ACE inhibition and pressor responsiveness to norepinephrine in hypertensive patients

The pressor response to norepinephrine (NE) was assessed in normal renin essential hypertensive patients before and after they were randomly assigned to receive in parallel groups of treatment a single dose of an angiotensin converting enzyme (ACE) inhibitor (captopril or lisinopril) or a prolonged therapy with lisinopril (30-45 days) or with hydrochlorothiazide (9 days). Blood pressure was significantly reduced by all treatments. The pressor response to NE was unchanged after the single administration of the ACE inhibitors, while it was blunted after chronic administration of lisinopril and after the diuretic. On the basis of these results, it is suggested that the attenuation of the sympathetically mediated vasoconstriction may represent an additional mechanism contributing to the antihypertensive effect of ACE inhibitors administered chronically.