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一般认为在神经肌肉标本上,高频间接强直刺激诱发的串终板电位(train of endplate potentials,EPPs)的衰减是一种突触前现象。药物对衰减率R(第20个以后的平均EPP幅度与第1个EPP幅度的比值)的影响可作为判定药物对突触前作用的指标。但尚无直接实验证据排除突触后因素的参与。我们在不均匀牵张的膈肌标本(isolated nonuniform stretched muscle preparation,INSMP)上,排除任何药物和异常离子的影响,膜电位水平为-60±2mV,温度控制在31±1℃,接近正常生理状态情况下,用玻璃微电极在同一个运动终板上记录了串EPPs及微终板电位(MEPP),同时还记录了只反映突触后膜兴奋性大小的外源性乙酰胆碱诱发的乙酰胆碱
It is generally believed that attenuation of train of endplate potentials (EPPs) induced by high-frequency indirect tonic stimulation is a presynaptic phenomenon in neuromuscular specimens. The influence of the drug on the decay rate R (the ratio of the mean EPP amplitude after the 20th and the 1st EPP amplitude) can be used as an index to determine the presynaptic effect of the drug. However, there is no direct experimental evidence to exclude the involvement of postsynaptic factors. We excluded any drug and abnormal ions on isolated nonuniform stretched muscle preparations (INSMP) with a membrane potential level of -60 ± 2 mV and temperature control of 31 ± 1 ° C, approaching the normal physiological state In this case, string EPPs and microendothelial potential (MEPP) were recorded on the same motor endplate with glass microelectrodes and acetylcholine induced by exogenous acetylcholine, which only reflects the size of postsynaptic membrane excitability