Endothelium-dependent vasodilatation in treated and untreated hypertensivesubjects

It has repeatedly been shown that endothelium-dependent vasodilatation (EDV ) is impaired in patients with untreated hypertension. The effect of antihy pertensive treatment on EDV has, however, not been extensively investigated . In the present study, EDV and endothelium-independent vasodilatation (EID V) were studied in 20 untreated and 41 treated hypertensive subjects and in 26 matched, normotensive controls by means of infusion of methacholine (MC h), 2 and 4 mu g/min, evaluating EDV, and nitroprusside (SNP), 5 and 10 mu g/min, evaluating EIDV, in the brachial artery. Forearm blood flow (FBF) wa s measured by venous occlusion plethysmography. The vasodilatory action of MCh was impaired in untreated hypertensives compared with controls, with th e response in the treated hypertensives in between the other two groups (p < 0.01 vs both of the other groups). EIDV, on the other hand, was enhanced in the treated hypertensives (p < 0.01), so that the MCh to SNP FBF ratio, an index of endothelial function, was attenuated in both treated and untrea ted hypertensives (0.97 +/- 0.24 and 0.96 +/-. 0.15, respectively), compare d with controls (1.27 +/- 0.29, p < 0.001). Both EDV and EIDV declined with increasing number of antihypertensive drugs used in the treated hypertensi ves (p < 0.05). In conclusion, the endothelial function index was found to be similarly depressed in both treated and untreated hypertensive subjects compared with normotensive controls. Antihypertensive therapy seems to impr ove the vasodilatory capacity in general rather than enhancing endothelial function.