication in dogs was induced by intravenous administration of urease. This method affords a unique preparation for the study of ammonia metabolism in vivo, since, within limits, a self-perpetuating, cyclic release of ammonia is achieved. Through the action of the enzyme, NH3—N is released from urea to be resynthesized via the ornithine-arginine cycle, operating in liver, to urea, from which in turn the ammonia nitrogen is released. Measurements of blood NH3—N, plasma NH3—N, BUN and plasma glutamine before and at 5, 30, and 60 minutes post intoxication show a highly significant increase in plasma glutamine and NH3—N levels and a decrease in BUN following ammonium intoxication. In showing that glutamine synthesis plays a major role in the clearance of an "overload" of NH3—N from the blood, and presumably other tissues, these results are in good agreement with the findings of other investigators.
Influence of age, adrenalectomy, and corticosteroids on hepatic transaminase activity
Authors: Harding Homer R. , Rosen Fred , Nichol Charles A.
Published: December 2017

The activity of alanine-α-ketoglutarate transaminase in rat liver was found to be uniform during the first 6 weeks of life, increasing thereafter until at 48 weeks of age the specific activity was seven times greater than in the immature rat. In rats varying in age from 4 days to 24 weeks, treatment with 1 mg of cortisol for 4 days resulted in significant increases in hepatic alanine transaminase activity. Female rats were less responsive to cortisol treatment than were males. Fetal rat liver had significantly lower alanine transaminase activity than did newborn animals and the activity of this enzyme in fetal liver was not altered by cortisol treatment. Adrenalectomy of adult male rats, but not immature male rats, resulted in a decrease in alanine transaminase activity; after 48 hr, enzyme activity was depressed to levels found in unoperated immature rats. The sensitivity of the adrenalectomized animals to cortisol administration was comparable to that of intact animals. In contrast, the aspartate-α-ketoglutarate transaminase was not appreciably altered following cortisol treatment or adrenalectomy and did not increase with age.
Tris buffer, CO2, and sympatho-adrenal system in reactions to O2 at high pressure
Authors: Bean John W.
Published: December 2017

The demonstration of the efficacy of tris(hydroxymethyl)aminomethane ("tris") in buffering tissue Pco2 and acidity suggested that it might provide protection against the toxic action of oxygen at high pressures (OHP). Experiments were therefore carried out on 72 pairs of albino rats. The test animal of each pair was administered tris intraperitoneally and subcutaneously and its control of equal body weight and age was given an equal volume of physiological NaCl solution in a similar manner. The usual dose was 1.5 g/kg body weight, as a 10% solution in physiological NaCl. Each pair was exposed separately. It was found that tris provided a pronounced degree of protection against the toxic action of OHP. It postponed the onset of the O2 seizures and decreased their incidence and severity. Lung damage was either absent or much less severe in the test animals than in the controls. The lung weight was less and the mortality rate much lower in the test than in the control animals. Statistically, the results, as measured by each of the criteria used, were highly significant ( P < 0.01). The results are important not only because they demonstrate that tris provides a pronounced measure of protection against the toxic action of OHP, but also because they redirect attention to increased tissue Pco2 and tissue [H+] concentration as possible contributors to the precipitation of the toxic reaction to OHP.
Variability of gastric secretory response to insulin hypoglycemia in fistulous beagle dogs
Authors: Davis Richard A. , Brooks Frank P.
Published: December 2017

The gastric secretory response to a uniform dosage of insulin (1.5 U/kg) was studied in seven beagle dogs with a Thomas fistula. The resting secretion was mucoid in character and alkaline. Variations in acid output after insulin stimulation showed a parallel reduction of volume and concentration, indicating that these changes were not the result of incomplete sample collections. In 43 of 50 insulin experiments, maximum gastric output occurred between 30 and 60 min after insulin administration. Thirty minutes after insulin there was a mean 42.5% reduction of blood glucose below fasting values, although the exact time of the nadir could not be determined. Different experiments in the same animal showed no statistical correlation between blood glucose levels and acid concentration or output. A late phase of gastric secretion was defined as an increase in acid output of 0.5 mEq/30 min which occurred at least 120 min after insulin administration. Late phases were seen in eight experiments, seven of which occurred in two animals. In the remainder of the experiments, initial maximum acid output was reached within 60 min and the basal state was reached within 180–240 min, when the blood glucose values had returned to fasting levels.
Pancreatic enzyme secretion produced in the rat by trypsin inhibitors
Authors: Lyman R. L. , Wilcox Sue Stewart , Monsen E. Ranker
Published: December 2017

In previous experiments, rats fed soybean trypsin inhibitor exhibited an exaggerated secretion of principal pancreatic digestive enzymes, as measured by the enzyme activities of the pancreas and intestine shortly after feeding. The present experiments studied the effect of trypsin inhibitors from egg white and lima bean on this pancreatic response in the rat. The influence of atropine and bilateral vagotomy on such secretion was also investigated. Both egg white and lima bean trypsin inhibitors evoked pancreatic enzyme secretion similar to that produced by soybean trypsin inhibitor. Inactivation of the inhibitors by reaction with crystalline trypsin prior to feeding did not impair the response. The physiological activity of these substances appeared to be closely associated with their trypsin inhibitor activity, yet inactivation of endogenous trypsin in the small intestine seemed not to be necessary for the response. Although vagotomy or a parasympathetic blocking agent did not suppress the pancreatic response to soybean trypsin inhibitor, no evidence for the release of a humoral factor by the inhibitor was obtained by cross-circulation observations.
Secretion and effect of hydrochlorothiazide in bile and pancreatic juice
Authors: Pratt E. B. , Aikawa J. K.
Published: December 2017

The concentration of C14-hydrochlorothiazide was measured in blood, bile, pancreatic juice, and urine collected in suitably prepared dogs for 1 hr after intravenous injection of a dose (27.5 mg) producing consistent diuresis. No appreciable radioactivity appeared in the secretin-stimulated pancreatic juice, but amounts indicating drug concentrations up to 600 µg/ml were found in the bile, similar to levels in the urine. Blood levels were less than 5 µg/ml. Increase in bile flow by intravenous infusion of Bromsulphalein dye solution or by secretin injection did not alter the biliary secretion pattern of hydrochlorothiazide. Thus, drug secretion in bile appeared to be independent of water secretion. Serum, bile, and pancreatic juice were analyzed for rate of flow, specific gravity, pH, Na, K, Cl, and CO2 and bile for cholic acid. Biliary parameters were not altered. Pancreatic secretion showed an increase in volume and in K concentration. CO2 concentration and pH increased if control values of CO2 were less than 130 mEq/liter. Flow and K results could be explained by nonspecific effects also seen in other tissues.
Electrolytes and blood pressure of rats drinking sodium chloride solutions
Authors: Haight Arthur S. , Weller John M.
Published: December 2017

Eighty per cent of rats surviving 8–12 weeks when given 1.75 or 2.0% sodium chloride solution in place of drinking water had at least 20 mm Hg elevation of systolic arterial blood pressure. Changes in tissue water and electrolytes were: a) a consistent increase in sodium, potassium, and chloride contents of aorta; b) an increase in sodium and extracellular water contents of muscle, more marked in skeletal than heart muscle; c) marked muscle potassium depletion in one series; and d) an increase in total body sodium and a tendency toward hypernatremia. At the time of sacrifice no consistent association was evident between blood pressure elevation and water and electrolyte changes.
Pressure-diameter relations of excised aorta
Authors: Remington John W.
Published: December 2017

A length of abdominal aorta was excised, and volume pulses were made at different pressure values by volume injections. The expected diameter changes were calculated from a static stretch curve made from a ring cut from the vessel. External diameter changes were recorded by a transformer coil. The two sets of data could be compared only after calculating the expected changes in wall thickness. Agreement was good enough to conclude that both techniques could measure wall extensibility. When the vessel was elongated to the in situ length, the external diameter showed an appreciable decrease. If wall volume was constant, this could be accounted for by a wall thinning. With such elongation, circumferential extensibility was clearly decreased. The vessel wall was almost isotropic at pressure values above 50 mm Hg, but at lower pressures it showed evidence of an architectural nonhomogeneity in its stretch behavior.
Role of carotid and aortic bodies in mediating the increase in cardiac output during anoxemia
Authors: Penna Mario , Soma Lawrence , Aviado Domingo M.
Published: December 2017

