Regulation of myometrial contraction by ATP-sensitive potassium (K_ATP) channel via activation of SUR2B and Kir 6.2 in mouse

Abstract

ATP-sensitive potassium (K_ATP) channels are well characterized in cardiac, pancreatic and many other muscle cells. In the present study, functional expression of the K_ATP channel was examined in non-pregnant murine longitudinal myometrium. Isometric contraction measurements and Western blot were used. K_ATP channel openers (KCOs), such as pinacidil, cromakalim, diazoxide and nicorandil, inhibited spontaneous myometrial contractions in a reversible and glibenclamide-sensitive manner. KCOs inhibited oxytocin (OXT)- and prostaglandin F_2α (PGF_2α)-induced phasic contractions in a glibenclamide-sensitive manner. SUR2B and Kir6.2 were detected by Western blot, whereas SUR1, SUR2A and Kir6.1 were not. These results show that pinacidl, cromakalim, diazoxide and nicorandil-sensitive K_ATP channels exist in murine myometrium, which are composed of SUR2B and Kir6.2. Based on the modulatory effects of the K_ATP channel on spontaneous contraction, OXT- and PGF_2α-induced contractions, K_ATP channels seem to play an essential role in murine myometrial motility via activation of SUR2B and Kir6.2.