Initial response of human thyroid, adrenal cortex, and adrenal medulla to acute cold exposure

Human subjects were exposed nude to a mild cold of 10 to 15 °C for 1 hour in summer. Free catecholamine excretion in the urine increased markedly during cold exposure. The level of plasma cortisol rose slightly but significantly at the end of cold exposure. Plasma PBI did not change significantly. A rise in blood pressure, a decrease in heart rate, a rise in rectal temperature, cold diuresis, and an increase in urinary electrolyte excretion and hemoconcentration were observed as the initial responses to cold exposure. The physiological role played by endocrine glands in these initial responses is discussed. A preliminary experiment of the same type carried out in winter is described, and some differences in the experimental results from those obtained in summer are noted.