骨骼肌兴奋收缩偶联时肌膜下小泡的超微结构变化

目的：从毫秒级功能变化水平实时观察骨骼肌肌膜下小泡在收缩潜伏期内的时相-形态变化。方法：采用双红外线探测器-计算机控制的电刺激-超低温快速冷冻固定同步技术，对电刺激后的蟾蜍骨骼肌组织作快速冷冻固定，冷冻置换，微波浸透包埋和超薄切片，在透射电镜下观察该骨骼肌细胞在电刺激后0．0ms，4．6ms，24ms的超微结构变化。结果：未加刺激的骨骼肌细胞的肌膜下仅见少量小泡分布；施加刺激4．6ms后肌膜下出现大量小泡，并由3～8个小泡融合成聚合体；24ms后小泡急剧减少，仅残留少量小泡紧靠肌膜下。结论：骨骼肌兴奋．收缩偶联发生时，肌膜下出现大量小泡。

Ultrastructural change of subsarcolemic vesicles of the muscle cell during skeletal muscular excitation-contraction coupling

Objective: To study the ultrastructural time-morphological change at millisecond time course level in vesicle beneath the cell membrane of skeletal muscle during muscle excitation-contraction coupling after electrical stimulation. Methods:Two-way infrared detectors with a computer to control the signal of electric stimulation and quick freezing fixation were employed in this test. The thinsection ultrastructure of toad skeletal muscle was studied by transmission electron microscope at 0.0ms, 4.6ms, 24ms after its skeletal muscle was stimulated. The ultrastructure of skeletal muscle at known millisecond time course were observed following quick-freezing after a single electrical stimulation. Results:0.0ms after electrical stimulation, there were only a few sub-sarcolemic vesicles beneath the cell membrane, 4.6ms after electrical stimulation, a large number of vesicles accumulated beneath the cell membrane and most of the vesicles fussed together to form alveolar compositive polymers. 24ms after electrical stimulation, only one or two vesicles have been seen beneath the cell membrane. Conclusion:During muscular excitation-contraction coupling, a large number of alveolus-like sub-sarcolemic vesicles were found beneath the muscle cell membrane.