Effect of Acute Hyperthermia on Adrenal 17-Hydroxycorticosteroid Secretion in Dogs

¹ From the Naval Medical Research Institute, National Naval Medical Center, Bethesda, Maryland

Effect of acute hyperthermia on adrenocortical function has been studied by measuring 17-hydroxycorticosteroids in adrenal venous blood of anesthetized dogs. Dogs immersed to the shoulders in 50°C water respond initially with a rapid increase in rectal temperature (42°C in 15–20 min.), a marked (two to sevenfold) increase in adrenal corticoid output, and a slight (10–20%) increase in adrenal venous blood flow. When a rectal temperature of 44–45°C was attained, circulatory failure occurred and a concomitant decrease in adrenal corticoid output and venous blood flow ensued. Dogs subjected to a gradual increase in body temperature had increased adrenal 17-hydroxycorticosteroid secretion in the rectal temperature range of 39– 40°C, but this stimulatory response subsided as body temperature was further increased. Hypophysectomy abolished the adrenocortical response to hyperthermia, thus showing that the increased secretory activity of the adrenal cortex in hyperthermia is mediated via the pituitary gland.