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.

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Age-related increase in the migration of aortic smooth muscle cells induced by 12-L-hydroxy-5,8,10,14-eicosatetranoic acid.

Studies were made on how age influenced the migration of aortic smooth muscle cells. For this, aortic cells from rats of various ages were established in culture in vitro and migration of the cells was measured by the filter membrane technique in modified Boyden chambers. 12-L-Hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), which is mainly produced by platelets and leukocytes and is a strong chemoattractant for rat aortic smooth muscle cells, was used at a concentration of 6 X 10(-15) g/ml in this work. Proliferation of smooth muscle cells decreased significantly with age, but the plating efficiency and cell size did not. In contrast, cell migration induced by 12-HETE showed an age-related increase: The 12-HETE-induced cell migration activities of cells from 6- and 25-month-old rates were 226.7 +/- 35.4 and 223.2 +/- 37.9 cells/10 high-power fields (HPF), respectively, which were significantly higher than that of 121.4 +/- 20.1 cells/10 HPF for cells from 2-month-old rats (P less than 0.05). There was no age-related change in the dose-response curve to 12-HETE for migration of smooth muscle cells. The observed changes are closely associated with the processes of development and maturation of rat aorta.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