Kriebel M E, Florey E
Neuroscience. 1983 Jul;9(3):535-47. doi: 10.1016/0306-4522(83)90172-0.
Miniature endplate potential (MEPP) amplitude distributions, MEPP frequencies and percentages of small MEPPs were determined as well as synaptic vesicle diameters and numbers in the frog neuromuscular junction during La3+ treatment. MEPP frequencies initially increased by two orders of magnitude and then fell to very low values. La3+ treatment had an initial postsynaptic effect making the MEPPs larger. Prolonged treatment had a variable effect on MEPP amplitudes. There were considerable variations in MEPP frequencies in adjacent junctions so single junctions on edge muscle fibers were recorded for the duration of many experiments and later identified in the electron microscope. Therefore, the physiological and morphological conditions of a given identified junction could be compared. There was a loss of synaptic vesicles and no change in mean diameter during depletion. During high MEPP frequencies infoldings occurred on the axolemma and these disappeared when MEPP frequencies decreased towards the end of the La3+ treatment. After 3-4 h of La3+ treatment, the overall frequency of MEPPs dropped and many were composed of a small class of MEPPs. It is suggested that the morphological correlate of small MEPPs, as well as the classical bell-MEPPs is likely to be synaptic vesicles.
在La3+处理蛙神经肌肉接头期间，测定了微小终板电位（MEPP）的幅度分布、MEPP频率和小MEPP的百分比，以及突触小泡的直径和数量。MEPP频率最初增加了两个数量级，然后降至非常低的值。La3+处理最初具有突触后效应，使MEPP变大。长时间处理对MEPP幅度有可变影响。相邻接头的MEPP频率存在相当大的差异，因此在许多实验过程中记录了边缘肌纤维上单个接头的情况，随后在电子显微镜下进行鉴定。因此，可以比较给定鉴定接头的生理和形态条件。在耗尽过程中，突触小泡数量减少，平均直径没有变化。在MEPP频率较高时，轴膜出现内褶，当La3+处理接近结束时MEPP频率下降时，这些内褶消失。La3+处理3-4小时后，MEPP的总体频率下降，许多由一小类MEPP组成。有人提出，小MEPP以及经典的钟形MEPP的形态学相关物可能是突触小泡。
