SCN5A and atrial fibrillation: Ito is an essential component of the early phase of action potential repolarization and plateau potential and can influence the activation of voltage-gated Ca2+ channels, thus balancing the inward and outward currents.41 Similar to Kv1.5, the expression of Kv4.3 was also down-regulated in AF patients.40 In the present study, CUS led to the down-regulations of Nav1.5, Cav1.2, Kv1.5, and Kv4.3 in atria, which may contribute to the occurrence of AF.