title: Heat acclimation: cardiovascular response to hot/dry and hot/wet heat loads in rats.
abstract: Body temperature, blood pressure (BP) and heart rate (HR) of rats before and after acclimation to heat were studied in chronically cannulated sedentary conscious rats in different hot environmental conditions [hot/dry: 40 degrees C, 20% relative humidity (RH) and hot/wet: 35 degrees C, 70% RH]. During exposure to heat stress, acclimated rats showed an attenuated increase in colonic temperature (Tc) compared to non-acclimated rats. Concomitantly, an abrupt decrease in HR, delayed and attenuated elevation in mean arterial BP and improved cardiac efficiency were recorded. Differences were observed upon exposure to the hot/wet and hot/dry climates: the hot/dry climate imposed a greater physiological burden than the hot/wet climate. The data suggest that for sedentary rats dry heat produces a greater load than humid heat. Thus, the conventional heat load indices do not apply universally but have a thermoregulatory pattern specificity.
authors.affiliation: Heller Institute of Medical Research, Sheba Medical Center, Tel-Hashomer, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Moran
authors.forename: Y
authors.initials: Y
authors.lastname: Shapiro
authors.forename: U
authors.initials: U
authors.lastname: Meiri
authors.forename: A
authors.initials: A
authors.lastname: Laor
authors.forename: M
authors.initials: M
authors.lastname: Horowitz
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects; D006358:Hot Temperature; D006813:Humidity; D008297:Male; D051381:Rats; D013312:Stress, Physiological / Q000503:physiopathology