ABSTRACT
Endothelium-dependent hyperpolarization and relaxation to acetylcholine mediated by endothelium-derived hyperpolarizing factor ( E D H F ) are impaired in arteries of spontaneously hypertensive rats (SHR). The studies summarized in this chapter tested: (a) whether or not antihypertensive treatment improves the impaired EDHF-mediated responses in S H R arteries; (b) whether or not there are any differences in the beneficial effects among different classes of antihypertensive drugs (the converting enzyme inhibitor enalapril, the A T ¡-receptor antagonist TCV-116, and a conventional therapy with hydralazine and hydrochlorothiazide); and (c) whether or not the combination of A T r receptor blockade and converting enzyme inhibition exerts additional effects compared with each intervention alone. A l l antihypertensive treatments improved EDHF-mediated hyperpolarization and relaxation in mesenteric arteries from S H R . The improvement achieved with enalapril or TCV-116 tended to be greater than that with a conventional therapy with hydralazine and hydrochlorothiazide. The combination of enalapril and TCV-116 exerted similar effects to those of each intervention, although EDHF-mediated hyperpolarization tended to be greater in the former. These findings suggest that: (a) antihypertensive treatment restores the impaired EDHF-mediated responses in S H R ; (b) blockers of the renin-angiotensin system may be more efficacious in improving endothelial function; and (c) combined A T preceptor blockade and converting enzyme inhibition does not appear to have an additive or synergistic effect.
