Abstract

BACKGROUND
Although estrogen supplementation can reduce cardiovascular events in postmenopausal women, but the mechanism that mediate this beneficial effect is unclear. Thus, we investigated the acute effect of HRT on endothelial dependent vasodilation using high resolution ultrasound in healthy and diabetic postmenopausal women. METHOD: We examined endogenous (flow dependent dilatation affer 5min cuff occlusion) and exogenous (sublingual nitroglycerin) nitric oxide mediated vasodilation in the brachial artery before and after estrogen supplementation (Premarin R 0.625 mg for 1 wk) in 16 postmenopausal women, and in 18 age-matched postmenopausal women with type 2 diabetes mellitus. RESULTS: There were no differences in age, total & LDL cholesterol level, and body mass index between the groups (p>0.05). However, HDL cholesterol level was significantly lower in patient with diabetes than in normal women (1.0+/-0.3 mmol/L in diabetes and 1.4+/-0.2 mmol/L in normal, p<0.05). Basal endothelium dependent vascular reactivity was significantly attenuated in patient with diabetes when compaired with normal subjects (8.0+/-3,9% versus 13.7+/-6.2%, p<0.05). An estrogen supplementation increased endothelium dependent vasodilation not only in patient with diabetes(from 8.0+/-3.9% to 15.1+/-4.0%, p<0.05), but also in normal women (from 13.7+/-6.2% to 20.1+/-4.7%, p<0.05). Moreover the percent increase of vascular reactivity was higher in patient with diabetes(p<0,05), In contrast, the responses to sublingual nitroglycerin were comparable in diabetes (from 21.1+/-6.0% to 22.1+/-4.1%, p>0.05), and in normal women (from 25.8+/-7.8% to 25.2+/-4.5%, p>0.05) before and after estrogen supplementation. CONCLUSION: Endothelial dysfunction was prominent in patient with diabetes and it was significantly attenuated by estrogen. These results suggest that estrogen replacement improves endothelial dependent vasodilation in healthy and diabetic postmenopausal women.

• Keywords: Nitric oxide;endothelium;Vascular reactivity;Type 2 diabetes mellitus;