title: Plasma aldosterone and sweat sodium concentrations after exercise and heat acclimation.
abstract: This investigation was designed to determine the relationship between the levels of plasma aldosterone and eccrine sweat gland sodium excretion following exercise and heat acclimation. Ten subjects exercised at 45% of their maximal O2 uptake in a hot (40 degrees C), moderately humid (45% relative humidity) environment for 2 h/day on ten consecutive days. Acclimation was verified by significant reductions in exercise heart rate, rectal temperature, and heat storage, as well as significant elevation of resting plasma volume (12%, P less than 0.05) and exercise sweat rate on day 10 compared with day 1 of acclimation. During exercise, the concentration and total content of sodium in sweat as well as plasma aldosterone were significantly decreased from day 1 to day 10. The ratio of sweat sodium reabsorbed to plasma aldosterone concentration was significantly increased from day 1 to day 10 after both 1 and 2 h of exercise. These data indicate that plasma aldosterone concentrations decrease following heat acclimation; and eccrine gland responsiveness to aldosterone, as represented by sweat sodium reabsorption, may be augumented through exercise and heat acclimation.
mesh_terms: D000064:Acclimatization; D000328:Adult; D000450:Aldosterone / Q000097:blood*; D004439:Eccrine Glands / Q000502:physiology; D004702:Endocrine Glands / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D005082:Physical Exertion; D012964:Sodium / Q000378:metabolism*; D013542:Sweat / Q000378:metabolism
chemical_list: D000450:Aldosterone; D012964:Sodium