Gomez J P, Potreau D, Raymond G
Laboratory of General Physiology, URA CNRS 290, Faculty of Sciences, Poitiers, France.
Cell Calcium. 1994 Apr;15(4):265-75. doi: 10.1016/0143-4160(94)90066-3.
Resting and transient levels of intracellular free calcium concentrations were recorded in indo-1 loaded neonatal rat ventricular cardiomyocytes in primary culture by means of an interactive laser cytometer. The calcium transients were induced by high potassium and caffeine applications. The resting level of intracellular calcium remained constant (about 140 nM) throughout the culture (up to 7 days). The calcium transients induced by 100 mM K+ changed during culture from a low, cobalt sensitive response at 2 days, to a strong biphasic response at 7 days. At 2 days the response was fully blocked by cobalt. At 7 days the transient phase was abolished by cobalt and ryanodine, whereas the second sustained phase was only partially blocked. The calcium transient induced by caffeine was present as early as the first days, and increased with the age of the culture. This transient was blocked by ryanodine. The calcium influx through sarcolemmal calcium channels could be responsible for intracellular calcium transients in 2 day-old cells, whereas in 7 day-old cells, they seem to be only the trigger for sarcoplasmic reticulum calcium release via a mechanism such as 'calcium-induced calcium-release'. Other mechanisms, such as the sodium-calcium exchange mechanism activated by sarcolemmal depolarisation, seem to be implicated too and therefore could explain the sustained level of intracellular calcium during 100 mM K+ stimulation. The developmental changes through differentiation and maturation of myocytes in culture could account for the age dependent evolution of the responses obtained. From these results it is possible to conclude that calcium movements implicated in the excitation-contraction coupling mechanism in the development of rat neonatal cardiomyocytes are similar in primary culture and in the postnatal period in vivo.
通过交互式激光细胞仪记录原代培养的indo-1负载新生大鼠心室心肌细胞内游离钙浓度的静息水平和瞬态水平。钙瞬变由高钾和咖啡因诱导产生。在整个培养过程（长达7天）中，细胞内钙的静息水平保持恒定（约140 nM）。100 mM K⁺诱导的钙瞬变在培养过程中从第2天的低钴敏感性反应，变为第7天的强烈双相反应。在第2天，该反应被钴完全阻断。在第7天，瞬态期被钴和兰尼碱消除，而第二个持续期仅被部分阻断。咖啡因诱导的钙瞬变最早在培养的第一天就出现，并随着培养时间的延长而增加。该瞬变被兰尼碱阻断。在2日龄细胞中，通过肌膜钙通道的钙内流可能是细胞内钙瞬变的原因，而在7日龄细胞中，它们似乎只是通过“钙诱导钙释放”等机制触发肌浆网钙释放的因素。其他机制，如肌膜去极化激活的钠钙交换机制，似乎也有牵连，因此可以解释在100 mM K⁺刺激期间细胞内钙的持续水平。培养的心肌细胞通过分化和成熟的发育变化可以解释所获得反应的年龄依赖性演变。从这些结果可以得出结论，在原代培养和体内出生后时期，大鼠新生心肌细胞发育过程中兴奋-收缩偶联机制中涉及的钙运动是相似的。
