Showing papers in "Journal of Applied Physiology in 1971"
TL;DR: Varying numbers of microspheres were injected into the left atrium and ventricles of lambs, sheep, and dogs, and microsphere concentrations were measured in samples drawn simultaneously from two or more arteries (femoral, carotid, or aorta), in the free walls of the left and right ventricle and both kidneys.
Abstract: BUCKBERG, GERALD D., JOHN C. LUCK, D. BRUCE PAYNE, JULIEN I. E. HOFFMAN, JOSEPH P. ARCHIE, AND DAVID E. FIXLER. Some sources of error in measuring regional blood flow with radioactive microspheres. J. Appl. Physiol. 3 l(4) : 538-604. 197 1 .-Radioactive microspheres (8-50 p diameter) distribute in proportion to regional blood flow so that their concentrations in all arteries should be similar but for random variation. Varying numbers of microspheres were injected into the left atrium and ventricles of lambs, sheep, and dogs, and microsphere concentrations were measured in samples drawn simultaneously from two or more arteries (femoral, carotid, or aorta), in the free walls of the left and right ventricles and both kidneys. Coronary and renal blood flows were measured with microspheres (using peripheral reference samples) and by independent methods. Despite some nonrandomness (poor mixing) errors were usually under 20% for all injection and sampling sites in both species as long as each sample had over 400 microspheres; lesser numbers caused errors up to 1 13y0. Variability was less in dogs than sheep, less for left atria1 injections, but equivalent in all arteries. Coronary and renal flows by microspheres were usually within 20y0 and 6%, respectively, of measured flow. The greatest precision occurs on injection of the largest number of microspheres consistent with no physiological changes.
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TL;DR: Human sweating regulation at rest, evaluating thermal inputs effects on thermoregulatory center and internal hypothalamic and skin temperatures is evaluated.
Abstract: Human sweating regulation at rest, evaluating thermal inputs effects on thermoregulatory center and internal hypothalamic and skin temperatures
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TL;DR: It was confirmed that both local and total sweating are functions of internal temperature at a fixed constant mean skin temperature and in the presence of a constant central drive for sweating, the sweating response could be modified at the periphery according to the area-specific characteristics and/or by local temperature.
Abstract: Three subjects performed from 15 to 20 bouts of 10-min bicycle ergometer exercise in a 26 C ambient. The procedure imposed a consistent pattern of internal (esophageal) temperature increase in the presence of a constant mean skin temperature. Body weight loss was continuously recorded and rate of evaporative loss due to sweating was calculated during each minute of exercise. It was confirmed that both local and total sweating are functions of internal temperature at a fixed constant mean skin temperature. In the presence of a constant central drive for sweating, the sweating response could be modified at the periphery according to the area-specific characteristics and/or by local temperature.
TL;DR: Human body temperature regulation under various hydration regimes during exercise, noting changes related to sweating.
Abstract: Human body temperature regulation under various hydration regimes during exercise, noting changes related to sweating
TL;DR: The results show significant reduction in sweat sodium concentration with acclimatization over a wide range of sweat rates, and possible mechanisms are discussed.
Abstract: : Experiments were undertaken to clarify the effects of heat acclimatization on the sodium concentration of sweat and to distinguish these from the effects of concomitant changes in sweat rate. Sweat samples were collected at different rates of sweating from three unacclimatized subjects, using a Perspex capsule containing filter papers. The subjects were then acclimatized to heat, using a passive hyperthermia technique, and a further series of sweat samples obtained at different rates of sweating. The weighed samples were analyzed for sodium concentration and the results used to plot sodium concentration against sweat rate before and after acclimatization. The results show significant reduction in sweat sodium concentration with acclimatization over a wide range of sweat rates. Possible mechanisms are discussed. (Author)