title: Orai1 protein expression and the role of calcium release-activated calcium channels in the contraction of human term-pregnant and non-pregnant myometrium.
abstract: OBJECTIVE
  This experimental in vitro study examined differences in the expression and activity of calcium release-activated calcium (CRAC) channels of human term-pregnant and non-pregnant myometrium.
  
  
  METHODS
  The tissue samples were obtained from term-pregnant myometrium in labor of women undergoing cesarean section and from non-pregnant myometrium of women undergoing total hysterectomy due to uterine myoma. The expression of Orai1 protein, a pore-forming subunit of CRAC channels, in human myometrium was examined using immunohistochemistry. CRAC channel involvement in the amplitude and frequency of myometrial contractions was evaluated in vitro using a tissue bath method with a CRAC ion channel blocker 3-fluropyridine-4-carboxylic acid (FPCA).
  
  
  RESULTS
  Decreased Orai1 expression was observed in human term-pregnant laboring myometrium compared with non-pregnant myometrium. However, the initial oxytocin-induced contraction of myometrium was significantly suppressed at different doses of FPCA in both non-pregnant human isolated myometrium and non-pregnant myometrium. The frequency of contractions was the most significantly reduced at the lowest dose of FPCA in non-pregnant myometrium and remained suppressed at all doses of FPCA in term-pregnant myometrium. Salbutamol was shown as more effective in suppression of amplitude in term-pregnant isolated myometrium.
  
  
  CONCLUSIONS
  Our results provide the first information about the changes in the Orai1 protein expression and activity of human myometrial CRAC channels in term-pregnant laboring myometrium.
authors.affiliation: Department of Pharmacology, Jessenius Faculty of Medicine Martin, Comenius University Bratislava, Martin, Slovak Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Sutovska
authors.forename: Michaela
authors.initials: M
authors.lastname: Kocmalova
authors.forename: Vladimira
authors.initials: V
authors.lastname: Sadlonova
authors.forename: Karol
authors.initials: K
authors.lastname: Dokus
authors.forename: Marian
authors.initials: M
authors.lastname: Adamkov
authors.forename: Jan
authors.initials: J
authors.lastname: Luptak
authors.forename: Sona
authors.initials: S
authors.lastname: Franova
mesh_terms: D000420:Albuterol / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D005260:Female; D006801:Humans; D007539:Isonicotinic Acids / Q000494:pharmacology; D009215:Myometrium / Q000187:drug effects / Q000378:metabolism*; D000071740:ORAI1 Protein / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D014590:Uterine Contraction / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
chemical_list: C576491:3-fluoropyridine-4-carboxylic acid; D002121:Calcium Channel Blockers; D007539:Isonicotinic Acids; D000071740:ORAI1 Protein; D000420:Albuterol
keywords: Orai1 protein; contractions; labor; myometrium; oxytocin