Inhibition of cardiac late sodium current (late INa) is a strategy to suppress arrhythmias and sodium-dependent calcium overload associated with myocardial ischemia and heart failure. GS967 is a selective inhibitor of late INa that has been shown to suppress experimentally induced arrhythmias in rabbit myocytes and hearts. It can inhibit A. sulcata toxin II–induced late INa in ventricular myocytes and isolated hearts with IC50 values of 0.13 and 0.21 μM, respectively. GS967 causes minimal inhibition of the delayed-rectifier potassium current nor does it affect L- or T-type calcium channel currents, sodium-calcium exchanger currents, or a panel of 162 receptors, ion channels, transporters, and enzymes.
