Studies on the mechanism of the central antihypertensive effect of guanabenz and clonidine.

Mean arterial pressure and heart rate responses were measured following intracerebroventricular (i.c.v.) injections of guanabenz and clonidine in conscious intact, sinoaortic baroreceptor denervated (SAD) animals, and in SAD animals with anteroventral third ventricle (AV3V) or sham-AV3V lesions. These results suggest that in the conscious unrestrained rat: (1) the centrally-mediated depressor effect of guanabenz and clonidine is masked by intact baroreceptors; (2) the centrally mediated bradycardia is independent of baroreceptor function and (3) the integrity of the AV3V region is not required for expression of these central effects.