Contribution of nonendothelial nitric oxide to altered rat uterine resistance artery serotonin reactivity during pregnancy.
OBJECTIVE
The aims of this study were to evaluate the effects of pregnancy on the serotonin reactivity of the mesometrial arteries and to assess the relative contribution of endothelial and smooth muscle cells to the overall effect.


METHODS
Arteries were obtained from nonpregnant (n = 20) and late pregnant (n = 28) Sprague-Dawley rats and were cannulated in the chamber of an arteriograph. Changes in lumen diameter were measured by a video dimension analyzer. Statistical analysis used 2-way analysis of variance, followed by Bonferroni test.


RESULTS
Intact vessels from late pregnant versus nonpregnant animals were significantly less sensitive to the constrictor effects of serotonin at concentrations <100 nmol/L. A role for endothelial nitric oxide was indicated on the basis of the effects of denudation and N(omega)-nitro-L-arginine. Furthermore, the additional effect of N(omega)-nitro-L-arginine in denuded vessels from pregnant animals suggests that another, nonendothelial source of nitric oxide also contributes to the effect.


CONCLUSIONS
Pregnancy significantly decreases uterine resistance artery sensitivity to serotonin. This difference in sensitivity is due to the enhanced production of nitric oxide by endothelial cells and, most likely, by vascular smooth muscle.
Department of Obstetrics and Gynecology, University of Vermont College of Medicine. Burlington, 05405, USA.
Maurizio
M
Mandalà
Natalia
N
Gokina
George
G
Osol
D000792:Angiography; D000818:Animals; D001158:Arteries / Q000378:metabolism / Q000502:physiology; D004730:Endothelium, Vascular / Q000378:metabolism / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000502:physiology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D019335:Nitroarginine / Q000494:pharmacology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D014599:Uterus / Q000098:blood supply*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D019335:Nitroarginine; D009569:Nitric Oxide; D012701:Serotonin