Showing papers in "American Journal of Physiology in 1964"
TL;DR: The effect of arterial Pco2 in the control of cerebral hemodynamics over the full range of responsiveness of the cerebral vasculature was studied in the rhesus monkey.
Abstract: The effect of arterial Pco2 in the control of cerebral hemodynamics over the full range of responsiveness of the cerebral vasculature was studied in the rhesus monkey. Cerebral perfusion pressure a...
538 citations
TL;DR: Pressure within the microvascular bed of the frog mesentery has been recorded continuously with micropressure transducers and the waveform of the pressure pulses in arterioles and metarterioles closely resembles that in the larger arteries.
Abstract: Pressure within the microvascular bed of the frog mesentery has been recorded continuously with micropressure transducers which have tip diameters ranging between 0.5–5 µ. The mean values of pressure are in the range of those previously reported. The waveform of the pressure pulses in arterioles and metarterioles closely resembles that in the larger arteries. This observation signifies that the vascular walls are considerably stiffer than is generally believed. The stiffness is probably attributable to the constricted vascular smooth muscle.
432 citations
TL;DR: Unit activity from neurons of hypothalamic feeding and satiety mechanisms, and from adjacent hypothalamic regions, was recorded in anesthetized dogs with surgically exposed hypothalamus, and in Flax...
Abstract: Unit activity from neurons of hypothalamic feeding and satiety mechanisms, and from adjacent hypothalamic regions was recorded in anesthetized dogs with surgically exposed hypothalamus, and in Flax...
401 citations
TL;DR: Samples of proximal and distal tubular fluid were collected from rats maintained on a control, a low-K, or a high- K, low-Na diet and inulin-C14 was administered.
Abstract: Samples of proximal and distal tubular fluid were collected from rats maintained on a control, a low-K, or a high-K, low-Na diet. All animals received inulin-C14. Plasma (P) and tubular fluid (TF) ...
381 citations
TL;DR: Renin concentrations of renal venous plasma were indirectly measured by bio-assaying the pressor activity produced by plasma incubation under standardized conditions by detecting the presence of Na6(CO3)(SO4)2, Na2SO4 and Na2CO3 in the plasma.
Abstract: Renin concentrations of renal venous plasma were indirectly measured by bio-assaying the pressor activity produced by plasma incubation under standardized conditions. Pressor activity was detectabl...
309 citations
TL;DR: Familial hypothalamic diabetes insipidus has arisen as an apparently spontaneous mutation from a strain of Long-Evans hooded rats being bred for unrelated researches not involving radioactivit...
Abstract: Familial hypothalamic diabetes insipidus (DI) has arisen as an apparently spontaneous mutation from a strain of Long-Evans hooded rats being bred for unrelated researches not involving radioactivit...
295 citations
TL;DR: Multilocular brown adipose tissue in the rat is shown to increase in both mass and respiratory rate, in vitro, during cold acclimation, facilitated in part by a "reverse" type of countercurrent heat exchange apparently not previously described.
Abstract: Multilocular brown adipose tissue in the rat is shown to increase in both mass and respiratory rate, in vitro, during cold acclimation. By vascular convection the resulting heat is directly applied to the thoracocervical regions of the spinal cord, the heart, and other thoracic organs. The vasculature is so arranged as to exercise a fine order of thermogenic control over the brown fat and temperature of the peripheral venous returns to the thorax, facilitated in part by a "reverse" type of countercurrent heat exchange apparently not previously described.
280 citations
TL;DR: It is concluded that the gradient in tissue pressure, and hence in the extravascular component of coronary resistance, is at least in part, the cause of the nonhomogeneous blood flow across the wall.
Abstract: Myocardial tissue pressure increases from epicardium to endocardium, and in the deeper layers exceeds ventricular blood pressure during one-third of the cardiac cycle (21). The effect of this tissue pressure gradient on local blood flow was studied using the depot clearance technique. Blood flow was found to be at least 25% lower in the deep regions as compared with superficial ones. With total coronary inflow held constant, vagal arrest of the heart removed the tissue pressure gradient, and simultaneously redistributed flow from superficial to deeper layers. We conclude that the gradient in tissue pressure, and hence in the extravascular component of coronary resistance, is at least in part, the cause of the nonhomogeneous blood flow across the wall. By use of the oxygen cathode, a gradient of oxygen tensions was observed which paralleled the blood flow gradient; mean oxygen tension in the subepicardium averaged twice that in the subendocardium. The gradient in oxygen tension appears to be of sufficient magnitude to determine a transmural gradient in aerobic metabolism.
248 citations
TL;DR: Lung extracts were obtained by either mincing the lungs in saline or by washing the lung with saline through the trachea and no evidence of the presence of sphingomyelin or other surface-active phospholipid was obtained.
Abstract: Lung extracts were obtained by either mincing the lungs in saline or by washing the lung with saline through the trachea. The surface tensions of the extracts on compression to 10% of the original ...
216 citations
TL;DR: The effect of changes in blood flow and of blood oxygen tension on oxygen uptake of the in situ gastrocnemius-plantaris muscle group of the dog was examined and capillary density in contracting muscle was found to be much greater than in resting muscle and was about the same as the capillarydensity measured by others by histological techniques.
Abstract: The effect of changes in blood flow and of blood oxygen tension on oxygen uptake of the in situ gastrocnemius-plantaris muscle group of the dog was examined. Oxygen uptake by resting muscle was not altered by changes in blood flow or blood oxygen tension except when these parameters were reduced below critical values. When the muscle group was contracting once per second, changes in blood oxygen tension were similarly without effect until a critically low value was reached. Although the contracting muscle used eight times as much oxygen per minute as resting muscle, the critical oxygen tension was lower than that for resting muscle. In an attempt to explain this observation the blood-tissue oxygen tension difference was estimated and used in the Krogh equation to calculate capillary density. The capillary density in contracting muscle was found to be much greater than in resting muscle and was about the same as the capillary density measured by others by histological techniques.
212 citations
TL;DR: Traumatized rat omentum was used to demonstrate the development of "platelet plugs" following agitation in platelet-rich plasma, and in the absence of divalent cation there was only platelet adhesion to plasma.
Abstract: Traumatized rat omentum was used to demonstrate the development of "platelet plugs" following agitation in platelet-rich plasma. In the absence of divalent cation there was only platelet adhesion t...
TL;DR: The similarity between the gradient of longitudinal tissue pressure predicted by the theoretical analysis and the gradient experimentally determined suggests that the latter describes the maximum pressures which exist in the left ventricular wall.
Abstract: A new technique for estimating myocardial tissue pressure is described. The method is based upon changes in flow through an analog of a small coronary vessel. A gradient of tissue pressure from epicardium to endocardium was observed with peak tissue pressures twice peak ventricular pressure recorded in the inner half of the wall. A theoretical analysis of the concept of intramyocardial pressure is presented, based on the assumption that the tissue is a solid within which both longitudinal and radial compressive forces exist. The similarity between the gradient of longitudinal tissue pressure predicted by the theoretical analysis and the gradient experimentally determined suggests that the latter describes the maximum pressures which exist in the left ventricular wall.
TL;DR: Isometric force generation, the result of the interaction of an actively shortening contractile element with a passive series elastic component with a Passive Series elastic component, has been analyzed in heart muscle using a diffusion-gauging apparatus.
Abstract: Isometric force generation, the result of the interaction of an actively shortening contractile element (CE) with a passive series elastic component (SE), has been analyzed in heart muscle using th...
TL;DR: Adenohypophysectomized rats were subjected to an avoidance learning procedure and only 6 of 21 rats achieved the conditioning criterion against 14 of 18 sham-operated controls.
Abstract: Adenohypophysectomized rats were subjected to an avoidance learning procedure. Only 6 of 21 adenohypophysectomized rats achieved the conditioning criterion against 14 of 18 sham-operated controls. ...
TL;DR: Pregnant rats fasted on the 18th or 19th day of gestation developed hypoglycemia, severe ketosis, and hyperlipemia, which consisted primarily of triglycerides.
Abstract: Pregnant rats fasted on the 18th or 19th day of gestation developed hypoglycemia, severe ketosis, and hyperlipemia. The latter, which consisted primarily of triglycerides, was accompanied by increa...
TL;DR: Estrogen and thyroxine induction of hepatic hexosemonophosphate shunt and NADP-linked malic dehydrogenases was studied in rats on chow and on a high-fat, low-carbohydrate diet.
Abstract: Estrogen and thyroxine induction of hepatic hexosemonophosphate shunt and NADP-linked malic dehydrogenases was studied in rats on chow and on a high-fat, low-carbohydrate diet. A different enzyme p...
TL;DR: A device was constructed to record continually the oxygen consumption of a dog and to summate as the oxygen deficit the difference between normal oxygen use and oxygen use during hypotension.
