INVOLVEMENT OF URODILANTIN IN INDUCED HYD ROELECTROLYTIC CHANGES IN HUMANS INDUCED BY A 6-DEGREE HEAD-DOWN TILT

On 6 healthy men, we measured: 1/ the effects of 28-day -6 degrees hea d-down tilt on the excretion of urodilatin and 2/ the relationship bet ween urodilatin and urinary fluid or sodium excretion. Aliquots of the pooled 24-h urine output were used Urodilatin increased parallel to u rinary fluid or Na+ at first day of head-down tilt. Positive and stati stically significant linear correlations could be established between urodilatin (and ANP) and urinary volume, or Na+ in five subjects on si x. Urodilatin might participate as one of the several mechanisms of di uresis and natriuresis of first hours of head-down tilt.