| Budget Amount *help |
¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1984: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
Increased sweating activity by heat acclimation has been attributed to enhanced central heat-dissipating activity and to augmented secretory capacity of sweat glands, but their relative contributions have been a subject of controversy. The purpose of the present project was to analyze effects of various types of acclimation procedures on the relative importance of those mechanisms, by the use of rate of sweat expulsions ( <F_(sw)> ) as an indicator of central sudomotor activity. The following 9-day acclimation procedures, consisting of daily 90-min controlled hyperthermia with rectal temperature clamped at approximately 38゜C (except for d)), were imposed on four male subjects, respectively: a) heating with dry air ( <H_D> ); b) heating in a humid condition ( <H_W> ); c) exercise in a mildly cool environment (W); d) heating of the body with dry air, except the head which was cooled by face fanning ( <H_D> -F), by which tympanic temperature ( <T_(ty)> ) was clamped at 37.1+0.1゜C while me
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an skin temperature was maintained between 38 and 40 ゜C; and e) exercise with face fanning (W-F), by which <T_(ty)> was clamped at 37.1+0.1゜C. Sweat tests before and after the procedure consited of measurements of local sweat rates, whole body sweat rate ( <E_(sw)> ), <T_(re)> , <T_(ty)> , and skin temperatures, and calculations of <F_(sw)> and mean body temperature ( <T_b> ). Sweating capacity was substantially increased after <H_D> , <H_W> and W in most of cases. The regression line relating <F_(sw)> to <T_b> shifted to the left with those three procedures, while that relating <E_(sw)> to <F_(sw)> tended to increse in slope in case of <H_D> and <H_W> , but showed no change in case of W. On the other hand, no or only slight increase in sweating capacity was noted after <H_D> -F or W-F. The results indicate that enhanced sweating activity by heat acclimation is predominantly attributed to increased central heat-dissipating activity with lowered threshold temperature, at least in an early stage of acclimation by repetitive mild hyperthermia. It is assumed that peripheral adaptive changes develop only gradually unless cutaneous heating is severe. Furthermore, the results with the procedures with face cooling suggest that <T_(ty)> reflects brain temperature, a rise of which greatly influences development of heat acclimation. Less
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