Corda D, Pasternak C, Shinitzky M
J Membr Biol. 1982;65(3):235-42. doi: 10.1007/BF01869967.
Diffusion potential of potassium ions was found in unilamellar vesicles of phosphatidyl choline. The vesicles, which included potassium sulfate buffered with potassium phosphate were diluted into an analogous salt solution made of sodium sulfate and sodium phosphate. The diffusion potential was created by the addition of the potassium-ionophore, valinomycin. The change in lipid microviscosity, ensuing the formation of membrane potential, was measured by the conventional method of fluorescence depolarization with 1,6-diphenyl-1,3,5-hexatriene as a probe. Lipid microviscosity was found to increase with membrane potential in a nonlinear manner, irrespective of the potential direction. Two tentative interpretations are proposed for this observation. The first assumes that the membrane potential imposes an energy barrier on the lipid flow which can be treated in terms of Boltzmann-distribution. The other interpretation assumes a decrease in lipid-free volume due to the pressure induced by the electrical potential. Since increase in lipid viscosity can reduce lateral and rotational motions, as well as increase exposure of functional membrane proteins, physiological effects induced by transmembrane potential could be associated with such dynamic changes.
在磷脂酰胆碱单层囊泡中发现了钾离子的扩散电位。将含有用磷酸钾缓冲的硫酸钾的囊泡稀释到由硫酸钠和磷酸钠制成的类似盐溶液中。通过添加钾离子载体缬氨霉素产生扩散电位。用1,6 - 二苯基 - 1,3,5 - 己三烯作为探针，通过传统的荧光去极化方法测量膜电位形成后脂质微粘度的变化。发现脂质微粘度随膜电位以非线性方式增加，与电位方向无关。针对这一观察结果提出了两种初步解释。第一种假设膜电位对脂质流动施加了一个能量屏障，这可以根据玻尔兹曼分布来处理。另一种解释假设由于电势引起的压力导致脂质自由体积减小。由于脂质粘度的增加可以减少横向和旋转运动，以及增加功能性膜蛋白的暴露，跨膜电位诱导的生理效应可能与这种动态变化有关。