Abstract: A device was constructed to record continually the oxygen consumption of a dog and to summate as the oxygen deficit the difference between normal oxygen use and oxygen use during hypotension. Dogs ...
TL;DR: Multiple indicator-dilution studies of the hepatic uptake of sulfobromophthalein in the dog were carried out using a single intraportal injection of labeled red cells, labeled albumin, and sulfobro...
Abstract: Multiple indicator-dilution studies of the hepatic uptake of sulfobromophthalein in the dog were carried out using a single intraportal injection of labeled red cells, labeled albumin, and sulfobro...
TL;DR: The rate of incorporation of palmitate-1-C14 into neutral lipids and phospholipids of rat liver slices in vitro and its conversion to C14O2 were shown to increase markedly as the free fatty acid (F...
Abstract: The rate of incorporation of palmitate-1-C14 into neutral lipids and phospholipids of rat liver slices in vitro and its conversion to C14O2 were shown to increase markedly as the free fatty acid (F...
TL;DR: Digitalis-sensitive Na-K activated ATPase (Na-K ATPase), implicated in active cation transport, was shown to occur in cat choroid plexus.
Abstract: Digitalis-sensitive Na-K activated ATPase (Na-K ATPase), implicated in active cation transport, was shown to occur in cat choroid plexus. Cerebrospinal fluid (CSF) formation rate, measured by colle...
TL;DR: Rats receiving small amounts of cadmium in drinking water exhibited systolic hypertension, the incidence being greater in females than in males, and in males the disorder appeared later in life.
Abstract: Rats receiving small amounts of cadmium in drinking water exhibited systolic hypertension, the incidence being greater in females than in males. In males the disorder appeared later in life. Cadmium-free rats seldom became hypertensive. Rats also exposed to a choice of 1% NaCl solution when young and when old appeared to show more hypertension than those not exposed; females took 65% more cadmium. The hypertension was usually associated with increased mortality and renal vascular changes.
TL;DR: The transfer of glucose, 2-deoxy-d-glucose, and fructose between blood and cerebrospinal fluid of anesthetized dogs was studied following either intravenous injection or intracisternal administering.
Abstract: The transfer of glucose, 2-deoxy-d-glucose, and fructose between blood and cerebrospinal fluid (CSF) of anesthetized dogs was studied, following either intravenous injection or intracisternal admin...
TL;DR: Local cooling of the anterior hypothalamic-preoptic area in rats, at environmental temperatures of 5 and 24 C, caused their rectal temperatures to increase as much as 3.1 C, as well as vigorous shaking of the rectum during sexual activity.
Abstract: Local cooling of the anterior hypothalamic-preoptic area in rats, at environmental temperatures of 5 and 24 C, caused their rectal temperatures to increase as much as 3.1 C, as well as vigorous shi...
TL;DR: The proximal and distal tubular sodium transport systems were studied under conditions of an increased sodium load and the natriuretic and diuretic response to an elevation of the plasma sodium concentration is effected by surpassing a distal Tubular transport maximum for sodium.
Abstract: The proximal and distal tubular sodium transport systems were studied under conditions of an increased sodium load. Fluid was collected by micropuncture from various sites along the nephron of rats receiving a 4% sodium chloride infusion. Samples were analyzed for sodium and inulin-C14, and compared with those obtained from a nondiuretic control group. Inulin clearances were higher in the sodium chloride-loaded rats while their over-all fractional sodium reabsorption was significantly reduced. In animals in which the urinary excretion rate of sodium remained below 12% of the filtered load, fractional sodium and water reabsorption within the proximal tubule were not different from the control group. Under these conditions, no proximal maximal tubular transfer rate for sodium could be observed. Only when urinary excretion rates of sodium exceeded 12% of the filtered load was fractional proximal tubular sodium reabsorption depressed. During sodium chloride loading fractional sodium reabsorption was always reduced in the distal tubule and the collecting duct when compared with the control group. Since this distal tubular transfer capacity does not substantially increase, the natriuretic and diuretic response to an elevation of the plasma sodium concentration is effected by surpassing a distal tubular transport maximum for sodium.
TL;DR: A high incidence of gallstones was observed during a study of the effect on the serum cholesterol of feeding an "atherogenic" diet to aurothioglucose- (ATG) injected obese and nonobese mice.
Abstract: A high incidence of gallstones (90%) was observed during a study of the effect on the serum cholesterol of feeding an "atherogenic" diet to aurothioglucose- (ATG) injected obese and nonobese mice. ...
