Pinçon-Raymond M, García L, Romey G, Houenou L, Lazdunski M, Rieger F
INSERM U.153-CNRS UA.614, Moulin, Paris.
J Physiol (Paris). 1990;84(1):82-7.
Excitation-contraction in muscle fibers are coupled through a complex mechanism involving multiproteic components located at a specialized cellular site, the triadic junction. Triads in normal muscle fiber result from the apposition of sarcoplasmic reticulum citernae and T-tubule and possess strikingly organized ultrastructural elements, bridging both types of membranes, the "junctional feet". Muscular dysgenesis in the mouse is characterized by total muscle inactivity in the developing skeletal muscles due to excitation-contraction uncoupling. Triads have been found to be disorganized with no "junctional feet" and dihydropyridine (DHP) binding sites are decreased with no slow Ca2+ currents, suggesting a basic defect in the excitation-contraction coupling machinery itself. We may hypothesize that muscular dysgenesis results in a marked defect in a functional protein involved in the morphogenesis of the triad and/or directly involved in Ca2+ release for contraction.
肌肉纤维中的兴奋-收缩偶联是通过一种复杂机制实现的，该机制涉及位于特殊细胞位点——三联体连接处的多种蛋白质成分。正常肌肉纤维中的三联体是由肌浆网池与T小管并列形成的，具有显著有序的超微结构元件，即连接足，它横跨两种类型的膜。小鼠的肌肉发育不全表现为，由于兴奋-收缩解偶联，发育中的骨骼肌完全无法活动。已发现三联体结构紊乱，没有“连接足”，二氢吡啶（DHP）结合位点减少，且没有慢钙电流，这表明兴奋-收缩偶联机制本身存在基本缺陷。我们可以推测，肌肉发育不全导致参与三联体形态发生的功能性蛋白质出现明显缺陷，和/或直接参与收缩时钙释放的功能性蛋白质出现明显缺陷。
