title: Effects of acute and chronic estrogenic treatment on vasomotor responses of aortic rings from ovariectomized rats.
abstract: The effects of either chronic or acute estrogenic treatment on the "in vitro" vasomotor responses to phenylephrine (10(-9)-10(-5) M) and to carbachol (10(-9)-10(-5) M) of aortic rings excised from ovariectomized rats were analyzed. Chronic estrogenic treatment consisted in a single subcutaneous dose of 1 mumol estradiol 17-stearate. Effects of acute estrogenic treatment were evaluated by recording the responses of aortic rings excised from untreated ovariectomized rats both before and after the addition of 17 beta-estradiol to the superfusing solutions. In order to identify the endothelium-dependent responses each experiment was performed simultaneously on pairs of rings from the same aorta, one with and the other without functional endothelium. The contractile responses to phenylephrine of endothelium-intact vessels were attenuated by chronic estrogenic treatment; this attenuation was further increased by preincubation of the vessels with indomethacin and was reverted by N omega-nitro-L-arginine methyl ester. Either chronic or acute estrogenic treatment enhanced the carbachol-induced endothelium dependent relaxation of phenylephrine-precontracted rings. The results may be explained by assuming that estrogens increase the basal release of both nitric oxide and a cyclooxygenase-dependent vasoconstricting prostanoid as well as the receptor-mediated release of nitric oxide from the endothelium of the rat aorta.
authors.affiliation: Department of Physiology, School of Medicine, U.N.A.M., Mexico D.F., Mexico.
authors.forename: M C
authors.initials: MC
authors.lastname: Paredes-Carbajal
authors.forename: M A
authors.initials: MA
authors.lastname: Juárez-Oropeza
authors.forename: C M
authors.initials: CM
authors.lastname: Ortíz-Mendoza
authors.forename: D
authors.initials: D
authors.lastname: Mascher
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D002217:Carbachol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D010052:Ovariectomy; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D010656:Phenylephrine; D004958:Estradiol; D002217:Carbachol