海马神经元膜片与细胞分离前后nAChR通道特性的改变

CHANGES OF SINGLE nAChR CHANNELS BEHAVIOURS IN EXCISED PATCHES OF HIPPOCAMPAL NEURONS

目的和方法：在新生大鼠海马神经元上，用膜片钳技术研究了乙酰胆碱（ＡＣｈ）受体单通道特性、离子选择性及细胞内物质对通道活动的影响。结果：该通道对单价阳离子通透，对Ｎａ＋和Ｋ＋的通透性相近，但不通透Ｃｌ－。当膜片与细胞分离后，单个独立短开放通道的开放时间τ０１、τ０２和开放概率分别下降了６５．８％、５０．８％和６８．４％；对于长开放通道影响更为明显，开放时间τｂ１、τｂ２和开放概率分别下降了３２．３％、８５．９％和８４．６％。结论：胞内物质如第二信使。

Abstract Aim and Methods: The patch clamp technique was used to examine the characteristics of single acetylcholine receptor channels, ion permeability and influence of cytoplasmic composition on it in cultured hippocampal neurons of neonatal rat. Results:Most of the patches had unitary conductance state of 20 pS. Ion permeability of nAChR channels were calculated from the reversal potentials. The channel was selective for cations. It was virtually impermeable for CI -. K + permeability was similar to that of Na +. The mean open times of the τ 01 .τ 02 and open probability of channel in the cell attached mode were decreased about 32.3%, 85.9%and 84.6%following excision, respectively. Which reduced more severely after excision in the patches where the majority of channel openings appeared as bursts than in the patches where isolated short opening were predominent. The mean burst duration τ b1 τ b2 and open probability decreased about 32.3%, 85.9% and 84.6% after excision.Conclusion: The changes seen indicate that cytoplasmic composition are necessary to the function of membrane channels. acetylcholine receptor; hippocampal neuron; patch clamp