In 14 anesthetized dogs the inhalation of 5% oxygen in nitrogen for 2.5 min caused an increase in cardiac output, measured by the dye dilution technique (16.8% ±6.1 se). After surgical carotid-aortic chemoreceptor denervation, anoxemia still increased cardiac output (27.1% ±6.7 se). An effect of chemoreceptor denervation was the reduction of the control level of cardiac output. In the presence of a similar reduction of cardiac output by bleeding (innervated animal) anoxemia caused a greater increase in cardiac output than in the control preparation. The increase in cardiac output was accompanied by a decrease in total peripheral systemic resistance in the denervated state as compared to an increase in the innervated state. The increase in cardiac output during anoxemia was not prevented by complete spinal anesthesia. A possible cause for the increase in the denervated animal is a combination of the increase in venous return and fall in total systemic peripheral resistance.
Elicitation of theoretically predicted feedback oscillation in arterial pressure
Authors: Sagawa Kiichi , Carrier Oliver , Guyton Arthur C.
Published: December 2017

In a preceding servoanalytic study of the cerebral ischemic pressor response, the authors predicted that, under certain conditions, this emergency mechanism would go into a feedback oscillation and vasomotor waves would appear. The predicted conditions were a) that the cerebral perfusion pressure be as low as 30–10 mm Hg and b) that the time-dependent variable components of the systemic arterial pressure be transferred to the perfusion pressure with the same magnitude. The present experiment was conducted for the purpose of confirming such a theoretical prediction. The transfer of the systemic arterial pressure changes to the cerebral perfusion pressure was accomplished by a special coupling apparatus, and in all of the 11 experiments the cerebral ischemic response mechanism lapsed into feedback oscillation, and intense vasomotor waves were brought about. The period of these waves coincided almost exactly with those predicted by the servoanalysis of the cerebral ischemic response in individual dogs.
Evidence for a humoral factor in vagotomy-induced pulmonary edema
Authors: Rech R. H. , McCarthy L. E. , Borison H. L.
Published: December 2017

Two types of experiments were performed on unanesthetized guinea pigs: a) acute parabiotic union with common peritoneal cavity; and b) continuous cross circulation. Three combinations of animal pairs were employed in each type of experiment, grouped as follows: group 1, both partners were not vagotomized; group 2, both partners were vagotomized; group 3, one partner was vagotomized and its mate was not vagotomized. Lung-to-body weight ratio served as the index of pulmonary edema. In the parabiosis series, the vagotomized partner of group 3 was protected from edema by being joined with a nonvagotomized animal. In the cross-circulation series, the nonvagotomized partner of group 3 developed pulmonary edema as a result of being cross-perfused with a vagotomized animal. In both series, survival time of vagotomized animals was prolonged by their being juxtaposed to nonvagotomized animals. Interaction between vagotomized and nonvagotomized partners in parabiosis as well as in cross-circulation experiments is best explained by exchange of an edemagenic substance.
Behavioral effects of 5-methoxy-N:N-dimethyltryptamine, other tryptamines, and LSD
Authors: Gessner Peter K. , Page Irvine H.
Published: December 2017

The effect of 5-methoxy-N:N-dimethyltryptamine on the conditioned avoidance response of trained rats was compared quantitatively, using a shuttle-box, with that of several substituted tryptamines and LSD-25. 5-Methoxy-N:N-dimethyltryptamine, at a dose level of 19 µm/kg, had a pronounced effect on the conditioned avoidance response, much more pronounced than that due to the known psychotomimetic substituted tryptamines: N:N-dimethyltryptamine, N:N-diethyltryptamine, and 5-hydroxy-N:N-dimethyltryptamine (bufotenine) at the higher dose level of 25 µm/kg. A similar response was elicited by LSD-25 at a dose level of 6 µm/kg. Both hydroxyindole-O-methylase and an enzyme capable of N-methylating indoleethylamines occur in mammals. This circumstance makes it possible to form 5-methoxy-N:N-dimethyltryptamine from such substrates as serotonin. The pronounced behavioral effect of this and similar methoxyindolealkylamine suggests that abnormal tryptophan metabolism could result in mental disturbance.