Cognard C, Constantin B, Rivet-Bastide M, Raymond G
Laboratoire de Physiologie Générale URA CNRS 290, Université de Poitiers, France.
Cell Calcium. 1993 Apr;14(4):333-48. doi: 10.1016/0143-4160(93)90054-a.
Resting intracellular calcium levels and intracellular calcium transients induced by three types of stimulus (acetylcholine, high potassium and caffeine) were recorded, during in vitro myogenesis, by means of a ratiometric fluorescence method using the calcium probe Indo-1 under laser illumination. Resting levels seemed to decrease with the age of cultured cells and the depolarization-induced transients, through 100 mM K+ or Ach application, were progressively faster and larger as the muscle cells developed. An additive mechanism, likely due to calcium entry into the cell through nicotinic acetylcholine receptors, could explain the differences observed in Ach-induced responses as compared with the 100 mM K(+)-induced ones. In myoballs (the older cells) the calcium transients exhibited progressively a biphasic shape. From data obtained in different conditions (tetrodotoxin, nifedipine, strontium and free Ca EGTA) and those indicating the appearance of caffeine-releasable intracellular calcium stores only at 2-3 days stage, and from the previously reported developmental appearance of calcium currents and contraction, it was proposed that, in young myotubes, the calcium transients were more dependent on extracellular calcium than in older cells. These developmental data are discussed in the light of a known model of the in situ biogenesis of the structures involved in excitation-contraction coupling (ECC) like transverse tubules and triads.
在体外成肌过程中，使用钙探针Indo-1，通过激光照射下的比率荧光法记录了三种刺激（乙酰胆碱、高钾和咖啡因）诱导的静息细胞内钙水平和细胞内钙瞬变。静息水平似乎随着培养细胞的年龄而降低，并且通过施加100 mM K⁺或乙酰胆碱诱导的去极化诱导的瞬变随着肌肉细胞的发育而逐渐更快、更大。一种可能由于钙通过烟碱型乙酰胆碱受体进入细胞的加和机制，可以解释与100 mM K⁺诱导的反应相比，在乙酰胆碱诱导的反应中观察到的差异。在肌球（较老的细胞）中，钙瞬变逐渐呈现双相形状。从在不同条件下（河豚毒素、硝苯地平、锶和游离Ca-EGTA）获得的数据以及那些仅在2-3天阶段表明出现咖啡因可释放的细胞内钙储存的数据，以及从先前报道的钙电流和收缩的发育出现情况来看，有人提出，在年轻的肌管中，钙瞬变比在较老的细胞中更依赖细胞外钙。根据已知的参与兴奋-收缩偶联（ECC）的结构如横管和三联体的原位生物发生模型，对这些发育数据进行了讨论。
