Effect of the vasopressin antagonist d/CH2/5Tyr/Et/VAVP on the antidiuretic action of exogenous and endogenous vasopressin.

The effect of [1-(beta-mercapto-beta, beta- cyclopentamethylene -propionic acid),2-0- ethyltyrosine ,4-valine]-arginine vasopressin on the water metabolism was studied in rats. The compound decreases the antidiuretic action of exogenous vasopressin in Brattleboro rats; in rats without diabetes insipidus it causes temporary polyuria and eliminates the response of antidiuresis to an osmotic stimulus. The results indicate that this compound can block the antidiuretic action of both exogenous and endogenous vasopressin.