Fig. 4. Effects of the high, intermediate, and low Torsades de Pointes risk drugs on the IKr channel in human induced pluripotent stem cell-derived cardiomyocytes.
To elicit the IKr current, a –80 mV holding potential was used, followed by a 2 sec depolarization to +20 mV and a 2 sec repolarization to –40 mV. The IKr currents were isolated by eliminating the ICa currents using 1 μM nifedipine in the external solution. (A) Representative traces demonstrating the effect of sotalol on the IKr channel at 14.69, 44.07, and 146.9 μM. (B) Summary of panel (A) (mean ± SEM, n = 3). (C) Representative traces demonstrating the effect of chlorpromazine on the IKr channel at 0.03, 0.09, and 0.3 μM. (D) Summary of panel (C) (mean ± SEM, n = 4). (E) Representative traces demonstrating the effect of mexiletine on IKr channel at .5, 7.5, and 25 μM. (F) Summary of panel (E) (mean ± SEM, n = 5).
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