Effects of Environmental Heat Stress and Exercise on Renal Blood Flow and Filtration Rate

Abstract

Renal plasma flow and glomerular filtration rate were detd. on 5 normal male subjects at rest and during moderate exercise on the treadmill (3 m.p.h. up a 5% grade) in both a cool (21 [degree]C) and a hot environment (50[degree]C). Na p-aminohippurate and mannitol, respectively, were used for the detns. In the cool environment the mean renal plasma flow of the resting men was 695 cc./min. and it dropped 42% during exercise in the same environment. At rest in the hot environment the mean renal plasma flow was 426 cc./min. Exercise in the heat caused a decrease of 36% from the resting level. In the cool environment the glomerular filtration rate of the men at rest averaged 108 cc./min. and exercise in this environment did not significantly alter it In the heat the avg. filtration rate of the resting subjects fell to 84 cc./min. and when they exercised there was a further decrease to 70 cc./min.