Pharmacological effects of urotensins. II. Renal effects of urotensin I in the rat.

Urotensin I decreased urine flow, glomerular filtration rate and renal plasma flow in intact and hypophysectomized rats. The antidiuretic effect of urotensin I differed from the that caused by AVT in that (a) the urine conductivity was not usually increased by the former, and (b) the rates of excretion of Na and K were different. The use of hypophysectomized rats and of Na-thioglycollate-treated urotensin I preparations indicated that the antidiuretic effect of urotensin I was not due to the release of endogenous ADH, nor was it caused by presence of AVT in the urotensin I samples.