Atrial-ventricular differences in rabbit cardiac voltage-gated Na+ currents: Basis for atrial-selective block by ranolazine

Differences exist between rabbit atrial and ventricular myocytes in the biophysical properties of INa. The more negative voltage dependence of INa activation and inactivation, together with trapping of the drug in the inactivated channel, underlies an atrial-selective action of ranolazine.