骨骼肌兴奋收缩偶联时肌浆网膜Ca2+通道的研究

目的：从毫秒级功能变化水平实时观察骨骼肌肌浆网、T-管在收缩潜伏期内超微结构的时相—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，采用透射电镜对骨骼肌在电刺激后0．8ms，2ms，4．6ms，10．8ms和18．4ms的超微结构变化进行观察。结果：刺激0．8ms后，肌浆网和T-管未见明显改变。刺激2ms后，SR内出现电子密度较大的物质。刺激4．6ms后，肌浆网膜内外侧可见一一对应的电子密度大的物质。刺激10．8ms后，SR与T-管形态又恢复原状,SR内电子密度大的物质消失。结论：骨骼肌兴奋-收缩偶联发生时，肌浆网的形态发生改变，肌浆网内出现电子密度较大的物质且逐渐向靠近T-管的方向移动。

Research on Ca2+ channels of SR at skeletal muscular excitation-contraction coupling

Obiective: To study the ultrastructural time-morphological changes at millisecond time course level in sarcoplasmic reticulum (SR) and T-tube of skeletal muscle during 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 ultrastructure of toad skeletal muscle was observed by transmission electron microscopy after its skeletal muscle was stimulated in 0.8 ms, 2 ms, 4.6 ms, 10.8 ms, 18.4 ms respectively. The skeletal muscular ultrastructure at known millisecond time course were observed following quick-freezing after a single electrical stimulation. Results: At 2 ms after electrical stimulation, many deep density substance appeared in SR, and some homologous deep density substance appeared along the two faces of sarcoplasmic reticulum membrane at 4.6 ms after electrical stimulation. But after 10.8 ms, the shapes of SR regained. Conclusion: During excitation-contraction coupling, the shape of SR changed, some homologous deep density substance in SR emerged and moved to T-tube.