PLASMA ATRIAL-NATRIURETIC-FACTOR DURING COLD-INDUCED DIURESIS

The purpose of this study was to evaluate the possible contribution of atrial natriuretic factor (ANF) to cold-induced diuresis. Seven healt hy men, dressed in shorts, were exposed to a cold environment (+12-deg rees-C) for 90 min, and also to a thermoneutral environment. Exposure to cold increased urine output and sodium excretion significantly but plasma ANF concentration remained unchanged. The increase in urinary p otassium excretion during cold exposure was not significant (P=0.0636) and plasma renin activity did not change either. Exposure to cold inc reased mean arterial pressure significantly but it did not affect hear t rate. We concluded that acute exposure to the cold environment induc ed a diuretic response, which was a solute diuresis in its nature. Our results did not give support to the hypothesis that ANF might be invo lved in the renal response to cold exposure.