Abstract: Although the general dependence of coronary flow on myocardial qo2 was confirmed in an in situ heart preparation, changes in aortic pressure and cardiac output were observed to be capable of influe...

Abstract: C 14 glucose was adminisered continuously to unanesthetized normal dogs by intravenous infusion following a priming dose at a rate which maintained the specific activity of the circulating glucose at a nearly constant level. Glucagon-free insulin was then administered intravenously in varying doses. Samples of blood were collected at intervals throughout the experiment and more frequently just subsequent to insulin injection. The glucose concentration of the circulating blood and the specific activity of this glucose, when considered together, allow calculations to be made of a ) the outflow of glucose toward the tissue cells, and b ) the inflow of glucose from the liver during the period after insulin injection. By this means it was shown that increased glucose uptake by the tissues is much more important than decreased delivery of glucose by the liver in bringing about insulin-induced hypoglycemia. It was also shown that recovery from hypoglycemia is brought about by increased glucose delivery by the liver and not by a decrease in tissue uptake of glucose below the preinsulin level. Alternative methods of calculation of absolute values for glucose inflow and outflow during periods of changing blood glucose concentrations are discussed and evaluated.

Abstract: A single injection of endotoxin derived from Gram negative bacteria caused an increased survival in lethally irradiated animals when given immediately after or 24 hours before irradiation. Mice responded better to the injection before irradiation and hamsters to the injection after irradiation. The effect was associated with a reduction in infection, very pronounced in the case of α-streptococcus or Proteus and still significant in the case of Pseudomonas infection. No beneficial effect was obtained when mice were given three endotoxin injections during 1 week or six injections during 2 weeks prior to irradiation. The beneficial effect is not necessarily associated with the granulocytosis which begins within a few hours after the endotoxin injection, or with the conditions under which nonirradiated animals show an increased resistance to bacterial challenge.

Abstract: A method is described for the identification of proximal and distal tubules on the surface of the living rat kidney. In 32 anesthetized rats, under control conditions, the hydrostatic pressure in the proximal tubules averaged 12.5 ± 2.2 mm Hg and 6.7 ± 1.6 mm Hg in the distal tubules. During infusion of hypertonic solutions of mannitol, glucose, urea and sodium chloride, the lumina of the proximal and distal tubules dilated and the intratubular pressures and rate of urine flow increased. Also during diuresis, the clear-cut difference between proximal and distal intratubular pressures disappeared and, in general, there was a linear relation between distal intratubular pressure and rate of urine flow. These results are interpreted to mean that the collecting system is a limiting factor in the outflow of urine from the kidney, and is an important determinant of the intratubular pressure, particularly at high rates of urine flow.

Abstract: The nitrogen excretion was studied in the one-humped camel, Camelus dromedarius. When a growing camel was maintained on a low N intake (dates and hay) the amount of N excreted in the form of urea, ...

Abstract: The strength-interval curve of dog ventricular myocardium has been measured with anodal and cathodal stimulation. During diastole the anodal threshold is higher than the cathodal. As anodal stimuli...

Abstract: Ouabain induces a moderate increase in the contractility of the nonfailing heart of the dog with a complete circulatory system in doses which do not produce electrocardiographic signs of digitalis ...

Abstract: Effects of various concentrations of CO2 on brain excitability and electrolyte distribution in rats were studied, and also some properties of seizures induced by abrupt withdrawal from high concent...

Abstract: A preparation consisting of a papillary muscle and attached bundle of Purkinje fibers has been employed to study refractoriness of single cardiac fibers of the dog heart. Transmembrane stimulation ...

Abstract: The preparation of chronic gastric fistula rats, their care and how they may be used for physiological and pharmacological studies on gastric secretion is described. The rat has a large interdigestive secretion and secretes free acid (pH 4.5) after 48–72 hours of fasting. For controlled studies this requires the replacement of fluid and chlorides. Statistically significant differences between the control output of acid and the response to 1 mg of histamine diphosphate were obtained. The threshold dose of the diphosphate is approximately 0.1 for a 350-gm rat. The least amount of histamine diphosphate to yield an average maximum output of acid (10 mg/hr.) is 0.5 mg subcutaneously every 15 minutes. The body dose of histamine required to stimulate gastric secretion is about the same in man, dog, cat and the rat. On the basis of body weight, the amount of histamine base required to yield a maximum output of acid in the rat is 34.6 µg/kg/min. as compared with 1.6 µg/kg/min. in the dog.

