Black women (BLW) have a higher incidence of cardiovascular disease (CVD) morbidity and mortality compared to white women (WHW). Vascular dysfunction is a non-traditional risk factor for CVD and BLW demonstrate impaired vascular function when compared to WHW throughout the lifespan. Several previous studies assessed macrovascular and microvascular function in young BLW compared to WHW, but there has been no recent work exploring this disparity in young women using current, up-to-date methodologies. Therefore, the purpose of this study was to evaluate both macrovascular and microvascularfunction as assessed by haemodynamic responses to flow-mediated dilatation (FMD), following current FMD guidelines, in young adult BLW and WHW. We hypothesized that BLW would demonstrate attenuated macrovascular and microvascular responses to FMD compared to WHW. Macrovascular function was assessed as the percentage dilatation of the brachial artery following FMD occlusion-cuff release (FMD%). Microvascular function was assessed by total reactive hyper-aemia area under the curve (RH-AUC), calculated as the cumulative increase in brachial artery blood flow above baseline following FMD occlusion-cuff release. Participants were tested in the morning hours during the early follicular phase of their menstrual cycle. Twenty-eight young, apparently healthy women completed the study: 17 WHW (23 ± 4years) and 11 BLW (24 ± 5 years). FMD% was lower in BLW (WHW: 8.0 ± 1.6, BLW: 6.2 ± 2.4%; P = 0.02), but significance was abolished when FM D% was normalized for shear (WHW: 0.1230 ± 0.0388, BLW: 0.1132 ± 0.0405; P = 0.53). RH-AUC was lower in BLW (WHW: 438 ± 133, BLW: 268 ± 66 ml/min; P < 0.001). Young, otherwise healthy BLW demonstrated impaired microvascularfunction compared to WHW.
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