Effect of the vasopressin antagonist d(CH2)5 Tyr(Et)VAVP on diuresis in rat.

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 rat. The compound was found to be able to block the antidiuretic action of both exogenous and endogenous vasopressin. A rat model of the Schwartz-Bartter syndrome was created by the administration of a high dose of a posterior pituitary preparation (Pitressin tannate ) together with a forced water intake. The antagonist prevented water retention and averted the enhanced natriuresis and hyponatraemia, and cerebral oedema did not develop. The observations suggest that this vasopressin antagonist might be of use in the future as an effective drug against the Schwartz-Bartter syndrome.