Abstract: Spreading depression is accompanied by a slow potential change, a drop in cortical conductivity and by vascular changes. The latter were investigated in histological preparations of cortex frozen while a spreading depression was in progress. In the cat and rabbit a broad wave of vasodilatation was observed. In the rabbit this appeared to be preceded by a narrow region of vasoconstriction. Spreading depression can be changed into spreading convulsive activity by administering CO 2 in the respiratory air (7–12%). CO 2 markedly decreased the drop in cortical conductivity but affected the magnitude of the slow potential change only moderately. It is postulated that both the conductivity drop during spreading depression and a similar drop observed after asphyxiation of the brain are caused by a transport of ions from the intercellular compartment into cortical cellular elements. The relationship between the slow potential change, conductivity drop, vascular changes and the changes in the electrocorticogram during spreading depression is discussed.

Abstract: Electrical stimulation of helically cut strips of rabbit carotid artery, mounted so as to allow development of tension isometrically, causes a contraction-relaxation cycle which remains reproducibl...

Abstract: Sequential changes in the plasma lipids of rats injected with Triton were studied. It was observed that following a dose of Triton, the accumulation of triglyceride (neutral fat), cholesterol and p...

Abstract: By means of a spirally cut strip of rabbit thoracic aorta, it has been shown that angiotonin exists in two forms. One form, angiotonin II, causes a contraction of the strip. The other, angiotonin I, is inactive. They are equally pressor when injected intravenously in animals. An enzyme in plasma converts the inactive form to the active form. The identical pressor activity can be explained by the excess of the converting enzyme in the plasma of the intact animal which rapidly converts angiotonin I to angiotonin II. Some patients with hypertension have a greater content of the converting enzyme in their plasma than is found in plasma of normotensive subjects. In addition to the converting enzyme, other factors in plasma enhance the ability of angiotonin and catechol amines to induce constriction of the strip of aorta. These factors may sensitize the mechanisms in the muscle which set up the process of contraction.

Abstract: The effect of graded degrees of K depletion on the ability to produce a concentrated urine was studied in Sprague-Dawley rats. With increasing degrees of K depletion, as measured by the concentration of K in fat-free skeletal muscle, there was a progrossive decrease in the maximum urinary concentration. This defect of the renal concentrating mechanism appeared to be better correlated with the degree than with the duration of potassium depletion and could be demonstrated either by the use of exogenous vasopressin or by water deprivation. The potassium-deficient rats in at least one experiment developed a significant polydipsia. The data do not allow any conclusions with respect to the relationship of the polydipsia to the renal concentrating defect except that the latter at least was not severe at the onset of the increased water intake.

Abstract: Performance characteristics, stability and ventricular function curves were studied in an isolated heart preparation in which the metabolic state of the perfusing blood was kept at or near normal by continued exchange with a supporting dog. In contrast to the progressive failure exhibited by the classical isolated heart or heart-lung preparations, the isolated supported heart's performance did not differ from the performance of the heart in an open-chest, anesthetized dog with a complete circulation. Myocardial O2 consumption could be determined with a high degree of precision. O2 debt comparable to that which occurs in skeletal muscle was not observed.

Abstract: Observations in the rhesus monkey are described suggesting a close relationship between emotional responses to environmental factors and pituitary-adrenal cortical activity, as judged by plasma and...

Abstract: Pigeons were kept at different air temperatures while measurements were taken of the temperatures in various parts of their bodies. At room temperature the abdomen and the pectoral muscles had nearly the same temperature. At –22°C the pectorals stayed one-half to two degrees warmer than the abdomen, which remained the same as at room temperature. Myograms from the pectorals showed a considerable electrical activity in the cold which vanished at room temperature. It is concluded that the increased pectoral temperature reflects an elevated heat production. As the pectorals of a pigeon make up about one-third of the body weight, it is clear that they make a significant contribution to the accessory heat during cold stress.

