Effects of estrogen on nitric oxide biosynthesis and vasorelaxant activity in sheep uterine and renal arteries in vitro.
OBJECTIVE
Our purpose was to determine whether estrogen alters the relaxation responses to bradykinin and superoxide dismutase of the uterine and renal arteries and to determine the role of nitric oxide in that response.


METHODS
Ten nulliparous, ovariectomized nonpregnant sheep received either estradiol-17beta or vehicle solution. In vitro studies evaluating vasorelaxation were done with either bradykinin or superoxide dismutase. The nitric oxide inhibitor nomega-nitro-L-arginine methyl ester was used to determine the role of nitric oxide in this process. Nitric oxide synthase activity was assessed by measuring citrulline generation.


RESULTS
We found a dose dependency of relaxation to bradykinin and superoxide dismutase. Estrogen enhanced this response in uterine arteries. Estrogen increased citrulline generation in uterine but not renal arteries. Nomega-nitro-L-arginine methyl ester blocked relaxation responses and citrulline generation in both arteries.


CONCLUSIONS
In nonpregnant sheep we found that nitric oxide release and nitric oxide synthase activity is enhanced by estrogen in the uterine arteries but not in the renal arteries. Increases in nitric oxide synthase activity may be important in the hyperemic response of the uterus during estrus.
Veille
J C
JC
Department of Obstetrics and Gynecology, Bowman Gray School of Medicine, Winston-Salem, NC 27157, USA.
Li
P
P
Eisenach
J C
JC
Massmann
A G
AG
Figueroa
J P
JP
D000704:Analysis of Variance; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001158:Arteries / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D001920:Bradykinin / Q000494:pharmacology; D002956:Citrulline / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D012077:Renal Artery / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D012756:Sheep; D013482:Superoxide Dismutase / Q000494:pharmacology; D014599:Uterus / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects*
D004791:Enzyme Inhibitors; D002956:Citrulline; D009569:Nitric Oxide; D004958:Estradiol; D001120:Arginine; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase; D001920:Bradykinin; D019331:NG-Nitroarginine Methyl Ester