TL;DR: The intrarenal infusion of kallidin-10 at 1–3 µg/min in the dog produces an increase in directly measured renal blood flow with no alteration in systemic blood pressure, and a diuresis is observed which is associated with substantial increases in sodium and chloride excretion but smaller increases in total solute and potassium excretion.
Abstract: The intrarenal infusion of kallidin-10 at 1–3 µg/min in the dog produces an increase in directly measured renal blood flow with no alteration in systemic blood pressure. Concomitant with the increase in blood flow, a diuresis is observed which is associated with substantial increases in sodium and chloride excretion but smaller increases in total solute and potassium excretion. Neither urinary pH nor free water changed consistently. The pattern of water and electrolyte secretion suggests that the observed changes are secondary to an increase in glomerular filtration rate, although an increase in endogenous creatinine or inulin clearance could not be detected. The contralateral kidney showed no changes during infusion of the decapeptide indicating the rapidity with which it is destroyed in vivo. The renal responses to acetylcholine mimic those produced by kallidin-10. These data, together with earlier observations showing that the kidney excretes both the proteinase, urinary kallikrein, and its hypotensive polypeptides, suggest that this enzyme system may contribute to renal blood flow regulation and to salt and water homeostasis.
TL;DR: By comparison with the radioactive microsphere method, the K42 clearance technique was found to be reasonably accurate for determination of the distribution of the total flow within the organ.
Abstract: Total gastric blood flow in the dog as estimated by the K42 clearance technique agreed within 5% with measured total venous outflow. Extraction of the isotope by the stomach was found to be such that 30–60 sec following injection the organ contained a fraction of the injected dose that was the same as the fraction of the cardiac output that perfused the organ. By comparison with the radioactive microsphere method, the K42 clearance technique was also found to be reasonably accurate for determination of the distribution of the total flow within the organ. Mean total gastric blood flow in intact dogs, unoperated upon except for femoral arterial and venous catheterization, was 49 ml/min per organ or 0.54 ml/min per gram. This was distributed 80% to corpus and 20% to antrum. The corpus flow was partitioned among the mural tissues: mucosa 72%, submucosa 13%, and muscle serosa 15%.
TL;DR: Feeding was consistently associated with a rapid increase in the temperature of the preoptic area, piriform cortex, and abdominal cavity and the activity associated with eating was postulated to account for the increase in brain and other body temperatures.
Abstract: Stainless steel and polyethylene reentrant tubes were implanted permanently in the brain and abdominal cavity of male albino rats. Thermocouples were placed in the tubes and the leads were counterweighted over the rat cage. Temperatures were recorded continuously for up to 4 hr in unanesthetized, unrestrained rats. A decrease in temperature of the preoptic area usually accompanied sleep. Feeding was consistently associated with a rapid increase in the temperature of the preoptic area, piriform cortex, and abdominal cavity. A significant increase in metabolic rate occurred simultaneously with the rise in temperature of the preoptic region. The caloric content of the diet was not important in determining the degree of temperature rise. The activity associated with eating was postulated to account for the increase in brain and other body temperatures.
TL;DR: One microliter of various concentrations of carbachol or norepinephrine was injected via a chronic cannula into the "feeding-drinking" area of the hypothalamus of satiated rats, which elicited less drinking, some lethargy, and then convulsions.
Abstract: One microliter of various concentrations of carbachol or norepinephrine was injected via a chronic cannula into the "feeding-drinking" area of the hypothalamus of satiated rats. Doses of 2.7 throug...
TL;DR: The results indicate that oxygen could well be a factor in the autoregulation of blood flow and that the smaller vessels gave the greatest response to low oxygen.
Abstract: The role of oxygen in control of local blood flow was investigated in isolated arterial segments 1 cm in length and 0.5–1.0 mm in diameter by perfusion with blood of various Po2 levels. A decrease in vascular resistance always occurred when the Po2 was lowered and an increase occurred when it was raised. In 20 vessels, using constant-pressure perfusion, an average increase in conductance of 2.38 times normal level was obtained when the Po2 was lowered from 100 to 30 mm Hg. When this datum was plotted according to initial flow, the smaller vessels gave the greatest response to low oxygen (2.73 times normal; sem ± 0.15), whereas the largest gave the least (1.76 times normal; sem ± 0.10). Forty-three vessels perfused under constant-flow conditions gave results which were consistent with and confirmed the constant-pressure results. In all of these experiments pH, Pco2, and temperature were monitored and kept at physiological levels. The results indicate that oxygen could well be a factor in the autoregulation of blood flow.