Nitric oxide synthases in the human cervix at term pregnancy and effects of nitric oxide on cervical smooth muscle contractility.
OBJECTIVE
The purpose of the study was to determine whether a nitric oxide-generating system exists in the uterine cervix at term pregnancy and to study the effects of nitric oxide on contracting cervical strips.


METHODS
Tissue specimens were obtained from the cervices of women after deliveries and at elective cesarean deliveries. Immunohistochemical techniques and immunoblotting were used to identify isoforms of nitric oxide synthase. The effects of nitric oxide on cervical contractility were examined by the addition of nitroglycerin or spermine NONOate [(Z)-1-(N -[3-aminopropyl]-N -[4-(3-aminopropyl-ammonio)butyl]-amino)-diazen-1-ium-1,2-++ +diolate] to organ baths.


RESULTS
Immunohistochemical examination demonstrated positive staining for both endothelial and inducible nitric oxide synthase. Both isoforms of nitric oxide synthase were clearly detectable by immunoblotting. Significant inhibition of contractile activity (10(-7)-10(-5) mol/L) was observed when nitroglycerin or spermine NONOate was administered.


CONCLUSIONS
An endogenous nitric oxide system is present in the uterine cervix at term, and this tissue is responsive to nitric oxide, which causes relaxation of the cervical muscle.
Ekerhovd
E
E
Department of Obstetrics and Gynecology, Göteborg University, Göteborg, Sweden.
Brännström
M
M
Weijdegârd
B
B
Norström
A
A
D000328:Adult; D002584:Cervix Uteri / Q000201:enzymology / Q000502:physiology*; D004848:Epithelium / Q000201:enzymology; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007743:Labor, Obstetric; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000032:analysis*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D011247:Pregnancy
D020030:Nitric Oxide Donors; D009569:Nitric Oxide; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III