[Involvement of urodilatin in the hydro-electrolytic modifications induced in man by a 6 degree head-down tilt].

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