Showing papers in "American Journal of Physiology in 1959"
TL;DR: A method is described for studying transcapillary diffusion of K42 in isolated perfused muscles of dogs and its effects on blood flow and arteriovenous K42 differences are measured.
Abstract: A method is described for studying transcapillary diffusion of K42 in isolated perfused muscles of dogs. Blood flow and arteriovenous K42 differences are measured and blood-tissue clearance calcula...
695 citations
TL;DR: Morphological features of blood capillaries from various vertebrate forms and organs are presented and it is suggested that these varying capillary structural features may be relevant to problems relating to exchange of materials between blood plasma and parenchymal cells.
Abstract: Morphological features of blood capillaries from various vertebrate forms and organs are presented. Simple classifications are proposed, based on presence or absence of continuous basement membrane, on the nature of the endothelial cell and on the presence or absence of a complete investment of pericapillary cells. It is suggested that these varying capillary structural features may be relevant to problems relating to exchange of materials between blood plasma and parenchymal cells. Simple three-digit notation systems are presented for characterizing and designating the type of any capillary with respect to the classifications submitted.
588 citations
TL;DR: The osmolality was determined of fluid collected by micropuncture from proximal and distal convolutions, loops of Henle, collecting ducts and vasa recta of kidneys of rodents with and without osmotic diuresis, consistent with the hypothesis that the mammalian nephron functions as a countercurrent multiplier system.
Abstract: The osmolality was determined of fluid collected by micropuncture from proximal and distal convolutions, loops of Henle, collecting ducts and vasa recta of kidneys of various rodents with and without osmotic diuresis. Proximal tubular fluid was isosmotic; in the presence of antidiuretic hormone, early distal fluid was hypo-osmotic due to the prior reabsorption of sodium chloride, and late distal fluid again isosmotic. The hyperosmotic concentration of the urine is established in the collecting ducts, apparently as a consequence, in part at least, of the hyperosmotic reabsorption of sodium chloride in the loops of Henle. Fluid from the bends of loops of Henle, and from collecting ducts and vasa recta at the same level were equally hyperosmotic, consistent with the hypothesis that the mammalian nephron functions as a countercurrent multiplier system. The vasa recta are believed to play an important role in the concentration of the urine by functioning as countercurrent diffusion exchangers.
507 citations
TL;DR: Everted gut-sacs prepared from segments of the proximal small intestine of young rabbits, rats and guinea pigs transport Ca45 in vitro from the mucosal to the serosal surfaces against concentration...
Abstract: Everted gut-sacs prepared from segments of the proximal small intestine of young rabbits, rats and guinea pigs transport Ca45 in vitro from the mucosal to the serosal surfaces against concentration...
294 citations
TL;DR: Procaine (0.025–0.1%; pH 7.9) caused a reduction in the amount and rate of development of the early transient and late steady state currents which occur during a depolarizing voltage step applied to the excised, voltage clamped squid axon.
Abstract: Procaine (0.025–0.1%; pH 7.9) caused a reduction in the amount and rate of development of the early transient (sodium) and late steady state (potassium) currents which occur during a depolarizing voltage step applied to the excised, voltage clamped squid axon. Consistent results were obtained by holding the membrane potential at a hyperpolarized value prior to the applied step. No effect was seen on the resting potential, on the sodium equilibrium potential, or on the proportion of the sodium carrying system which was ‘inactive’ at any membrane potential. The blocking action of procaine is a result of the inhibition by the drug of the sodium carrying system. The effect of procaine on the potassium conductance is such as to oppose the blocking action.
266 citations
TL;DR: The superior olivary nucleus of barbiturate anesthetized cats was explored with microelectrodes and slow wave and single unit activity was recorded to clicks, tones and noise delivered to the two cats.
Abstract: The superior olivary nucleus of barbiturate anesthetized cats was explored with microelectrodes. Both slow wave and single unit activity was recorded to clicks, tones and noise delivered to the two...
265 citations
TL;DR: It has been found that if the suction electrode is properly used the monophasic potentials recorded with it may be taken as a reliable index of the time of arrival of excitation at the electrode and as the shape of the action potential during the entire phase of repolarization.
Abstract: The action potentials recorded from heart muscle with a suction electrode have been compared to those recorded with an intracellular microelectrode. It has been found that if the suction electrode ...
249 citations
TL;DR: Up to 60% of i.v. injected doses of 1-C 14 palmitic acid was found in the liver 15 minutes after injection, two thirds in the form of triglycerides and the rest as phospholipids and the activity in the triglyceride fraction fell rapidly, only 50% remaining after 1 hour, while at the same time theospholipid activity increased.
