title: Effects of 17beta-oestradiol on rat isolated coronary and mesenteric artery tone: involvement of nitric oxide.
abstract: Pre- and post-menopausal women receiving oestrogen replacement therapy have a significantly reduced risk of cardiovascular disorders. It has been suggested that this protection might be partly a result of a direct relaxant effect of oestrogens on coronary arteries. This study examines and directly compares the effects of 17beta-oestradiol on rat isolated coronary and mesenteric vessels. The influence of nitric oxide on these responses was also investigated. 17Beta-oestradiol caused similar concentration-dependent relaxation of isolated coronary and mesenteric resistance arteries pre-contracted with either KCl (60 mM) or 9,11-dideoxy-11alpha,9alpha-epoxymethanoprostaglandin (U46619; 1 microM). The relaxation responses to 17beta-oestradiol were significantly reduced, but not totally inhibited, in the presence of N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase; they were not altered by indomethacin, an inhibitor of prostaglandin synthesis. The responses to 17beta-oestradiol in the presence of L-NAME were not dependent on the vessel studied or the pre-contracting agent used. These results suggest that nitric oxide might contribute to the vasodilatory effects of 17beta-oestradiol in rat isolated coronary and mesenteric resistance arteries.
authors.affiliation: Department of Medicine, Manchester Royal Infirmary, UK.
authors.forename: D
authors.initials: D
authors.lastname: Otter
authors.forename: C
authors.initials: C
authors.lastname: Austin
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology*; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D004791:Enzyme Inhibitors; D004965:Estrogen Antagonists; D014662:Vasoconstrictor Agents; D009569:Nitric Oxide; D004958:Estradiol; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester