Oxidative stress contributes to the reduced basal limb blood flow in estrogen‐deficient postmenopausal women

Abstract

Basal femoral artery blood flow (FemBF) and vascular conductance (FemVC) are reduced in estrogen-deficient postmenopausal vs. premenopausal women. The underlying mechanisms are unknown, but oxidative stress could be involved. To determine this, 9 premenopausal (23±1 years [mean±SE]; PRE) and 20 estrogen-deficient postmenopausal (55±1; POST) healthy women were studied. During baseline control, oxidized LDL, a marker of oxidative stress, was 50% greater in POST (P<0.001), and FemBF (duplex ultrasound) was 30% lower in POST because of a 36% lower FemVC (P<0.0001); mean arterial pressure (MAP) was not different. Intravenous administration of a supra-physiological dose of the antioxidant vitamin C increased FemBF by 16% in POST because of a 16% increase in FemVC (both P<0.001), but did not affect FemBF in PRE or MAP in either group. In the pooled subjects, the change in FemBF and FemVC with vitamin C were related to baseline plasma oxidized LDL (r=0.45 and 0.51, P<0.005), total body fat (r=0.48, P<0.005) and waist-to-hip ratio (r=0.44 P<0.01). Oxidative stress may contribute to reduced basal FemBF in estrogen-deficient postmenopausal women via chronic vasoconstriction related to increased total and abdominal adiposity. Supported by NIH AG20683, AG22241, AG13038, RR00051.