The sustained antihypertensive effect of chronic cerebroventricular infusion of angiotensin antagonist in spontaneously hypertensive rats.

The angiotensin antagonist [Sar1-Ile8]angiotensin II was infused into the lateral ventricles of mature spontaneously hypertensive and normotensive Wistar-Kyoto rats. Infusions were maintained at rats of 1200 ng/h for 6 days, and blood pressure was measured daily in the unanesthetized state. Blood pressure reduction occurred promptly and only in the hypertensive animals. This antihypertensive effect persisted for several days after discontinuation of the infusion. In contrast, iv infusion of the angiotensin antagonist at comparable doses failed to alter blood pressure in any significant fashion. These data suggest that the brain isorenin system participates in the maintenance of hypertension in the spontaneously hypertensive rat.