alpha-Methylnoradrenaline induced hypotension and bradycardia after administration into the area of the nucleus tractus solitarii.

Bilateral injections of alpha-methylnoradrenaline into the area of the nucleus tractus solitarii of the brain stem caused a dose-dependent decrease of systemic arterial blood pressure and heart rate of anesthetized rats. The effects were prevented and even reversed by a preceding injection of the alpha-adrenoceptor blocking agent phentolamine. Pressor doses of angiotensin II and of arginine-vasopressin at the same site failed to drcrease blood pressure and heart rate.