Modeled Ig of WT hERG1 channels. (A) Ig in response to the voltage-clamping protocol used in Fig. 12. (B and C) Ig_ON at 0–10 ms and 10–300 ms, respectively. (D and E) Ig_OFF at 300–310 ms and 310–600 ms, respectively. (F) The initial phase (0–1 ms) of Ig_ON is primarily carried by the fast transition between S₀ and S₁. (G) The slow decay of Ig_ON between 2 and 10 ms is caused by a mixture of increasing and decreasing gating currents associated with the slow transitions in the gating model.