Abstract: Up to 60% of i.v. injected doses of 1-C14 palmitic acid was found in the liver 15 minutes after injection, two thirds in the form of triglycerides and the rest as phospholipids. Almost no radioacti...
236 citations
TL;DR: The addition of dl-carnitine to various types of particulate liver preparations resulted in augmented oxidation of labeled palmitate and stearate, and carnitine exerted little if any effec...
Abstract: The addition of dl-carnitine to various types of particulate liver preparations resulted in augmented oxidation of labeled palmitate and stearate. In contrast, carnitine exerted little if any effec...
223 citations
TL;DR: There was a significant decrease in total peripheral resistance in anemia and a marked rise in polycythemia, and the maximum number of red cells present for oxygen transport to the tissues was near the mean normal hematocrit of 40.
Abstract: Normovolemic anemia and polycythemia were studied in 14 dogs. Cardiac outputs increased with anemia and fell with rises in hematocrit. Although many factors—such as chemical changes—may play an important role in these variations in cardiac output, there was an indication that viscosity alone may have a major effect. There was no significant association between changes in cardiac output and the various pressures—mean arterial, mean right atrial, mean pulmonary and mean circulatory. Although the pressures did not change significantly, there was a significant decrease in total peripheral resistance in anemia and a marked rise in polycythemia. It was also found that the maximum number of red cells present for oxygen transport to the tissues was near the mean normal hematocrit of 40.
222 citations
TL;DR: 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 tissues.
Abstract: 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...
TL;DR: Intracellular microelectrodes have been used to study the site of origin and direction of spread of activity in the rabbit atrium and a number of fiber groups have been found which posse...
Abstract: Intracellular microelectrodes have been used to study the site of origin and direction of spread of activity in the rabbit atrium. In this study a number of fiber groups have been found which posse...
TL;DR: Temperature was diminished in a stepwise fashion in the isolated kidney of the dog perfused from a peripheral artery of the original, normothermic animal, and hypothermia exerted a marked but reversible depression of the rate of oxidative metabolism.
Abstract: Temperature was diminished in a stepwise fashion in the isolated kidney of the dog perfused from a peripheral artery of the original, normothermic animal. Decreased temperature resulted in an appre...
TL;DR: Diastolic and systolic dimensions of the left ventricle and the free wall of the right ventricles in intact dogs are affected little by spontaneous exercise, and the concept that stroke volume and heart volume are connected is challenged.
Abstract: Diastolic and systolic dimensions of the left ventricle and the free wall of the right ventricle in intact dogs are affected little by spontaneous exercise. The concept that stroke volume and heart...
TL;DR: Normal young adult male rats were either force-fed or allowed to eat ad libitum a moderate carbohydrate diet for 3–4 weeks, and the amount of diet consumed by the animals changed with age.
Abstract: Normal young adult male rats were either force-fed or allowed to eat ad libitum a moderate carbohydrate diet for 3–4 weeks. The force-fed animals were given either the amount of diet consumed by th...
TL;DR: In this article, the effects of long-term fasting were investigated in birds and it was shown that the daily injection of 60 −70 u of either regular or HGF-free insulin per kilogram body weight resulted in an hyperglycemic rebound 24 hours after each injection.
Abstract: Prolonged fasting caused a rise in blood glucose which reached a maximum above the prefast level on the 6th day. Concurrently the liver glycogen, rapidly depleted at the start of the fast, was partially replaced. Blood NPN increased continuously. Thus, gluconeogenesis appeared likely not only to be responsible for the blood glucose increase but also to play a role in the restoration of liver glycogen after initial glycogenolysis due to fasting. Fasting for 48 hours increased cardiac glycogen up to three times the prefasting level; a rapid decrease in this moiety occurred with further abstinence. Glucagon and growth hormone increased the cardiac glycogen of nonfasted birds; but had little, if any, influence on the effects of fasting. The daily injection of 60–70 u of either regular or HGF-free insulin per kilogram body weight resulted in an hyperglycemic rebound 24 hours after each injection. This rebound could be blocked completely by feeding Dibenzyline.
TL;DR: Intravenous glucose tolerance tests were made on male Sprague-Dawley rats, raised on different diets and two natural diets (McCollum's wheat-casein ration and table scraps) produced glucose removal.
Abstract: Intravenous glucose tolerance tests were made on male Sprague-Dawley rats, raised on different diets. Two natural diets (McCollum's wheat-casein ration and table scraps) produced glucose removal ra...
TL;DR: It is suggested that the hyperpolarization produced by insulin is the cause of the potassium shift and the increase in intracellular K is probably too small and too late to account for the hyperPolarization on the basis of conventional theory.
