Objective: This study aimed to investigate the endothelium-dependent relaxation of uterine small arteries from pregnant nonsmokers, smokers, and ex-smokers who stopped smoking early in pregnancy.
Study design: Uterine arteries were dissected from myometrial biopsies obtained during elective cesarean sections of 34 uncomplicated, singleton pregnancies, and the vascular function was assessed in a wire myograph for isometric recordings. Serum cotinine verified self-reported smoking; 15 were nonsmokers, 10 were smokers, and 9 were ex-smokers.
Results: Arteries from smokers and ex-smokers had reduced bradykinin-induced relaxation compared to arteries from nonsmokers (P < .05). The relaxation response to the nitric oxide donor sodium nitroprusside was similar in arteries from nonsmokers and smokers but was better in arteries from ex-smokers (P < .05).
Conclusion: The findings suggest that maternal smoking reduces endothelium-dependent nitric oxide-mediated relaxation in uterine small arteries and that smoking cessation early in pregnancy does not fully abolish this deleterious effect, despite improvement in relaxation to nitroprusside.
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