Single channel currents from excised patches of muscle membrane.
Single channel currents from excised patches of muscle membrane.
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来自切除的肌膜斑块的单通道电流。
DOI：
10.1073/pnas.77.11.6930
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发表时间：
1980
影响因子：
11.1
通讯作者：
Patlak,J
中科院分区：
文献类型：
--
作者：
Horn,R;Patlak,J
通过单个乙酰胆碱激活的通道的电流进行了测量的膜碎片，已从大鼠肌肉肌管与补丁移液管撕裂。通过使用Neher的“吉欧姆密封”技术将膜碎片密封到移液管中，该技术还允许通过贴片电极对膜进行电压钳。突然从细胞中拔出电极会使膜斑兴奋。用氟离子取代浴液中的氯离子可以防止或逆转电极尖端处的膜密封成封闭囊泡的趋势。在电极尖端的单膜层可以保持功能长达30分钟。切除的表观单通道电导的影响最小。单通道电流的电流-电压关系显示内部（即，细胞质表面）暴露于浴溶液。在对称钠溶液中，电流-电压曲线几乎呈线性，并在约0 mV处反转。在40至500 mM NaF的其他洗浴溶液中，观察到的零电流电位接近于由能斯特方程预测的零电流电位。我们提出的证据表明，内部钠与通道相互作用，导致外向电流的饱和和内向电流的阻塞。在+100 mV时，内部Na的表观解离常数为138 mM。
The currents through single acetylcholine-activated channels were measured on membrane fragments that had been torn from rat muscle myotubes with patch pipettes. The membrane fragments were sealed into the pipette by using the "gigohm-seal" technique of Neher, which also permitted voltage clamp of the membrane via the patch electrode. Membrane patches were excited by sudden withdrawal of the electrode from the cell. Substitution of fluoride for chloride ions in the bathing solution could prevent or reverse the tendency for the membrane at the electrode tip to seal over into a closed vesicle. The single membrane layer at the electrode tip could remain functional for up to 30 min. The apparent single channel conductance was minimally affected by excision. The current-voltage relationships for the single channel currents show that the inside (i.e., cytoplasmic surface) of the membrane fragment was exposed to the bathing solution. In symmetric Na solutions the current-voltage curve was nearly linear and reversed at approximately 0 mV. In other bathing solutions from 40 to 500 mM NaF, the observed zero current potential was close to that predicted by the Nernst equation. We present evidence that internal Na interacts with the channel, causing both saturation of outward current and block of inward current. At + 100 mV the apparent dissociation constant for internal Na was 138 mM.