IDENTIFICATION OF A CENTRAL SITE OF ACTION OF ANGIOTENSIN II

¹ Department of Pharmacology, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania

The administration of angiotensin II during ventricular perfusion into the cerebral aqueduct of -chloralose-anesthetized cats anterior to the subnucleus medialis produced marked pressor effects, whereas administration of equivalent doses caudal to this nucleus produced significantly lower pressor effects. Bilateral lesions placed in the periaqueductal gray at the level of the subnucleus medialis markedly reduced the pressor responses to intraventricular administration of angiotensin II. Bilateral lesions placed 1 mm caudal to this area in the periaqueductal gray did not significantly alter the pressor response of angiotensin II. The administration of 100 ng of angiotensin into the nucleus mesencephalicus profundus, which is the second synaptic area of the intrinsic pressor pathway had no effect on the cat systemic blood pressure. These data suggest that angiotensin II produces a centrally mediated pressor response in the -chloralose-anesthetized cat via an action on the subnucleus medialis.