Data from: Effects of rogue ryanodine receptors on Ca2+ sparks in cardiac myocytes

Ca2+ sparks and Ca2+ quarks, arising from clustered and rogue ryanodine receptors (RyRs), are significant Ca2+ release events from the junctional sarcoplasmic reticulum (JSR). Based on the anomalous subdiffusion of Ca2+ in the cytoplasm, a mathematical model was developed to investigate the effects of rogue RyRs on Ca2+ sparks in cardiac myocytes. Ca2+ quarks and sparks from the stochastic opening of rogue and clustered RyRs are numerically reproduced and agree with experimental measurements. It is found that the stochastic opening Ca2+ release units (CRUs) of clustered RyRs are regulated by free Ca2+ concentration in the JSR lumen (i.e., [Ca2+]lumen). The frequency of spontaneous Ca2+ sparks is remarkably increased by the rogue RyRs opening at high [Ca2+]lumen, but not at low [Ca2+]lumen. Hence, the opening of rogue RyRs contributes to the formation of Ca2+ sparks at high [Ca2+]lumen. The interplay of Ca2+ sparks and Ca2+ quarks has been discussed in details. This work is of significance to provide insight into understanding Ca2+ release mechanisms in cardiac myocytes.由成簇雷诺丁受体（ryanodine receptors, RyRs）与异常雷诺丁受体（rogue RyRs）介导产生的钙火花（Ca2+ sparks）与钙夸克（Ca2+ quarks），是连接肌浆网（junctional sarcoplasmic reticulum, JSR）释放钙离子的重要事件。基于细胞质内钙离子的反常次扩散特性，本研究构建数学模型以探究异常雷诺丁受体对心肌细胞内钙火花的影响。本研究通过数值模拟重现了由异常雷诺丁受体与成簇雷诺丁受体随机开放所产生的钙夸克与钙火花，其结果与实验测量数据吻合良好。研究发现，成簇雷诺丁受体构成的钙释放单元（Ca2+ release units, CRUs）的随机开放，受到连接肌浆网腔游离钙浓度（即[Ca2+]lumen）的调控。当肌浆网腔游离钙浓度较高时，异常雷诺丁受体的开放可显著提升自发性钙火花的发生频率；而在低浓度条件下则无此效应。因此，在高肌浆网腔游离钙浓度环境下，异常雷诺丁受体的开放有助于钙火花的形成。本研究详细探讨了钙火花与钙夸克之间的相互作用，其研究结果对于深入理解心肌细胞内的钙离子释放机制具有重要意义。