title: Estradiol-binding sites in rat aortic smooth muscle cells in culture.
abstract: To determine whether aortic smooth muscle cells possess estradiol receptors or not, an estradiol binding study has been performed in cultured rat aortic smooth muscle cells by using an intact-cell assay. Specific binding for estradiol is shown by the cells, and the binding reaches a plateau after 15 min of incubation at 37 degrees C. The binding curve shows a saturable binding process. Scatchard analysis reveals a single population for estradiol binding with a dissociation constant of 5.0 X 10(-8) M and specific binding sites of 64 fmole per 10(6) cells (38,500 sites per cell). Molecular specificity shows highly specific binding with estradiol. Among various steroids tested, only testosterone at 10(-5) M competes slightly (9.3%) with the estradiol-specific binding. These data indicate the existence of specific, high-affinity and limited-capacity binding sites for estradiol in rat aortic smooth muscle cells. This accords with the concept that estrogen responsiveness in aortic smooth muscle cells is mediated through the estrogen-receptor binding in the cells.
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology*; D001665:Binding Sites; D002417:Cattle; D002478:Cells, Cultured; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D006854:Hydrocortisone / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology*; D011247:Pregnancy; D011374:Progesterone / Q000378:metabolism; D051381:Rats; D013739:Testosterone / Q000378:metabolism; D013997:Time Factors
chemical_list: D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D006854:Hydrocortisone