Abstract: Insulin increased resting membrane potential of excised rat muscle, extensor digitorum longus, by about 5 mv in less than 1 hour. In 1 hour insulin caused no increase in the ratio of intra- to extracellular potassium, but in 2–3 hours intracellular K increased by about 10%. It is concluded that the increase in intracellular K is probably too small and too late to account for the hyperpolarization on the basis of conventional theory and it is suggested that the hyperpolarization produced by insulin is the cause of the potassium shift.
TL;DR: Giving the extract of a protein-free bovine pineal extract to intact animals caused effects varying with the dose, which reversed changes in ovarian hypertrophy, pituitary hyperTrophy, and adrenalhypertrophy.
Abstract: Fifty-four 26-day-old female rats of the CD strain were divided into four groups of 10 or 11 each, i.e. 1) controls; 2) animals given 0.3 ml of a protein-free bovine pineal extract daily intraperitoneally for 28 days; 3) sham-operated animals; 4) pinealectomized animals. In a second experiment two groups of six each were divided into a ) control animals given a diet restricted with respect to Na, K and phosphate, and b) animals on the same diet, given 1.0 ml/day of the pineal extract. Pinealectomy caused ovarian hypertrophy ( P < .001), pituitary hypertrophy ( P < .001), and adrenal hypertrophy ( P < .05). The extract reversed these changes. Giving the extract to intact animals caused effects varying with the dose. The dose of 0.3 ml given daily caused gonadal atrophy ( P < .05), pituitary atrophy ( P < .001) and insignificant adrenal activity. The dose of 1.0 ml caused further gonadal atrophy ( P < .001) and significant adrenal atrophy ( P < .05).
TL;DR: In perfused vascular beds the flow properties of blood are essentially linear in the physiological working range so that the distensibility of the vessels is the all important factor in determining the shape of the pressure-flow curves.
Abstract: The role of the non-Newtonian behavior of blood in perfused vascular beds has been assessed by measuring the pressure-flow curves of erythrocyte suspensions with hematocrits from 9 to 85%, in glass tubes of radii from 50 to 800 µ. The curves become linear as the flow increases, and for each tube, point back to a ‘nodal point’ on the negative flow axis which is independent of hematocrit. From this data, curves of the rate of shear versus shearing stress at the wall (consistency curves) were obtained which are all linear at stresses greater than 20 dynes/cm. The wall shearing stress in all categories of blood vessels is greater than this, especially in the arterioles where it is 200 dynes/cm. It is concluded that in perfused vascular beds the flow properties of blood are essentially linear in the physiological working range so that the distensibility of the vessels is the all important factor in determining the shape of the pressure-flow curves.
TL;DR: Utilization of injected urea and urea transfer from blood to rumen were investigated and it was found that injecting urea intravenously into mature sheep receiving a low-pr...
Abstract: Utilization of injected urea and urea transfer from blood to rumen were investigated. First, urea (ca. 5 mmole urea-N/kg body weight) was injected intravenously into mature sheep receiving a low-pr...
TL;DR: Ratios of tissue to plasma radioactivity reached at equilibrium were used to calculate the amounts of plasma proteins present extravascularly, and significant differences between the various plasma proteins were found only in the liver, spleen and stomach.
Abstract: Rates at which plasma proteins penetrate from the vascular system into extravascular spaces in tissues was measured with I131-labeled rabbit gamma globulin, rat gamma and beta globulins, and rat albumin. After vascular mixing was complete, as measured with Cr51-labeled erythrocytes, initial rates of increase in the ratio of tissue radioactivity to plasma radioactivity were used to calculate vascular-extravascular transfer rates; these are reported as grams blood plasma equivalents which penetrate the vascular-extravascular barrier in 1 gm tissue each hour. Transfer rates ranged from 0.06–0.76 for visceral organs to 0.0005–0.005 for tissues such as muscle, fat and skin; the transfer rates were roughly proportional to the vascularity of the tissues. Ratios of tissue to plasma radioactivity reached at equilibrium were used to calculate the amounts of plasma proteins present extravascularly. These protein masses ranged from 0.02 gm plasma equivalents per gm tissue for muscle to 0.13 for skin. Significant differences between the various plasma proteins were found only in the liver, spleen and stomach.
TL;DR: Findings suggest an effect of insulin on protein metabolism independent of its action in promoting glucose entry, which leads to an increase in C14-amino acid incorporation into muscle protein in the absence of glucose in the medium.
Abstract: The effect of glucose concentration and insulin on protein synthesis was investigated using the isolated rat diaphragm and C14-labeled amino acids. When the donor rat has been well fed, the incorporation of histidine-2-C14, lysine-2-C14, phenylalanine-3-C14, and alanine-1-C14 into muscle protein is uninfluenced by glucose concentration in the medium over the range 0–600 mg %. Insulin leads to an increase in C14-amino acid incorporation into muscle protein in the absence of glucose in the medium. This positive effect of insulin in the absence of added glucose is still observed when the diaphragms are pre-incubated for 2 hours prior to adding insulin. These findings suggest an effect of insulin on protein metabolism independent of its action in promoting glucose entry.
