Specific binding of estradiol to rat coronary artery smooth muscle cells

We report the expression and characteristics of the estrogen receptor in rat coronary artery-derived smooth muscle cells. Polymerase chain reaction analyses of total and poly(A)+ mRNA from rat coronary artery-derived smooth muscle cells indicate the presence of estrogen receptor mRNA. Binding analyses reveal the presence of high affinity binding sites for 17β-estradiol, with a K,equivalent to that observed for authentic estrogen receptors in other estrogen responsive tissues. Scatchard and Hill plot analyses of the properties of receptor-ligand binding indicate the presence of a single site, and the absence of cooperative binding. Unlabeled E2 but not testosterone, dexamethasone or progesterone compete with [³H] 17β-estradiol for binding sites. The affinity, specificity and non-cooperative nature of the estrogen binding sites are identical to those observed in other estrogen-responsive tissues. These cells may provide a novel model in which to study the effects of estrogens on the proliferation, differentiation and function of vascular smooth muscle cells.