Effect of calcium-activated chloride current blockade on alternans of atrial action potentials: simulation study

Atrial fibrillation (AF) is a common cardiac arrhythmia. The appearance of alternans of atrial action potential (AP) during atrial flutter could play a determinant role as a precursor of AF. The ionic basis for these beat-to-beat changes in AP involves intracellular calcium cycling in the maintenance of alternans. Alterations of intracellular calcium concentration affect to calcium dependent currents like I_NaCa and I_Cl,Ca. In this study, a modified rabbit atrial AP model, that includes I_Cl,Ca formulation, is used. Alternans generation was induced by increasing pace rate (from a cycle length of 1000 to 180 ms). In this situation, our results show that I_Cl,Ca blockade (60% of nominal) inhibits alternans. It suggests that I_Cl,Ca blockade could play an important antiarrhythmogenic role.