Clonidine-induced increase of renal prostaglandin activity and water diuresis in conscious dogs.

I.v. administration of clonidine to conscious dogs induces a water diuresis with hyposmotic urine and minor effect on electrolyte excretion. The diuresis is preceded by an increased urinary PGE excretion, but no change of urinary ADH output is observed. Plasma renin activity decreases. Both ADH infusion and indomethacin pretreatment inhibit the diuretic effect of clonidine. The results support the hypothesis that clonidine-induced water diuresis is mediated via an anti ADH effect due to increased renal prostaglandin activity. Moreover the results suggest that there is no direct stimulation of renin release by PGE.