Endothelium‐Dependent Dilation is Greater in Habitually Exercising Postmenopausal Women and is Related to Reduced Vascular Oxidative Stress

Endothelium‐dependent dilation (EDD) is reduced in sedentary healthy postmenopausal compared with premenopausal women. Older men who perform habitual aerobic exercise demonstrate greater EDD than their sedentary peers, but the effects of exercise on EDD with aging in females is unknown. To determine this, EDD (brachial artery flow‐mediated dilation) was measured at baseline and after acute intravenous infusion of the antioxidant ascorbic acid (AA) in sedentary premenopausal (n=10, 24±1 years [mean±SE]; Pre‐S) and postmenopausal (n=12, 56±1; Post‐S), and endurance exercise‐trained postmenopausal (n=10, 60±1; Post‐T) women. EDD was 50% lower in Post‐S vs. Pre‐S (4.6±0.6 vs 9.1±0.7%, P<0.0001), but was greater in Post‐T (6.9±0.7%) than in Post‐S (P<0.01). AA improved EDD in PostS (to 6.8±1.1%, P>0.2 vs. Pre‐S & Post‐T), but had no effect in the other groups. Post‐S had 20% lower (P<0.005) total antioxidant status (TAS) vs. Pre‐S, and higher plasma oxidized LDL vs. Pre‐S and Post‐T (both P<0.05). TAS and oxidized LDL were not different in Pre‐S vs. Post‐T. In the pooled group, baseline EDD was positively related to TAS (r=0.42, P=0.02), and inversely related to oxidized LDL and endothelial cell nitrotyrosine protein expression (r= −0.35 and −0.44, P<0.05), markers of oxidative stress. These results indicate oxidative stress contributes to impaired EDD in Post‐S. Habitual endurance exercise is associated with enhanced EDD in postmenopausal women, possibly by preventing the development of vascular oxidative stress. Supported by NIH AG20683, AG22241, AG13038, AG06537, RR00051.