Angiotensin II-dependent hypertension and the arterial baroreflex.

Angiotensin II (ANG II)-dependent hypertension involves the resetting of the heart rate (HR) and sympathetic baroreflex toward higher pressures in conscious rabbits. The resetting of the HR baroreflex function occurs within minutes of the administration of ANG II, while the resetting of the sympathetic baroreflex requires several days. In conscious rabbits, an intact area postrema (AP) is required for the resetting of either the HR or sympathetic baroreflex function. Data is also presented showing that pretreatment with an alpha-1 adrenergic receptor antagonist prevents the early resetting of the HR baroreflex.