Potassium channel openers' effects on pregnant uterine muscle before and after labor: possible use to delay childbirth

Levcromakalim and pinacidil are potent inhibitors of contractions in isolated pregnant human myometrium.

• Both potassium channel openers effectively reduced spontaneous and induced contractions in myometrial samples from 67 women.
• The inhibition of contractions occurred with low concentrations of extracellular potassium chloride but not with high concentrations.
• Glibenclamide acted as a competitive antagonist to the inhibitory effects of levcromakalim and pinacidil.
• No antagonistic effect was observed with tolbutamide.
• These findings indicate that activating potassium channels may contribute to muscle relaxation in the pregnant uterus.

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