急性分离大鼠新皮层神经元K_(ATP)通道的多电导状态

Multiple conductance states of ATP-sensitive potassium channel in acutely dissociatedcerebral neurons of rats

在１９３例急性分离大鼠皮层神经元内面向外式记录膜片上，记录到２例能为ＡＴＰ和优降糖所阻断的含有亚电导的通道电流。其电流幅度分布直方图符合高斯分布，并能很好地进行二级拟合；主电导水平分别为１９１．８ｐＳ和１９４．５ｐＳ，亚电导水平分别为１５３．２ｐＳ和１１６.１ｐＳ；亚电导成份分别占单位事件总数的３５．０５％和２９.８４％；通道活动呈高电流水平与低电流水平交替开放状态，没有高低电流叠合现象。这些结果表明这种Ｋ_ＡＴＰ通道的多电导开放电流不是两个或多个独立通道的开放所致，而是同一通道的不同亚型状态交互活动（即高电导和低电导状态相互转换）的表现。从而提示神经细胞膜上的Ｋ_ＡＴＰ通道可能受某种或某些膜内外环境的变化影响导致其构象改变，从而引发多种亚型交替活动现象。

Two subconductance states in ATP-sensitive potassium channels were recorded in 193 inside-out patches in acutelydissociated cerebral neurons of rats. The single-channel currents with one subconductance were completely suppressed ATP andglibenclamide and the distribution of its two current amplitudes were fitted with the sum of two Gaussian components. The mainconductances were 191.8 pS and 194.5 pS respectively, and the subconductances were 153.2 pS and 116.1 pS, and there were35.05% and 29.84% events in each two epsodes. The currents with main conductance interlaced with those with subconductance, andone did not overlap with the another. It was indicated that the multiple conductance channel currents were not due to two or moresingle channel openings, but due to interlacing activity different subconductance states of a single channel. It is suggested that somefactors inside or outside membrane could induce the conformational change of neuronal membrance, leading to interlacing activity ofa single K_ATP, channel with two conductance states.