Averaged and normalized Ig of WT hERG1 channels measured in the presence of extracellular Cd²⁺. (A) Ig measured with test voltages V_t of −60, −30,…+60 mV. The membrane voltage is −110 mV otherwise. (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.