DIFFERENTIAL RESPONSE IN CELL-PROLIFERATION TO BETA-ESTRADIOL IN CORONARY ARTERIAL VASCULAR SMOOTH-MUSCLE CELLS OBTAINED FROM MATURE FEMALEVERSUS MALE ANIMALS

Although the cardioprotective effect of estrogen is well recognized, t he mechanisms by which this sex steroid provides a reduction in corona ry artery disease are not fully understood. Vascular smooth muscle cel ls (VSMC) are present in early atherosclerosis and become the dominant cell type. VSMC contain estrogen receptors and may have specific resp onses to estrogen. We studied the effect of beta-estradiol on the prol iferation of coronary VSMC obtained from sexually mature male, female, and oophorectomized pigs. Alpha-estradiol, an inactive isomer of estr adiol, had no effect on cells obtained from male or female animals. In vascular smooth muscle cells obtained from sexually mature female ani mals, significant inhibition of proliferation of coronary vascular smo oth muscle cells was noted at physiologic concentrations of beta-estra diol, Progesterone inhibited VSMC proliferation at concentrations of 1 0(-9)M. In contrast, beta-estradiol did not alter proliferation in por cine coronary vascular smooth muscle cells obtained from sexually matu re male or from oophorectomized female animals. This study is the firs t to indicate, in an animal model, specific gender-related differences in cell proliferation in response to sex steroid hormones.