Brachial vascular reactivity in blacks

Endothelial function was studied ultrasonographically in a healthy subset o f African Americans (blacks) because they have an increased risk of hyperte nsion and vascular disease. Twenty-four healthy black and 28 well-matched w hite subjects were investigated. Ischemia was induced by inflating a cuff o ver the forearm to 40 mm Hg higher than systolic pressure for 5 minutes. Br achial artery diameter and blood flow velocity were measured at baseline an d at 15, 45, and 60 seconds after deflation by use of an Acuson 128XP10 ult rasonograph with a 7.5 MHz transducer, Mean postischemic dilatation, an ind ex of endothelial function, was 1.76+/-0.56% in blacks and 8.79+/-1.22% in whites (P<0.001). Median postischemic vasodilatation in black men [0% (0% t o 2.86%)] was not significantly different to that in black women [0182% (0% to 3.14%)], whereas white women [11.48% (8.70% to 14.29%)] dilated signifi cantly more than white men [4.20% (2.13% to 5.56%)] (P<0.05). Both groups d ilated significantly over baseline diameter to sublingual nitroglycerin adm inistration 18.7+/-2.5% (blacks) and 20.2+/-3.2% (whites; P=NS), Mean hyper emic responses did not differ significantly between the 2 subject groups, n or did they differ between men and women of both ethnic groups. We;conclude that endothelium-dependent vasodilatation is significantly impaired in hea lthy, young blacks compared with-whites and that gender differences are not seen in blacks with regard to this phenomenon. An impairment in endotheliu m-dependent NO generation may be a contributing factor to future hypertensi on and vascular disease in healthy blacks.