Acute heat/exercise stress in rats: effects on fluid and electrolyte regulatory hormones

Abstract

Adult, male rats were exercised in the heat until hyperthermic exhaustion ensued. Plasma aldosterone levels were significantly (p less than 0.001) elevated after 8 min of exercise and remained increased throughout the exercise and recovery periods. Alternatively, plasma angiotensin I levels were unaffected during exercise, but increased significantly (p less than 0.001) during the recovery period. These rapid elevations in hormonal levels may be part of a sympathicoadrenal response to heat/exercise stress as well as an adaptational response to maintain plasma volume during and following exercise in the heat.