Neumcke B, Stämpfli R
Biochim Biophys Acta. 1983 Jan 5;727(1):177-84. doi: 10.1016/0005-2736(83)90382-6.
(1) Na+ currents and Na+-current fluctuations were measured in myelinated frog nerve fibres at 15 degrees C during 7.7 ms depolarizations to V = 40, 60 and 80 mV. (2) The conductance gamma of a single Na+ channel and the number No of channels per node were calculated from ensemble average values of the mean Na+ current and the variance of Na+-current fluctuations. (3) For a hyperpolarizing holding potential of VH = -28 mV the mean values of the channel conductance and number were gamma = 9.8 pS and No = 74000. (4) After changing the holding potential to the resting potential (VH = 0) the conductance gamma increased by a factor of 1.37 whereas the number No decreased by a factor of 0.60. (5) Addition of 8 nM tetrodotoxin at a holding potential of VH = -28 mV increased gamma by a factor of 1.55 and reduced No by a factor of 0.25. (6) The increase of the channel conductance at reduced channel numbers suggests negative cooperativity between Na+ channels in the nodal membrane.
(1) 在15摄氏度下，对有髓青蛙神经纤维进行7.7毫秒的去极化至V = 40、60和80毫伏，测量其钠离子电流和钠离子电流波动。(2) 根据平均钠离子电流的总体平均值和钠离子电流波动的方差，计算单个钠离子通道的电导γ和每个节点的通道数量No。(3) 对于-28毫伏的超极化钳制电位，通道电导和数量的平均值分别为γ = 9.8皮安和No = 74000。(4) 将钳制电位改为静息电位（VH = 0）后，电导γ增加了1.37倍，而数量No减少了0.60倍。(5) 在VH = -28毫伏的钳制电位下添加8纳摩尔的河豚毒素，使γ增加了1.55倍，No减少了0.25倍。(6) 在通道数量减少时通道电导增加，这表明节点膜中钠离子通道之间存在负协同作用。
