Aiuchi T, Daimatsu T, Nakaya K, Nakamura Y
Biochim Biophys Acta. 1982 Mar 8;685(3):289-96. doi: 10.1016/0005-2736(82)90070-0.
The intensity of rhodamine 6G fluorescence was found to be a useful scale for measuring the membrane potential in synaptosomes. The fluorescence of rhodamine 6G in synaptosomal suspensions increases with depolarization in the synaptosomes induced by the replacement of cations in the medium or by the addition of agents known to depolarize the membrane potential. Considering the character of the dye, we have derived an equation which gives the relation between the fluorescence intensity of the dye and the membrane potential. The change in membrane potential (diffusion potential) of synaptosomes was calculated using the equation. The calculated membrane potential was proportional to the logarithm of the K+ concentration above 20 mM, and the slope of membrane potential against log [K+] was about 52 mV per decade of concentration. The permeability ratio (Px/Pk; the ratio of the permeability constants of a given cation, X+, and K+) was estimated from the calculated membrane potential.
若丹明6G荧光强度被证明是测量突触体膜电位的一个有用指标。在突触体悬浮液中，若丹明6G的荧光会随着培养基中阳离子的置换或添加已知可使膜电位去极化的试剂所诱导的突触体去极化而增强。考虑到该染料的特性，我们推导出了一个方程，该方程给出了染料荧光强度与膜电位之间的关系。利用该方程计算突触体膜电位的变化（扩散电位）。计算得到的膜电位与20 mM以上K⁺浓度的对数成正比，膜电位相对于log [K⁺]的斜率约为每十倍浓度变化52 mV。通过计算得到的膜电位估算通透率（Px/Pk；给定阳离子X⁺与K⁺的通透常数之比）。
