Grishchenko I I, Naumov A P, Zubov A N
Neuroscience. 1983 Jul;9(3):549-54. doi: 10.1016/0306-4522(83)90173-2.
Currents through normal and aconitine-modified sodium channels in perfused neuroblastoma cells were measured under voltage-clamp conditions. Aconitine is shown to induce changes in channel selectivity so that channels become more permeable to NH4+ than to Na+. Aconitine induces the shift of voltage dependence of channel activation toward more negative potentials by about 20 mV. Aconitine-modified channels inactivate practically completely with a time-course similar to that for normal channels. Aconitine is effective when applied to either side of the membrane. Steady-state characteristics of the gating machinery of aconitine-modified channels are discussed in terms of three-state model. According to the model, aconitine increases the probability of finding the channel in open state, which is reflected in negative shift of the voltage dependence of activation. The model predicts that the larger this shift, the higher is the level of steady-state sodium conductance. The comparison of respective properties of aconitine-modified channels in neuroblastoma cell and frog nerve confirms this prediction. Aconitine is assumed to reach its receptor through the lipophilic part of the membrane.
在电压钳制条件下，测量了灌流神经母细胞瘤细胞中通过正常和乌头碱修饰的钠通道的电流。结果表明，乌头碱可诱导通道选择性发生变化，使通道对NH4+的通透性比对Na+的通透性更高。乌头碱使通道激活的电压依赖性向更负的电位方向偏移约20 mV。乌头碱修饰的通道几乎完全失活，其时间进程与正常通道相似。将乌头碱应用于膜的任一侧均有效。根据三态模型讨论了乌头碱修饰通道门控机制的稳态特征。根据该模型，乌头碱增加了通道处于开放状态的概率，这反映在激活电压依赖性的负向偏移上。该模型预测，这种偏移越大，稳态钠电导水平越高。对神经母细胞瘤细胞和蛙神经中乌头碱修饰通道各自特性的比较证实了这一预测。假定乌头碱通过膜的亲脂部分到达其受体。
