Vautrin J, Kriebel M E
Université Paris XII, Créteil, France.
J Neurosci Res. 1992 Mar;31(3):502-6. doi: 10.1002/jnr.490310313.
Miniature endplate potentials (MEPPs) with slow rising phase can be attributed either to burst of transmitter releases or to distortion of conduction from remote releasing sites. The spontaneous activity of neuromuscular junctions recorded extracellularly at mouse diaphragms using sharp electrodes was analyzed to test these two hypotheses. The miniature junctional potentials (MEJPs) frequencies observed intracellularly as compared to MEPP frequency measured intracellularly in controls indicate that most events recorded extracellularly are induced by the presence of the electrode. All types of MEPPs (bell-MEPPs, skew-MEPPs, slow-, and giant MEPPs) previously described with intracellular recording methods (Vautrin and Kriebel, Neuroscience 41:71-88, 1991) were observed extracellularly and showed similar characteristics. This means that the presynaptic and postsynaptic zones that generate these synaptic events are restricted within areas of a few micrometers squared of synaptic contact. Long rise times of extracellularly recorded synaptic spontaneous events may be explained by multiple transmitter releases at intervals shorter than the rise time of individual events, which postsynaptic responses fuse into a single peak.
上升相缓慢的微小终板电位（MEPPs）可能归因于递质释放的阵发性，或者是来自远处释放位点的传导失真。使用尖锐电极在小鼠膈肌上细胞外记录神经肌肉接头的自发活动，以检验这两种假设。与在对照中细胞内测量的MEPP频率相比，细胞内观察到的微小接头电位（MEJPs）频率表明，细胞外记录的大多数事件是由电极的存在所诱发的。以前用细胞内记录方法描述的所有类型的MEPPs（钟形MEPPs、倾斜MEPPs、缓慢和巨大MEPPs）（Vautrin和Kriebel，《神经科学》41:71 - 88，1991）在细胞外均被观察到，且表现出相似的特征。这意味着产生这些突触事件的突触前和突触后区域被限制在几平方微米的突触接触区域内。细胞外记录的突触自发事件的长上升时间可能是由于递质的多次释放，其间隔时间短于单个事件的上升时间，从而使突触后反应融合成一个单峰。
