AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 5 470-R475, Copyright © 1980 by American Physiological Society
Thermoregulatory ability of female rats during pregnancy and lactation
E. A. Knecht, M. A. Toraason and G. L. Wright
Thermoregulatory ability of female rats was examined before pregnancy,
during gestation, and during lactation. Thermoregulatory pattern, colonic
temperature, evaporative water loss, and survival time were monitored
during terminal heating (39.5 +/- 0.9 degrees C) designed to allow
prolonged survival (3-4 h) with a sustained thermoregulatory effort.
Results confirmed our previously reported observation of decreased
thermoregulatory ability in lactating dams, with evidence suggesting
thermoregulatory impairment during late gestation. Lactating dams displayed
a type III thermoregulatory pattern, and established a rate of evaporative
water loss effective for thermostasis at an elevated colonic temperature.
However, survival time was significantly decreased compared to
nonreproducing females. In contrast, prior heat acclimation tended to
increase the survival time of lactating dams. It was concluded that the
reduction in thermoregulatory ability observed in lactating dams was
related to their inability to maintain a rate of evaporative water loss
effective for thermostasis at an elevated colonic temperature.
