Lepple-Wienhues A, Berweck S, Böhmig M, Leo C P, Meyling B, Garbe C, Wiederholt M
Institut für Klinische Physiologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Hindenburgdamm 30, 12200 Berlin, Germany.
J Membr Biol. 1996 May;151(2):149-57. doi: 10.1007/s002329900066.
K+ channels, membrane voltage, and intracellular free Ca2+ are involved in regulating proliferation in a human melanoma cell line (SK MEL 28). Using patch-clamp techniques, we found an inwardly rectifying K+ channel and a calcium-activated K+ channel. The inwardly rectifying K+ channel was calcium independent, insensitive to charybdotoxin, and carried the major part of the whole-cell current. The K+ channel blockers quinidine, tetraethylammonium chloride and Ba2+ and elevated extracellular K+ caused a dose-dependent membrane depolarization. This depolarization was correlated to an inhibition of cell proliferation. Charybdotoxin affected neither membrane voltage nor proliferation. Basic fibroblast growth factor and fetal calf serum induced a transient peak in intracellular Ca2+ followed by a long-lasting Ca2+ influx. Depolarization by voltage clamp decreased and hyperpolarization increased intracellular Ca2+, illustrating a transmembrane flux of Ca2+ following its electrochemical gradient. We conclude that K+ channel blockers inhibit cell-cycle progression by membrane depolarization. This in turn reduces the driving force for the influx of Ca2+, a messenger in the mitogenic signal cascade of human melanoma cells.
钾离子通道、膜电压和细胞内游离钙离子参与调节一种人黑色素瘤细胞系（SK MEL 28）的增殖。运用膜片钳技术，我们发现了一种内向整流钾离子通道和一种钙激活钾离子通道。内向整流钾离子通道不依赖钙，对蝎毒素不敏感，且承载了全细胞电流的主要部分。钾离子通道阻滞剂奎尼丁、氯化四乙铵和钡离子以及细胞外钾离子浓度升高会引起剂量依赖性的膜去极化。这种去极化与细胞增殖的抑制相关。蝎毒素既不影响膜电压也不影响增殖。碱性成纤维细胞生长因子和胎牛血清会诱导细胞内钙离子出现一个短暂峰值，随后是持续的钙离子内流。通过电压钳进行的去极化会降低细胞内钙离子浓度，而超极化则会增加细胞内钙离子浓度，这表明钙离子会顺着其电化学梯度进行跨膜流动。我们得出结论，钾离子通道阻滞剂通过膜去极化抑制细胞周期进程。这进而降低了钙离子内流的驱动力，而钙离子是人类黑色素瘤细胞有丝分裂信号级联反应中的一种信使。
