CENTRAL MECHANISM OF VASOPRESSIN‐INDUCED CHANGES IN ANTIDIURETIC HORMONE RELEASE

Abstract

1 Intracerebroventricularly (i.c.v.) administered vasopressin (0.001–1.0 u) in dogs anaesthetized with chloralose produced a dose-dependent increase in urine flow with a concomitant decrease in the levels of antidiuretic hormone (ADH) in jugular vein blood. 2 Higher doses of vasopressin (1.5–2.0 u, i.c.v.) on the other hand had an antidiuretic effect and produced an increase in blood ADH level. 3 Pretreatment (i.c.v.) with a β-adrenoceptor antagonist completely blocked the diuretic response of low doses of vasopressin (i.c.v.) but did not influence the antidiuretic response obtained with high doses. 4 Repeated administration of vasopressin (1.0 u, i.c.v.) induced tachyphylaxis; central catecholamine depletion with tetrabenazine significantly inhibited the vasopressin-induced diuretic response. 5 It is concluded that intracerebroventricular vasopressin-induced changes in ADH secretion are mediated through the release of catecholamines in the central nervous system.