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 detail. This work is of significance to provide insight into understanding Ca2+ release mechanisms in cardiac myocytes.

Ca²⁺火花（Ca²⁺ sparks）与Ca²⁺夸克（Ca²⁺ quarks）分别源自成簇兰尼碱受体（ryanodine receptors, RyRs）与异常兰尼碱受体，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Ca²⁺的异常亚扩散特性，本研究构建数学模型以探究异常兰尼碱受体对心肌细胞内Ca²⁺火花的调控效应。本研究通过数值模拟复现了由异常兰尼碱受体与成簇兰尼碱受体随机开放所产生的Ca²⁺夸克与Ca²⁺火花，该结果与实验观测数据高度一致。研究发现，成簇兰尼碱受体的钙释放单元（Calcium release units, CRUs）的随机开放，受连接肌浆网管腔内游离Ca²⁺浓度（即[Ca²⁺]lumen）的调控。在高[Ca²⁺]lumen条件下，异常兰尼碱受体的开放可显著升高自发性Ca²⁺火花的发生频率；而在低[Ca²⁺]lumen条件下则无此效应。由此可见，在高[Ca²⁺]lumen环境中，异常兰尼碱受体的开放可促进Ca²⁺火花的形成。本研究还详细探讨了Ca²⁺火花与Ca²⁺夸克之间的相互作用。本研究为深入解析心肌细胞内的钙离子释放机制提供了重要见解。