Heterogeneous expression of voltage-gated potassium channels in the heart: roles in normal excitation and arrhythmias.

In the mammalian myocardium, there are marked regional differences in action potential waveforms and frequency dependences. This heterogeneity impacts the normal dispersion of ventricular repolarization and appears to reflect the differential expression of voltage-gated K+ channels. Multiple types of voltage-gated K+ currents have been distinguished in mammalian ventricles and, in many cases, the K+ (Kv) channel pore-forming (alpha) and accessory (beta) subunits encoding these channels have been identified. In the diseased myocardium, remodeling of voltage-gated K+ currents occurs, influencing propagation and rhythmicity, effects that can lead to increased dispersion of ventricular repolarization and create substrates for reentrant arrhythmias. Targeting the K+ channels that function to maintain the normal dispersion of ventricular repolarization could be effective in treating cardiac arrhythmias.