Effective pumping of blood by the heart depends on complex interactions between electrical and calcium signaling systems within heart cells. Each time the heart beats, current flowing through ion channels in the plasma membrane alters the electrical potential across the cell membrane. This induces the opening of channels selective for calcium, and calcium current crosses the membrane. This current causes the release of a much larger amount of calcium from intracellular stores, a process known as calcium-induced calcium release. This is the key event linking electrical excitation to contraction in the heart.
Despite intensive research efforts, much remains unknown about the regulation of calcium release in healthy heart cells, and how the mis-regulation of this process may contribute to disease states such as heart failure. A key unanswered question concerns the mechanisms underlying the termination of calcium release and the recovery of the release process after termination. I will discuss recent computational and experimental efforts that have addressed this unresolved question and led to a better understanding of the factors that regulate calcium signaling in cardiac cells.