Real Time Researches On Morphological Changes In Skeletal Muscle During Excitation-contraction Coupling

The real time morphological changes and release of calcium ions from sarcoplasmic reticulum in skeletal muscle during excitation-contraction coupling are the most attractive research field and also the most difficulty one.In this paper, the ultrastructural changes in skeletal muscle at some defined time points during excitation-contraction coupling were studied by computer controlled electrical stimulation-real time cryofixation freeze substitution and electron microscope. Besides, the ultrastructural changes of skeletal muscle and the possible mechanism of calcium release during excitation-contraction coupling were analysed and discussed, respectively. The results revealed that: 1) In the skeletal muscle which fixated by real time cryofixation, the ultrastructure conserved perfectly and clearly observable. 2) During excitation-contraction coupling, the triad ultrastructure in skeletal muscle real time changed as following.3) During excitation-contraction coupling, there appeared large amount of alveolus below cell membrane: 4.6 ms after electrical stimulation, below cell membrane there appeared large amount of alveolus which inclined to merge and formed 3-8 alveolus composed polymer; 24ms after electrical stimulation, alveolus disappeared, only remained a few alveolus below cell membrane.The results suggest that during excitation-contraction coupling, a large number of alveolus appear below cell membranes. These vesicles are likely to result in the local calcium ion concentration increase within cell, which might be the reason of Ca2+ :sparckle. Therefore the cryofixation method can produce excellent ultrastructural preservation and the real time processed electrical stimulation-cryofixation methods allow the study of the real time ultrastructural changes related to dynamic process...