Nitric oxide mediated inhibition of contractile activity in the human uterine cervix.
Nitric oxide (NO) is an important modulator of contractile activity in various tissues. The aim of the present study was to investigate the possible existence of an NO system within the human uterine cervix and to study the effects of NO on the cervix in early pregnancy. Cervical tissue specimens were obtained from 24 women in connection with first trimester legal abortion. NADPH diaphorase staining was used to identify nitric oxide synthase activity within the cervical tissue. Cylindrical tissue specimens were mounted in organ bath chambers for isometric registration of contractile activity. The presence of a functional NO system in the cervix was investigated by adding either sodium nitroprusside or spermine NONOate, two different NO donors, or 8-bromo cGMP, an analogue of the second messenger cyclic guanosine monophosphate (cGMP), to the organ baths. Positive NADPH diaphorase staining was clearly observed in the walls of blood vessels, in cervical smooth muscle cells, and cells scattered in the connective tissue. The NO donating drugs sodium nitroprusside and spermine NONOate both caused a dose-dependent inhibition of spontaneous contractile activity with significant inhibition at concentrations of 10(-5) and 10(-7) M respectively. Furthermore, the participation of NO in the regulation of cervical contractility was indicated by a significant concentration-dependent inhibition of spontaneous contractions when 8-bromo cGMP (10(-5)-10(-3) M) was added to the organ baths. The study indicates the existence of an NO system within the human uterine cervix and a role of NO in control of cervical function.
Ekerhovd
E
E
Department of Obstetrics and Gynaecology, Göteborg University, Sahlgrenska University Hospital, Sweden.
Brännström
M
M
Delbro
D
D
Norström
A
A
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000328:Adult; D020070:Cervical Ripening / Q000502:physiology; D002584:Cervix Uteri / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides; D009599:Nitroprusside / Q000494:pharmacology; D011247:Pregnancy; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology
D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; C091861:spermine nitric oxide complex; D009599:Nitroprusside; D015124:8-Bromo Cyclic Adenosine Monophosphate; D013096:Spermine; D009569:Nitric Oxide; D009252:NADPH Dehydrogenase