Excitation-contraction coupling in muscle cells is initiated by a restricted membrane depolarization delimited within the neuromuscular junction. This targeted depolarization triggers an action potential that propagates and induces a global cellular calcium response and a consequent contraction. To date, numerous studies have investigated this excitation-calcium response coupling by using different techniques to depolarize muscle cells. However, none of these techniques mimic the temporal and spatial resolution of membrane depolarization observed in the neuromuscular junction. By using optogenetics in C2C12 muscle cells, we developed a technique to study the calcium response following membrane depolarization induced by photostimulations of membrane surface similar or narrower than the neuromuscular junction area. These stimulations coupled to confocal calcium imaging generate a global cellular calcium response that is the consequence of a membrane depolarization propagation. In this context, this technique provides an interesting, contactless and relatively easy way of investigation of calcium increase/release as well as calcium decrease/re-uptake triggered by a propagated membrane depolarization.

中文翻译：

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针对分化的C2C12肌管中的全局钙瞬变的靶向激活的光遗传学方法。

肌肉细胞中的兴奋-收缩偶联是由在神经肌肉接头内定界的受限膜去极化引发的。这种定向的去极化触发了动作电位，该动作电位传播并诱导总体细胞钙反应和随之而来的收缩。迄今为止，许多研究已经通过使用不同的技术使肌肉细胞去极化来研究这种兴奋性钙反应耦合。然而，这些技术都没有模仿在神经肌肉接头中观察到的膜去极化的时间和空间分辨率。通过在C2C12肌肉细胞中使用光遗传学，我们开发了一种技术，用于研究与神经肌肉接头区域相近或较窄的膜表面的光刺激所引起的膜去极化后的钙反应。这些刺激与共聚焦钙成像相结合，产生了整体细胞钙反应，这是膜去极化传播的结果。在这种情况下，该技术提供了一种有趣的，非接触式且相对容易的方法来研究钙的增加/释放以及由传播的膜去极化引发的钙减少/重新摄取。