Acute dilatation to phytoestrogens and estrogen receptor subtypes expression in small arteries from women with coronary heart disease

We tested if endothelial function and estrogen receptor (ER) expression differs between resistance arteries in subcutaneous circulation from postmenopausal women with coronary heart disease (CHD, ≅1 year after myocardial infarction, n = 12) and aged matched controls (n = 14); and if acute effects of phytoestrogens (genistein, resveratrol) could be of relevance for vascular protection. We utilized ex vivo small artery (≅350 μm) bioassays and found no difference in bradykinin (BK)-mediated dilatation between the groups. One-hour incubation with phytoestrogens (natural ERβ agonists), propyl-pyrazole-triol-trisphenol (PPT-selective ERα agonist) and 17β-estradiol (17β-E2-ERα/β agonist) at 0.01 μM/L had no effect on BK-induced responses.Concentration–response curves (0.01–30 μM/L) to investigated compounds were also obtained and compared in separate arteries. We found that dilatation to phytoestrogens was enhanced in CHD if compared to controls (p < 0.05), while responses to 17β-E2 remained similar. The dilatation to phytoestrogens was also higher if compared to 17β-E2 (p < 0.05) in CHD. In controls, only responses to PPT, but not to phytoestrogens, were enhanced in comparison to 17β-E2 (p < 0.05). Inhibition of NO synthase had no effect on dilatation induced by increasing concentrations of investigated compounds. ERβ expression was enhanced in the vascular wall from CHD women, while ERα predominated in the controls (p < 0.05). We suggest that diet supplementation by phytoestrogens may provide cardiovascular benefit for postmenopausal women with CHD. The selective targeting of one of the ER subtype may have implications for women's cardiovascular health.