ETHNIC-DIFFERENCES IN FOREARM VASODILATOR CAPACITY

Previous studies have demonstrated significant ethnic differences in l eft ventricular structure in both normotensive and hypertensive subjec ts. To determine if these differences in ventricular geometry are asso ciated with differences in vascular structure, we measured the minimum forearm vascular resistance in 30 healthy young African-American adul ts and in 30 whites matched for age, gender, and blood pressure. Avera ge daytime blood pressure was determined by ambulatory monitoring duri ng a typical work day. Minimum forearm vascular resistance was measure d by plethysmography after 10 minutes of forearm ischemia. Indexed lef t ventricular mass and relative wall thickness were measured by 2-dime nsional-directed M-mode echocardiography, The mean (+/- SD) ambulatory blood pressure was 126 +/- 11/79 +/- 8 mm Hg in African-Americans and 126 +/- 11/79 +/- 7 mm Hg in whites, The 2 groups were similar in bod y mass index and in family history of hypertension. African-Americans had a higher minimum forearm vascular resistance than did whites (2.39 +/- 0.75 vs 2.03 +/- 0.55 mm Hg, p < 0.05). There was a trend toward a greater left ventricular relative wall thickness in African-American s (0.38 +/- 0.07 vs 0.35 +/- 0.06, p = 0.09), These results suggest th at early vascular remodeling is present in African-Americans who do no t have established hypertension, and that this ethnic difference in va scular structure is associated with a difference in ventricular geomet ry.