Nguyen V H, Markwardt F
Julius-Bernstein-Institut for Physiology, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany.
Exp Dermatol. 2002 Aug;11(4):319-26. doi: 10.1034/j.1600-0625.2002.110405.x.
Patch-clamp recordings were carried out in the inside-out configuration in human keratinocytes of the cell line HaCaT. Patch pipettes were filled with 150 mM KCl, 1 mM CaCl(2) and 10 mM HEPES. In symmetrical KCl solutions, single channel currents from a large conductance channel (about 170 pS) were measured. Replacement of 120 mM KCl by K-aspartate had only a minor influence on the single channel conductance and on the reversal potential. In intracellular solution in which K(+) has been replaced by Na(+) or NMDG(+), the reversal potential shifted to > + 40 mV indicating K(+) as the main charge carrier. The channels were neither dependent on intracellular Ca(2+) (between 0.8 nM and 10 micro M), ATP (at 0 and 1 mM) nor Mg(2+) (at 0 and 0.5 mM). The mean current showed an outward rectification that can be mainly attributed to the voltage dependence of the open probability. The channels displayed bursting kinetics with a mean open time of about 2 ms and closed times of about 0.2, 2 and 20 ms. The mean open probability was usually low (0.05) but increased occasionally (0.6) mainly due to a lower probability of long closings. We conclude that these K(+) channels contribute to the resting potential of human keratinocytes which may control the Ca(2+) influx and thereby their proliferation and differentiation.
采用内面向外式膜片钳技术，对人永生化角质形成细胞系HaCaT进行记录。膜片钳微电极内充150 mM KCl、1 mM CaCl₂和10 mM HEPES。在对称KCl溶液中，测量了一个大电导通道（约170 pS）的单通道电流。用天冬氨酸钾替代120 mM KCl对单通道电导和反转电位只有轻微影响。在K⁺被Na⁺或NMDG⁺替代的细胞内溶液中，反转电位移至> +40 mV，表明K⁺是主要的电荷载体。这些通道既不依赖细胞内Ca²⁺（0.8 nM至10 μM之间）、ATP（0和1 mM），也不依赖Mg²⁺（0和0.5 mM）。平均电流表现出外向整流，这主要可归因于开放概率的电压依赖性。这些通道呈现爆发式动力学，平均开放时间约为2 ms，关闭时间约为0.2、2和20 ms。平均开放概率通常较低（0.05），但偶尔会增加（0.6），主要是由于长时间关闭的概率较低。我们得出结论，这些K⁺通道有助于人角质形成细胞的静息电位，这可能控制Ca²⁺内流，从而影响其增殖和分化。
