ROLE OF THE BARORECEPTOR REFLEX IN CENTRAL BLOOD-PRESSURE RESPONSE TO ANGIOTENSIN-II

The effects of an intracerebroventricular (i.c.v.) injection of 10 ng angiotensin II (ANGII) on blood pressure (BP), heart rate (HR) and splanchnic nerve activity (SpNA) was recorded in rats with intact and eliminated baroreceptor reflex (BRR). Under the conditions of an intact BRR the i. c. v. injection of 10 ng ANGII caused a significant increase in BP and decrease in HR and SpNA. In contrast, under the conditions of elimination of the BRR by BP clamping, no changes in HR or SpNA were observed. The results indicate that the reduction of HR and SpNA after stimulation of central ANGII receptors is mediated by a stimulation of the BRR. Our finding that there was no increase in HR or SpNA after elimination of the BRR is consistent with the hypothesis that the central pressor effects of ANGII are not mediated by a generalized stimulation of the peripheral sympathetic nervous system.