Effect of potassium depletion on response to acute heat exposure in unacclimatized man

Abstract

The response to environmental heat stress (T 115/91 F, D. B. [dry bulb] to W. B. [wet bulb]) was studied in 4 men resting quietly in a heat chamber before and after depletion of 230-465 meq of potassium (K). Changes in pH, pCO2, aldosterone excretion, serum electrolytes, creatinine, P, and uric acid were determined during the heat exposures. In 3 subjects no change occurred in response to heat stress after K depletion, but in a 4th rectal temperature rose more rapidly. The observed increase in serum concentrations of K, creatinine, and uric acid with heat exposure was not due to reduced renal excretion. After K depletion, biochemical changes were similar except serum K did not increase during heat. The augmented aldosterone excretion during the initial heat stress was blunted after K depletion, although renal Na retention occurred under both circumstances. Release of cellular K, creatinine, and purines may reflect altered metabolic activity during heat, and hyperkalemia may induce production of aldosterone during heat exposure.