Effects of L-type Ca2+-channel blockade, K+ATP-channel opening and nitric oxide on human uterine contractility in relation to gestational age and labour

M. Longo, V. Jain, Y. P. Vedernikov, G. D.V. Hankins, R. E. Garfield, G. R. Saade

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Relative uterine inactivity during pregnancy changes to vigorous rhythmic contractility during labour. We hypothesized that mechanisms involved in the regulation of uterine quiescence and contractility differ between term and preterm myometrium and in labour and non-labour states. Myometrial strips, prepared from biopsies taken at Caesarean section from labouring and non-labouring women preterm and at term, were mounted in organ chambers for isometric tension recording. Oxytocin (10-9 mol/l) was added to maintain stable contractions, and effects of various inhibitors of uterine contractility were studied. The inhibitory effects of L-type Ca2+-channel blocker nifedipine and ATP-sensitive K+-channel opener pinacidil were greater in myometrium from the non-labour versus the labour group, both preterm and at term. In addition, pinacidil's effect was greater at term compared with preterm in the non-labour group. Mg2+ and the nitric oxide donor sodium nitroprusside significantly inhibited contractility in all groups without significant differences with regard to labour or gestational age. Decreased inhibition of human uterine contractility by L-type Ca2+-channel blockers and K+ATP-channel openers in preterm and term labour may reflect changes in expression and activity of these channels. Effects of nitric oxide and Mg2+ are not affected by gestational age or labour.

Original languageEnglish (US)
Pages (from-to)159-164
Number of pages6
JournalMolecular Human Reproduction
Issue number3
StatePublished - Mar 1 2003


  • Channels
  • Human
  • Labour
  • Pregnancy
  • Uterus

ASJC Scopus subject areas

  • Reproductive Medicine
  • Embryology
  • Molecular Biology
  • Genetics
  • Obstetrics and Gynecology
  • Developmental Biology
  • Cell Biology


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