TL;DR: Stopped flow microperfusion technique (Am. J. Physiol. 195: 563, 1958) was used to study water movement across the proximal tubular wall of Necturus kidney.
Abstract: Stopped flow microperfusion technique (Am. J. Physiol. 195: 563, 1958) was used to study water movement across the proximal tubular wall of Necturus kidney. In 23 experiments, net water movement wa...
TL;DR: A method was devised which made it possible to depolarize ventricular muscle, over a short interval of length, by applying an external voltage and to record, from the same segment, the developed depolarization process.
Abstract: A method was devised which made it possible to depolarize ventricular muscle, over a short interval of length, by applying an external voltage and to record, from the same segment, the developed te...
TL;DR: Ovariectomized white rats were treated with estradiol benzoate daily for 5 days, and in certain areas the fibers showed pacemaker-like characteristics, i.e. slow membrane depolarization between action potentials.
Abstract: Ovariectomized white rats were treated as follows: group 1, 6.0 µg estradiol benzoate daily for 5 days; group 2, 6.0 µg estradiol for 3 days, then 1.6 µg estradiol plus 12 mg progesterone for 5 day...
TL;DR: A reduction of the renal water requirement in the urea-fed rats was most marked when the ratio in urine between urea and nonurea solutes had a value of 0.3–0.5.
Abstract: Rats allowed water ad libitum were injected with vasopressin tannate in oil to insure formation of maximally concentrated urine. Low protein diet was fed to which were added varying amounts of sodium chloride with or without urea. Through a wide range of urinary excretion rates of nonurea solute the feeding of urea resulted in formation of lesser volumes of more highly concentrated urine. This reduction of the renal water requirement in the urea-fed rats was most marked when the ratio in urine between urea and nonurea solutes had a value of 0.3–0.5. When present in urine in amounts equal to or greater than osmoles of nonurea solute, urea increased the renal water requirement.
TL;DR: A new method has been devised for measuring the compliance (volume change ÷ pressure change) of the pulmonary arterial tree (down to the capillaries), in isolated, Krebs-Ringer-perfused rabbit lungs, assuming a system with lumped compliance, inertance and resistance.
Abstract: A new method has been devised for measuring the compliance (volume change ÷ pressure change) of the pulmonary arterial tree (down to the capillaries), in isolated, Krebs-Ringer-perfused rabbit lungs. The lungs were suspended in a plethysmograph and inflated with N2O. Fluid was introduced into the pulmonary artery by a motor driven syringe and the volume injected was recorded. The capillary flow was deduced from the plethysmograph pressure change which resulted from N2O uptake. Vascular volume change equaled arterial inflow minus outflow into capillaries. The compliance of the venous tree was similarly measured by retrograde perfusion. Mean compliance of the pulmonary arterial tree was 0.17 (S.E. 0.02) ml/cm H2O in six rabbits, mean weight, 4.4 kg. Mean compliance of the pulmonary venous tree was 0.41 (S.E. 0.03) ml/cm H2O in five rabbits, mean weight, 4.3 kg. Compliance of the whole bed (not including the left atrium) was 0.69 (S.E. 0.06) ml/ cm H2O in six rabbits, mean weight, 4.4 kg. Equations were derived relating the length, diameter and number of vessels in the vascular bed. From these the inertance of the blood in the pulmonary arterial tree was estimated to be 8 gm cm–4 in rabbit lungs and 1 gm cm–4 in human lungs. The flow response to sinusoidal pressure waves of different frequencies was calculated, assuming a system with lumped compliance, inertance and resistance. The input impedance of the pulmonary vascular bed, in the rabbit and in man, was minimum for a frequency midway between the fundamental frequency and the second harmonic of the resting heart rate.
TL;DR: In dogs with cardiovascular reflexes completely blocked by total spinal anesthesia, the total peripheral resistance was increased five- or more fold in two ways: first, by injecting small plastic m...
Abstract: In dogs with cardiovascular reflexes completely blocked by total spinal anesthesia, the total peripheral resistance was increased five- or more fold in two ways: first, by injecting small plastic m...
TL;DR: The movements of water and solutes across the ureter and bladder have been studied under conditions approximating those routinely used in physiological experiments at low urine flows.
Abstract: The movements of water and solutes across the ureter and bladder have been studied under conditions approximating those routinely used in physiological experiments at low urine flows. When the uret...