Participation of BKCa2+ and KATP potassium ion channels in the contractility of human term pregnant myometrium in in vitro conditions

Aim: The aim of this study was to assess the participation of ligand-sensitive potassium large conductance calcium-activated ion channels (BKCa2+) and adenosine triphosphate (ATP)-sensitive potassium ion channels (K-ATP) using its openers (NS1619 and pinacidil) in the contractility of human term pregnant myometrium in in vitro conditions. Methods: Human myometrium tissue samples were collected from term pregnant laboring women who had to undergo cesarean section. The contractility of myometrium was induced by the application of oxytocin into the organ bath. Myometrial strips were incubated with the opener of BKCa2+ potassium ion channels NS1619 and its antagonist tetraethylammonium or with the opener of K-ATP potassium ion channels pinacidil and its antagonist glibenclamide. Results: K-ATP potassium ion channel's opener pinacidil significantly decreased amplitude of myometrial contractions (P < 0.05) as well as frequency of myometrial contractions (P < 0.05) provoked by oxytocin in human term pregnant myometrium in in vitro conditions. The inhibition of the human myometrial contractions of pinacidil was significantly antagonized by its specific antagonist glibenclamide (P < 0.05). BKCa2+ potassium ion channel's opener NS1619 did not significantly affect the contractile activity of human term pregnant myometrium induced by the application of oxytocin in in vitro conditions. Conclusion: In our experimental study we found that the participation of BKCa2+ and K-ATP potassium ion channels in the contractility of human term pregnant myometrium in labor is probably different.