Ryanodine Receptors Coupling Causes a Calcium Leak in Cardiac Cell

Here we introduce results of a mathematical modeling of calcium sparks in cardiac cells. We developed a model of the calcium release unit which includes a single sarcoplasmic reticulum (SR) lumen, a regular 9×9 cluster of RyRs and a dyadic space. 2D diffusion problem of Ca2+ ions across the dyadic space was solved thereby we reproduced Calcium-fnduced-Calcium-Release (CICR) effect and domino-like RyRs activation in the cluster. We take into account allosteric and Ca²+-induced coupling between RyRs. We show, that coupling between RyRs leads to the stability of Ca²⁺ sparks in amplitude and frequency. However, a sudden stop of spontaneous Ca²⁺ releases can be a result of strong allosteric coupling between RyRs.