New evidence for neuronal function of vasopressin: sympathetic mediation of intrathecal vasopressin-induced hypertension

Abstract

Intrathecal injection of arginine vasopressin in rats at a dose as small as 10 ng produced dose-dependent hypertension and tachycardia. Pretreatment with the ganglionic blocking agent Ecolid, alpha-adrenoceptor antagonist phenoxybenzamine or the monoamine depleting agent reserpine blocked this effect without affecting intravenous vasopressin-induced hypertension. Intracerebroventricular injection of arginine vasopressin also induced hypertension and tachycardia, but 600 ng was needed. Ecolid and phenoxybenzamine also abolished this effect. Reserpine was not tested. It is concluded that both intrathecal and intracerebroventricular vasopressin-induced hypertension appears to be mediated by the sympathetic system and that the spinal cord is more sensitive than the supraspinal sites to vasopressin in regulating autonomic functions.