Calcium-activated K+ channels as modulators of human myometrial contractile activity.

摘要: The role of Ca(2+)-activated potassium (KCa) channels in the regulation membrane potential, intracellular free calcium ([Ca2+]i) and contraction was investigated uterine smooth muscle myometrial cells. In an immortalized human cell line, oxytocin increased [Ca2+]i [3H]inositol phosphate formation. Relaxin attenuated oxytocin-induced increase [Ca2+]i. cell-attached patches, depolarization activated a large-conductance KCa channel (179 +/- 4 pS). Iberiotoxin (IbTX), potent blocker "maxi" (A. Galvez, G. Gimenez-Gallego, J. P. Reuben, L. Roy-Contanciin, Feigenbaum, Kaczorowski, M. Garcia. Biol. Chem. 265: 11083-11090, 1990) produced long closed events (approximately 6 min) these channels. agreement with this blockage, IbTX depolarized cells by 9.8 2.8 mV caused dose-dependent half-maximal effective concentration 0.79 nM. also phasic contractions strips both frequency force spontaneous estrogen-primed rat strips. Moreover, contractility affected 1 mM tetraethylammonium, that blocks when applied to extracellular side (G. Perez, Toro, S. D. Erulkar, E. Stefani. Am. Obstet. Gynecol. 168: 652-660, 1993). These results strongly suggest large conductance may actively participate control potential [Ca2+].