Journal of Applied Physiology, Vol 49, Issue 3 431-437, Copyright © 1980 by American Physiological Society
Body fluid and hematologic adjustments during resting heat acclimation in rhesus monkey
I. R. Oddershede and R. S. Elizondo
The purpose of this study was to examine body fluid adjustments during
prolonged resting heat exposure in primates. Rhesus monkeys were acclimated
for 35 days at 35 degrees C and 30% rh. Red cell mass, extracellular fluid
volume (ECF), and total body water (TBW) were determined with 51Cr, 35SO4,
and 3H2O, respectively, prior to and at intervals during heat exposure.
Heat acclimation was characterized by a fluid shift from the interstitial
compartment. In relation to TBW, interstitial fluid volume and ECF
decreased 10.3 and 8.3%, respectively, while plasma volume (PV) and
intracellular fluid were increased an average of 5.8 and 3.8%. TBW
increased 4.8% during heat exposure. Hematocrit and hemoglobin decreased
significantly on day 3 (7.9 and 6.5%) followed by a return toward control
values. PV in relation to TBW remained elevated throughout the exposure. An
increased drinking (25.0%) was associated with a decrease in caloric intake
(30.7%) during heat acclimation. This study has provided a complete body
fluid compartment analysis during resting heat acclimation in the rhesus
monkey. Our results are consistent with the hypothesis that heat
acclimation in primates is characterized by a protein and fluid shift from
the interstitial fluid compartment to the cardiovascular system and to the
intracellular compartment.
