title: Different role of endothelium/nitric oxide in 17beta-estradiol- and progesterone-induced relaxation in rat arteries.
abstract: The present study was aimed to examine the different role of endothelium/nitric oxide in relaxation induced by two female sex hormones, 17beta-estradiol and progesterone in rat isolated aortas and mesenteric arteries. The isometric force of each ring was measured with Grass force-displacement transducers in the organ bathes. 17beta-Estradiol induced both endothelium-dependent and -independent relaxation in the rat aortas but only the endothelium-independent relaxation in the rat mesenteric arteries. In contrast. progesterone induced both endothelium-dependent and -independent relaxation in the rat mesenteric arteries but only endothelium-independent relaxation in rat aortas. N(G)-Nitro-L-arginine methyl ester and methylene blue attenuated the relaxant response to 17beta-estradiol in the aortic rings or to progesterone in the mesenteric arteries. Pretreatment with L-arginine antagonized the effect of N(G)-nitro-L-arginine methyl ester on sex hormone-induced relaxation. The endothelium contribution to relaxation seems to only relate to lower concentrations of 17beta-estradiol and progesterone. In summary, the present results clearly demonstrate a different role of the functional endothelium in the relaxant response to 17beta-estradiol or progesterone in the conduit vessel (aorta) and the resistance vessels (mesenteric artery). Nitric oxide contributes largely to the endothelium-dependent relaxation induced by 17beta-estradiol in the isolated aortas or by progesterone in the mesenteric arteries.
authors.affiliation: Department of Physiology, Chinese University of Hong Kong, People's Republic of China.
authors.forename: H Y
authors.initials: HY
authors.lastname: Chan
authors.forename: X
authors.initials: X
authors.lastname: Yao
authors.forename: S Y
authors.initials: SY
authors.lastname: Tsang
authors.forename: F L
authors.initials: FL
authors.lastname: Chan
authors.forename: C W
authors.initials: CW
authors.lastname: Lau
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology*; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects
chemical_list: D009569:Nitric Oxide; D011374:Progesterone; D004958:Estradiol