The effect of cocaine on membrane potential, on membrane depolarization by veratridine or elevated [K]o and on sodium/potassium permeability ratios in synaptosomes from the limbic cortex of the rat.
The effect of cocaine on membrane potential, on membrane depolarization by veratridine or elevated [K]o and on sodium/potassium permeability ratios in synaptosomes from the limbic cortex of the rat.
复制标题
可卡因对膜电位、藜芦碱或升高的 [K]o 引起的膜去极化以及对大鼠边缘皮质突触体中钠/钾通透性比率的影响。
DOI：
10.1016/0028-3908(93)90100-h
复制
发表时间：
1993
影响因子：
4.7
通讯作者：
Ondo,JG
中科院分区：
文献类型：
--
作者：
Wheeler,DD;Edwards,AM;Ondo,JG
Effects of cocaine on the synaptosomal membrane potential (Em), on membrane depolarization induced by veratridine or elevated [K]oand on sodium/potassium permeability ratios (pNa/pK), have been measured in buffer containing either low or high [Na]. Fluorescence of the dye rhodamine 6G was used to measure the membrane potential. Cocaine began to reduce theEm(depolarized) at concentrations between 10−6and 10−5M in low [Na] buffer and between 10−5and 10−4M in high [Na] buffer. Maximum depolarization (with 10−3M cocaine) was 21 mV in low [Na] buffer and 11 mV in high [Na] buffer.Cocaine also reduced the depolarization caused by veratridine or elevated [K]o; the effective concentration of cocaine in reducing the response to veratridine was one-tenth that necessary to reduce the response to elevated [K]o. The antagonism by cocaine of the response to veratridine was similar to that found by other investigators; however, this action would tend to oppose depolarization and thus cannot explain the depolarizing effect of cocaine alone. The antagonism by cocaine of the depolarization caused by elevated [K] was consistent with a reduction in pK; such a change in pK could explain the observed reduction inEmcaused by cocaine alone.The effect of cocaine (10−3M) on theEmwas also measured as a function of [K]oat low and high [Na]o. Cocaine caused membrane depolarization at all [K]o's (3.9−19.2 mV), an effect that was somewhat greater in the low [Na] medium. These measurements ofEmwere fitted to the Goldman equation and the ratio of pNa/pK estimated. The presence of cocaine increased the estimate of pNa/pK by 45.7%, presumably by reducing pK.
