Journal of Applied Physiology, Vol 41, Issue 4 528-531, Copyright © 1976 by American Physiological Society
Lack of humanlike active vasodilation in skin of heat-stressed baboons
C. R. Wyss and L. B. Rowell
To discover whether humanlike active skin vasodilation occurs in a
sweating, subhuman primate, four unanesthetized male baboons (Papio anubis)
were heated (blood temp = 39-39.5 degrees C) before and after arterial
administration of the alpha-adrenergic blocking agent phenoxybenzamine HCl.
Hcat stress alone increased common iliac vascular conductance (CIVC) from
1.2 to 3.7 ml-min-1-mmHg-1 (averages). alpha-Blockade alone increased CIVC
from 1.2 to 3.3 ml-min-1-mmHg-1. Heat stress subsequent to alpha-blockade
further increased CIVC by only 0.4 ml-min-1-mmHg-1. Thus, most of the rise
in CIVC caused by heat stress could be mimicked by alpha-blockade. If, as
in man, the dominant means of raising skin blood flow were nonadrenergic
active vasodilation, the response of CIVC to heating would far exceed that
due to alpha-blockade. We conclude that, in baboons, humanlike active
vasodilation of skin plays no significant role in CIVC response to heat
stress. Thus, the baboon is not an appropriate model for investigation of
control of human skin circulation during hyperthermia.