Abstract: Longitudinal contractions of the rabbit oviduct do not change in amplitude or rate at different intervals after mating to 4 days, but they become greater in pregnancy and less in pseudopregnancy. Oil and India ink are spread in both directions by segmentation and pendular movement of the smooth muscle but they are arrested at 2–3 cm anterior to the tubo-uterine junction unless more than 0.1 ml is used. Paralysis of the muscle with nicotine prevents movement. When a plastic tube is inserted through the tubo-uterine junction, passage of ova past the critical zone is hastened. Ligature of the infundibular end of the oviduct causes distension, so that oviduct secretions must normally pass through the infundibulum and not into the uterus. This probably aids the transport of spermatazoa while ova are kept from escaping in this direction by the cilia and by the mucosal folds.

Abstract: Cortical electrical resistance increases considerably after cortical asphyxiation. After a latent period of about 3 minutes a sudden resistance change occurs during which one-third of the cortical ...

Abstract: With minute quantities of C14 l-histidine as substrate, rat stomach histidine decarboxylase shows a far higher activity than that from any other mammalian organ tested. Its maximum activity is ph 7...

Abstract: Acute myocardial failure is observed when the denervated heart-lung preparation is rendered acidotic by increasing abruptly above 5% the CO2 concentration in a respiratory gas mixture of CO2 and O2...

Abstract: Progressive uniform cooling of the spinal cord and brain was found to produce a phase of hyperresponsiveness between temperatures of 35°C to 25°C. Below this level all recorded reactions were reduc...

Abstract: The comparative metabolism of calcium and strontium during fetal development was investigated in rats and rabbits using double tracer techniques In general, the placental transfer from dam to fetu

Abstract: Aphagic chickens have been produced with electrolytic lesions placed stereotaxically in the diencephalon. These chickens were maintained by introducing food into their crops through a tube. They were inactive and lost much of the ‘nervous’ temperament of White Leghorn chickens. One or more of these chickens showed additional disturbances: impaired gastrointestinal motility, temperature regulation, adipsia and abnormal body composition.

Abstract: Body and organ weights of sea level control rats were compared with those of rats (P) born at sea level and then exposed to 12,470 feet, and with those of rats (F2) of the second filial generation ...

Abstract: A fluorometric method was used to quantitate plasma epinephrine and norepinephrine during hemorrhagic and anaphylactic shock in healthy adult dogs anesthetized with pentobarbital. Arterial plasma w...

Abstract: Alloxan diabetic rats failed to show the characteristic edema and elevated plasma histamine levels which follow the intravenous injection of dextran or egg white. Pretreatment with insulin restored the ability of these rats to respond in a normal fashion. Insulin in normal rats promotes edema formation and histamine release induced by dextran or egg white. In contrast to these findings, neither diabetes nor insulin pretreatment exerted an influence on the response of rats to intravenously injected compound 48/80. These results suggest a hitherto unrecognized role of insulin in certain types of inflammation and histamine release.

Abstract: In decerebrate and decerebellate cats stimulation of any division of the trigeminal nerve induces efferent volleys in the VIIth, Xth, XIth and XIIth nerves. Direct stimulation of the face, internal nares and dura mater produces similar volleys. In uncurarized animals similar stimuli cause twitches of face and neck muscles. Slowing of the heart rate may also be induced. Conduction times measured in the brainstem and cranial nerves show that conduction is very rapid in the brainstem to the level of the obex, so that large medullated fibers may be inferred. At the level of the obex a delay of 2–4 msec. occurs, presumably due to synapses and internuncial neurones. Conduction of the volleys in the Xth and XIth nerves is rapid and large fibers must be involved. Removal of the dorsal vagal nuclei does not abolish the vagal reflex which is presumed to relay at the nucleus ambiguus. The vagal responses are very easily fatigued.