Ca Sparks Do Not Explain all Ryanodine Receptor-Mediated SR Ca Leak in Mouse Ventricular Myocytes
Ca Sparks Do Not Explain all Ryanodine Receptor-Mediated SR Ca Leak in Mouse Ventricular Myocytes
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DOI：
10.1016/j.bpj.2010.01.042
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发表时间：
2010-05-19
影响因子：
3.4
通讯作者：
Shannon, Thomas R.
中科院分区：
文献类型：
--
作者：
Santiago, Demetrio J.;Curran, Jerald W.;Shannon, Thomas R.
心室肌细胞肌浆网 (SR) 的舒张期 Ca 泄漏降低了 SR Ca 含量，从而稳定了下一次心跳的 SR Ca 释放通道兰尼碱受体的活性。 SR Ca 泄漏已使用全细胞荧光进行全局可视化，或使用共聚焦显微镜进行局部可视化，但从未同时使用这两种方法。当使用共聚焦显微镜时，泄漏被成像为“Ca火花”，这是由释放的Ca和胞质指示剂的局部反应扩散产生的荧光物体。在这里，我们使用共聚焦显微镜，同时测量了完整小鼠心室肌细胞中整体兰尼碱受体介导的渗漏率（J（leak））和Ca spars。我们发现火花频率和 J（泄漏）是相关的，正如预期的那样，如果两者都是常见现象的表现。然而，我们还发现火花解释了大约一半的 J(leak)。我们的策略揭示了潜在生理相关性的次分辨率（即非火花）释放的存在。
Diastolic Ca leak from the sarcoplasmic reticulum (SR) of ventricular myocytes reduces the SR Ca content, stabilizing the activity of the SR Ca release channel ryanodine receptor for the next beat. SR Ca leak has been visualized globally using whole-cell fluorescence, or locally using confocal microscopy, but never both ways. When using confocal microscopy, leak is imaged as "Ca sparks," which are fluorescent objects generated by the local reaction-diffusion of released Ca and cytosolic indicator. Here, we used confocal microscopy and simultaneously measured the global ryanodine-receptor-mediated leak rate (J(leak)) and Ca spars in intact mouse ventricular myocytes. We found that spark frequency and J(leak) are correlated, as expected if both are manifestations of a common phenomenon. However, we also found that sparks explain approximately half of J(leak). Our strategy unmasks the presence of a subresolution (i.e., nonspark) release of potential physiological relevance.