title: Estrogen potentiates vasopressin-induced contraction of female rat aorta by enhancing cyclooxygenase-2 and thromboxane function.
abstract: To determine the roles of estrogen and constrictor prostanoids in vasopressin (VP)-induced contraction of female rat aorta, vascular reactivity to VP was determined in thoracic aortas of intact, ovariectomized, and ovariectomized + estrogen-replaced female rats in the presence of indomethacin (Indo), NS-398, SQ-29,548, or vehicle control. The effects of estrogen on vascular reactivity to the thromboxane A(2) analog U-46619 were also examined. Maximal contractile response to VP in intact female rats (5,567 +/- 276 mg/mg of aortic ring wt) was markedly attenuated by ovariectomy (2,485 +/- 394 mg; P < 0.001) and restored by estrogen replacement with 17beta-estradiol (5,059 +/- 194 mg; P > 0.1). Indo and NS-398 significantly attenuated maximal responses to VP in intact female rats to a similar extent [3,176 +/- 179 (P < 0.0001) and 3,258 +/- 152 mg (P < 0.0001), respectively]. Ovariectomy abolished and estrogen replacement restored the inhibitory effects of Indo, NS-398, and SQ-29,548. Contractile responses of rat aorta to U-46619 were significantly greater (P < 0.0001) in females (5,040 +/- 238 mg) than in males (3,679 +/- 96 mg). Ovariectomy markedly attenuated (3,923 +/- 84 mg; P < 0.01) and estrogen replacement restored (5,024 +/- 155 mg; P > 0.1) responses to U-46619 in female aortas. These data reveal that estrogen is an important regulator of the contractile responses of female rat aorta to VP, which appears to potentiate both cyclooxygenase-2 and constrictor prostanoid function in the vascular wall.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Texas A and M University, College Station, Texas 77843, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: John N
authors.initials: JN
authors.lastname: Stallone
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D001127:Arginine Vasopressin / Q000494:pharmacology*; D051546:Cyclooxygenase 2; D004357:Drug Synergism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D010052:Ovariectomy; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D013928:Thromboxane A2 / Q000031:analogs & derivatives* / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D014662:Vasoconstrictor Agents; D001127:Arginine Vasopressin; D004958:Estradiol; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases