Fitness And Body Composition Do Not Affect Racial Differences In Endothelial Function In Postmenopausal Women

Abstract

Endothelial dysfunction is a known predictor of cardiovascular disease (CVD), and may be worsened in the postprandial state, particularly after ingestion of a high-fat meal. In women, postmenopausal status increases the risk of endothelial dysfunction, which tends to be more impaired in African Americans (AA). Low aerobic fitness and obesity are also associated with impaired endothelial function. PURPOSE: We investigated whether fitness and fatness affected endothelial function at rest and after a high-fat meal challenge in AA and Caucasian (C) postmenopausal women matched for age, BMI, % fat and VO2peak. METHODS: We were able to match 8 AA and 8 C (Age= 55.0 + 1.7 vs 57.6 + 5.2 yr; BMI= 30.8 vs 29.3 kg/m2; %fat 43.4 vs 43.2%; VO2peak= 22.1 vs 21.5 ml/kg/min) subject pairs from a larger sample of postmenopausal women enrolled in a training study. Each subject underwent a VO2peak treadmill protocol, % fat assessment by air displacement plethysmography, and brachial artery flow-mediated dilation (FMD) measurements at baseline, and 2 and 4-hours after a high-fat meal (57% FAT, 25% PROT,18% CHO). Percent FMD was quantified by comparing B-mode ultrasound images of the brachial artery at rest and during reactive hyperemia after 5 min of forearm occlusion. RESULTS: Mixed-model ANOVA revealed impaired postprandial FMD in AA. Baseline FMD was similar between AA and C (5.1% + 2.5 vs 4.3% + 3.4, p= 0.197). In contrast, 2h FMD was reduced in AA (3.5%) and increased in C (9.8%) (p<0.001 AA vs C). At 4h, similar FMD values were observed (AA=6.0% + 2.7, C=6.8% + 3.1). CONCLUSIONS: The present data suggest that the postprandial impairment in FMD observed in postmenopausal AA women compared to C is independent of fitness and body composition. Supported by NIH grant RR00847 to the GCRC