A comparison of angiotensin-converting enzyme inhibitors, calcium antagonists, beta-blockers and diuretic agents on reactive hyperemia in patients with essential hypertension: A multicenter study

OBJECTIVES The purpose of this study was to compare the effect of different antihypertensive agents, calcium antagonists, angiotensin-converting enzym e (ACE) inhibitors, beta-blockers and diuretic agents on endothelial functi on. BACKGROUND Endothelial dysfunction is a component of essential hypertension , and various antihypertensive drugs may be able to restore normal function . METHODS Forearm blood flow (FBF) was measured in 296 patients with essentia l hypertension, including 46 untreated subjects using strain-gauge plethysm ography during reactive hyperemia and after sublingual administration of ni troglycerin (NTG). Forty-seven normotensive subjects were similarly evaluat ed as control subjects. RESULTS The FBF during reactive hyperemia in the 296 hypertensive patients was significantly less than that in age-matched normotensive subjects. The increase in FBF after administration of sublingual NTG was similar in both groups. Systolic and diastolic blood pressures and forearm vascular resista nce were greater in the untreated group than in the four treated groups and did not differ with respect to the antihypertensive agent used. The maxima l FBF response from reactive hyperemia was significantly greater in the ACE inhibitor-treated group than in the group treated with calcium antagonists , beta-blockers, diuretic agents, or nothing (40.5 +/- 5.2 vs. 32.9 +/- 5.8 , 34.0 +/- 5.6, 32.1 +/- 5.9, and 31.9 +/- 5.8 ml/min per 100 ml tissue, p < 0.05, respectively). Reactive hyperemia was similar in the calcium antago nist, beta-blocker, diuretic and untreated groups, and changes in FBF after sublingual NTG administration were similar in all groups. The infusion of N-G-monomethyl-L-arginine, a nitric oxide (NO) synthase inhibitor, abolishe d the enhancement of reactive hyperemia in hypertensive patients treated wi th ACE inhibitors. CONCLUSIONS These findings suggest that ACE inhibitors augment reactive hyp eremia, an index of endothelium-dependent vasorelaxation, in patients with essential hypertension. This augmentation may be due to increases in NO. (J Am Coll Cardiol 2000;35:284-91) (C) 2000 by the American College of Cardio logy.