大鼠纹状体边缘区神经元中乙酰胆碱激活的离子通道特性

Acetylcholine-activated ion channels in neurons of the marginal division acutely dissociated from rat striatum

用细胞贴附式膜片钳技术研究了急性分离的新生SD大鼠纹状体边缘区神经元中乙酰胆碱激活的离子通道的特性。发现通道有25PS和60PS两种电导状态，25PS通道为主要类型，因此，本文主要报道25PS通道的特性。ACh激活的单通道电流为快速内向电流，随着超极化程度增加而增加，反转电位约为0mV。通道开放具单个开放和簇状开放，其开放时间均可权指数拟和，单个开放时间常数为0．29ms和1.84ms，簇状开放时间常数为1．96ms和18.24ms。平均关闭时间也可双指数拟和，两个时间常数为1．70ms和54．00ms。通道开放概率为0．012，未表现出电压依赖性。提示纹状体边缘区神经元上存在乙酸胆碱受体离子通道。根据特性证实为烟碱型离子通道。

Cell-attached mode of patch clamp technique was employed to investigate the properties of acetylcholine-induced ionchannels in acutely dissociated neurons from the marginal division (MrD) of the rat striamm. Two kinds of conductance states (25 pSand 60 pS) were detected, and the ion channel with conductance of 25 pS is the main type and the properties of it are reported here.The amplitudes of inward currents increased with hyperpolorization and the reversal potential was O mV; both isolated short-durationopening and burst openings were recorded in neurons of the MrD. Two time constants were 0.29 ms, 1 .84 ms and 1 .96 ms, 18.24 ms,respectively: Averape close time can be fitted with two exponential functions, the two time constants were 1.70 ms apd 54.0 ms.Probability of channel opening was about 0.012 and no voltage-dependence was found. It is suggested that there are nicotinicacetylcholine receptor ion channels existing in the neurons of the MrD.