CLONIDINE IMPROVES CENTRAL ATTENUATION OF THE BAROREFLEX IN SPONTANEOUSLY HYPERTENSIVE RATS

To determine whether clonidine can improve the central alteration of t he baroreflex in SHR, the centrally cut end of the aortic depressor ne rve was electrically stimulated in SHR with intravenously administered clonidine. Aortic depressor nerve (ADN) stimulation elicited depresso r and sympatho-inhibitory responses in a frequency-dependent manner in WKY and SHR. These responses were significantly smaller in SHR than i n WKY. The attenuated depressor and sympatho-inhibitory responses to A DN stimulation in SHR were restored following i.v. injections of cloni dine, although the drug did not affect the responses to ADN stimulatio ns in WKY. These findings suggest that clonidine can improve central a ttenuation of the baroreflex in hypertension.