Figure 4:

Action potentials of SCN5A WT and R1193Q in hiPS-CMs. A-B) Action potentials generated by stimulating hiPS-CMs derived from an unaffected individual at 0.5 and 0.1 Hz. C) Action potentials from SCN5A R1193Q edited otherwise isogenic control stimulated at 0.5 Hz as in A. Action potentials are much longer for R1193Q than the unedited control line. D) Cells could not be stimulated at 0.1 Hz due to spontaneous beats. Arrhythmogenic DADs were also observed in the absence of AP stimulation. E) Long action potential phenotype observed in R1193Q hiPS-CMs can be rescued by addition of PIP₃, a known late current modulator.