ラット無毛部皮膚より単離したメルケル細胞の大コンダクタンスCa²⁺依存性K⁺電流

概要

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This study investigated the Ca2+-activated K+ currents (KCa) of Merkel cells, which were freshly dissociated from rat glabrous skin, using whole-cell and excised patch configurations of the patch clamp technique. With the whole-cell voltage clamp, the application of slow (50 mV/s) voltage ramps from -100 to +100 mV produced an N-shaped current-voltage (I-V) relationship. Maximum current activation occurred at +38.0 ± 10.6 mV (N = 14). Replacement of extracellular Ca2+ by Mg2+ and the addition of 2 mM EGTA abolished the N-shaped I-V relationship, and 1 mM TEA reduced it to < 40%. Using inside-out patches with symmetrical 150 mM KCl solutions, channels were observed with a slope conductance of 280 pS and a reversal potential of 0 mV. Reducing the [K+]o to 5 mM shifted the reversal potential, which was expected for a K+ selective channel. The channel open-state probability (Po) was increased by increasing cytosolic [Ca2+]i. Po also increased with depolarization. These data indicate the presence of large-conductance Ca2+-activated K+ (BKCa) channels in Merkel cells.
2013-03-00