Na⁺ channel currents in response to adult ventricular action potential waveforms. (A and B) Adult ventricular action potential waveforms were computed (ten Tusscher et al., 2004) and applied as command waveforms in whole-cell voltage-clamp mode on iPSC-CMs from father (A) and proband (B) using recording solutions to reveal Na⁺ channel currents. Mexiletine-dissected Na⁺ channel currents are shown, averaged for four (A) and five (B) cells.