Coronado R
Department of Physiology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030.
Circ Res. 1987 Oct;61(4 Pt 2):I46-52.
Sodium current in the absence of divalents was measured through single calcium channels of skeletal muscle transverse tubules incorporated into planar bilayers composed of the negatively charged lipid phosphatidylserine (PS) and neutral lipid phosphatidylethanolamine (PE). Channel kinetics in PE and PS are characterized by the simultaneous presence of openings of long duration (greater than 200 msec) and openings of brief duration (less than 20 msec) grouped into bursts. Accordingly, exponential distributions of open-channel lifetimes could be fitted with at least two time constants. An increase in bilayer mole fraction of PS, from XPS = 0 (pure PE) to XPS = 1.0 (pure PS), decreased open-channel lifetimes by approximately twofold to threefold. Calculations using the Gouy-Chapman theory indicate that channel lifetimes do not correlate with bilayer surface potentials generated by PS.
在不含二价离子的情况下，通过整合到由带负电荷的脂质磷脂酰丝氨酸（PS）和中性脂质磷脂酰乙醇胺（PE）组成的平面双层中的骨骼肌横管的单个钙通道来测量钠电流。PE和PS中的通道动力学特征是同时存在持续时间长（大于200毫秒）的开放和分组为爆发的持续时间短（小于20毫秒）的开放。因此，开放通道寿命的指数分布可以用至少两个时间常数来拟合。PS的双层摩尔分数从XPS = 0（纯PE）增加到XPS = 1.0（纯PS），使开放通道寿命缩短了约两倍至三倍。使用古伊-查普曼理论进行的计算表明，通道寿命与PS产生的双层表面电位无关。
