Journal of Applied Physiology, Vol 43, Issue 4 739-746, Copyright © 1977 by American Physiological Society
Renal vascular response to heat stress in baboons--role of renin-angiotensin
M. M. Eisman and L. B. Rowell
To determine if hyperthermia in the baboon caused a reduction of renal
blood flow (RBF) similar to that reported in man, we repeatedly exposed six
unanesthetized male baboons (Papio cynocephalus) to ambient temperatures of
42.5-49.0 degrees C for 55-175 min. Internal temperatures rose 1.0-2.0
degrees C. On the average, RBF fell 23.7% per degrees C, renal vascular
resistance (RVR) rose 34.0% per degrees C, and mean arterial pressure (MAP)
fell by only 2.9 Torr. Plasma renin activity (PRA), measured in four
baboons, rose 97.5% per degrees C. To investigate the role of the
renin-angiotensin system in this renal response, we infused propranolol or
saralasin (1-sar-8-ala-angiotensin II), an angiotensin II antagonist,
systemically in 14 experiments on three baboons. Both propranolol and
saralasin infusions prevented most of the reduction in RBF during
hyperthermia. Propranolol prevented the increase in PRA. We conclude that
renal vasoconstriction accompanies moderate hyperthermia in the awake
baboon, and much of this response is mediated by a beta-adrenergic release
of renin.
