Prevention of hyponatraemia and cerebral oedema by the vasopressin antagonist d/CH2/5Tyr/Et/VAVP in rats treated with pitressin tannate.

A rat model of the Schwartz-Bartter syndrome was created by the administration of a high dose of a long-acting vasopressin preparation (pitressin tannate ) together with a forced water intake. The treatment led to water retention, hypernatriuria , marked hyponatraemia (in 4-5 days) and severe cerebral oedema. These changes could be prevented by the simultaneous administration of [1-(beta-mercapto-beta, beta- cyclopentamethylene -propionic acid),2-0- ethyltyrosine ,4-valine]arginine vasopressin. The observations indicate that this vasopressin antagonist analogue might be of use in the future as an effective drug against the Schwartz-Bartter syndrome.