Acute effects of 17β-estradiol on femoral veins from adult gonadally intact and ovariectomized female pigs

Our experiments were designed to determine the acute effects of 17beta-estradiol on femoral veins from intact and ovariectomized female pigs. Rings of femoral veins with or without endothelium. were suspended in organ chambers for measurement of isometric force. Concentration-response curves to 17beta-estradiol (10(-9) to 10(-5) M) were obtained in veins contracted with prostaglandin F-2alpha in the absence and presence of inhibitors of either estrogen receptors (ICI-182780; 10(-5) M), nitric oxide synthase [N-G-monomethyl-L-arginine (L-NMMA); 10(-4) M], soluble guanylate cyclase (1-H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; 10(-5) M), or potassium channels (tetraethylammonium; 10(-2) M). Estrogen receptors were identified with the use of Western blotting and immunostaining in veins of both groups. 17beta-Estradiol caused acute endothelium-dependent relaxations in both groups. Relaxations to 17beta-estradiol were inhibited by L-NMMA and 1-H-[1,2,4]oxadiazolo[4,3a]quinoxalin-1-one but not ICI-182780. Tetraethylammonium. inhibited relaxations only in veins with endothelium. from intact females. Results indicate that 17beta-estradiol causes acute endothelium-dependent relaxations in femoral veins. The relative contribution of nitric oxide and K+ channels as mechanisms involved in relaxations to 17beta-estradiol in femoral veins is modulated by ovarian status.