D202N eliminates I_Ks during a simulated cardiac AP. Typical currents recorded at 35°C from cells expressing WT (B) or D202N KCNQ1+KCNE1 (C) channels during a ventricular AP clamp (duration of 230 ms; LabHeart version 4.9.5) (A) applied at 2 Hz. (D) Charge from integrated current waveforms during the AP protocol compared between WT and D202N I_Ks. Data were normalized to the total charge during the first AP. Currents recorded during 4-Hz ventricular AP clamp to WT (E) or D202N (F) cells. (G) Charge movement at 4 Hz was quantitated as in D. Total charge from D202N channels was significantly reduced compared with WT channels, at both 2 and 4 Hz (P < 0.001).