ADRENAL CORTEX AND WORK IN THE HEAT

Abstract

The effects of extract of adrenal cortex were studied in healthy young 3d on a constant adequate diet and marching 3 1/2 hrs. daily in moist heat. In comparison with the striking influence of water drunk during work the extract had no effect beneficial or otherwise on the subjects'' performance or feelings. The adrenal cortical extract had no consistent effects on the following physiological or chemical functions in the course of marching or during the whole day: heat balance, rate of sweating or skin temp.; respiratory exchange; blood pressure; serum Cl, Na, K or NPN; daily urinary excretion of Na and of Cl. On days when extract was injected, the urinary excretion of K was increased. Suggestive evidence was obtained that the extract lowered the conc. of Cl and Na in the sweat and raised the conc. of K. A previous hypothesis concerning the normal regulation of sweat Cl is extended to sweat Na. Both are present in sweat in almost identical concs. and appear to be correlated with 3 important factors: personal idiosyncrasy; a central factor measured by rectal temp. and rate of sweating; and a peripheral factor associated with skin temp. The general level rises with increasing rectal temp. and rate of sweating. Superimposed on this general level are fluctuations associated with changing local skin temp. K apparently cannot be included in the above hypothesis and is actively secreted by the sweat glands.