海马神经元乙酰胆碱激活通道在不同培养期的功能特性

CHANGES IN THE FUNCTIONAL CHARACTERISTICS OF ACETYLCHOLINE ACTIVATED CHANNELS OF HIPPOCAMPAL NEURONS AT DIFFERENT PERIODS OF CULTURE

用膜片箝技术对不同培养期的新生大鼠海马神经元上乙酰胆碱（ＡＣｈ）受体单通道特性进行了研究，结果表明不同培养期ＡＣｈ激活通道的电学特性不同。培养早期（１－２ｄ），２０ｐＳ通道占优势，开放以单个短开放事件为主，平均开放时间小于２ｍｓ。培养后期（１８—２ｌｄ），３ｌｐＳ通道为主，开放随膜片的不同可分成两类：即单个短开放（时间常数为０．３５ｍｓ和１．２９ｍｓ）和簇状开放（Ｂｕｒｓｔ）（时间常数为１．１５ｍｓ和９．６ｍｓ），同时也存在着以长Ｂｕｒｓｔ形式开放的２０ｐＳ通道。

Patch-clamp technique was used to examine activation of single acetylcholine receptor channels of hippocampal neurons of neonatal rat at different periods of culture.The conductance values showed substantial variation from patch to patch.Some of channels have the same conductance but are kinetically different.Changes in the electrophysiological behaviour of ACh-evoked channels were dependent on the duration of culture.In the earlier period(l-2 days),the 20-pS state was predominent.Isolated short openings were much more common with mean open times usually less than 2.0 ms.In the late period of culture(18-ZI days),the 31-pS state was predominant.The channel openings displays either as single events(T.l,0.35 ms;T.2,1.29 ms)or as bursts of events(T.l,1.15 ms;TbZ,9.6 ms)in different patches.However,20-pS state in the late period of culture could also be observed mostly as constituting events during the long burst.