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Effect of Thermal Acclimation on Blood Pressure and Stress-induced Elevation of Core Temperature in Spontaneously Hypertensive Rats and Wistar Rats

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Title: Effect of Thermal Acclimation on Blood Pressure and Stress-induced Elevation of Core Temperature in Spontaneously Hypertensive Rats and Wistar Rats
Authors: Tsuchiya, Katsuhiko / Kosaka, Mitsuo
Issue Date: 30-Jun-1992
Publisher: 長崎大学熱帯医学研究所 / Institute of Tropical Medicine, Nagasaki University
Citation: 熱帯医学 Tropical medicine 34(2). p77-89, 1992
Abstract: Male adult rats of the three strains, spontaneously hypertensive rats (SHR), Wistar-Kyoto rats (WKY) and Wistar rats (WIS) were used. Rats of each strain, at 1 month old, were randomly divided into three groups and chronically exposed to 3 different temperatures, 10℃, 30℃ and 22-24℃. Systolic blood pressure (BP) measured by the tailcuff method and stress-induced elevation of core temperature were compared. In cold-acclimated WKY and WIS, BP was significantly higher than that in the heat-acclimated rat. In SHR, genetically hypertensive rats, there was no significant difference in BP between cold- and heat-acclimated young adult rats, and BP in heat-acclimated older adult rats was higher than that in cold-acclimated SHR. In normotensive rats, WKY and WIS, thermal acclimation affected systemic BP. In normotensive strains, WKY and WIS, cold-acclimation increased BP, whereas heat-acclimation decreased BP. Mean body weights in cold-acclimated rats were greater than those of heat-acclimated ones in all strains except for older adult WKY. For restraint stress, the conscious rat was paced in a loosely fitting small cage. Cold acclimated SHR (SHR-C) and WKY (WKY-C) were restrained at 10℃ and heat-acclimated SHR (SHR-H) and WKY (WKY-H) were restrained at 30℃. At the start of restraint, there was no significant difference among the rectal temperatures of these four groups. During the restraint stress, elevated core temperature was sustained and tail skin temperature decreased. Both values of rectal temperature (Tre) at the 30th min and increase of Tre (dTre) in the first 30th min during the restraint stress were in the order SHR-C>SHR-H>WKY-C>WKY-H. Values of Tre and dTre in cold-acclimated SHR were significantly greater than those in cold-acclimated WKY, and those values in heat-acclimated SHR were significantly greater than those in heat-acclimated WKY. Thermal acclimation, which started in one month old rats, scarcely affected development of hypertension in SHR, whereas thermal acclimation produced a significant difference between BPs in cold- and heat-acclimated normotensive strains of rats. As for the influence of thermal acclimation on the responsiveness of stress-induced elavation of core temperature to the restraint stress, the strain difference was greater than the influence of thermal acclimation.
URI: http://hdl.handle.net/10069/4599
ISSN: 03855643
Type: Departmental Bulletin Paper
Appears in Collections:Volume 34, No. 2

Citable URI : http://hdl.handle.net/10069/4599

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