The effects of intracellular calcium dynamics on the electrical activity of the cells of the sinoatrial node

We studied the effects of intracellular calcium dynamics on the spontaneous activity of the pacemaker cells using mathematical modeling. We compared the responses to the suppression of L-type calcium currents in several models of the electrical activity of cells of the sinoatrial node. All models showed a decrease in the maximum depolarization rate, the amplitude of action potentials, and the duration of the action potential. The model of the calcium clock showed an increase in the oscillation period by 12%. Models with the spontaneous activity, which is determined by the current activated by hyperpolarization, showed a decrease of the oscillation period by 15%. The comparison of the theoretic results with the experimental data showed that intracellular mechanisms had a different input in the spontaneous activity of pacemakers in the center and periphery of the sinoatrial node.