Table 1. Pharmacology of the T618I hERG mutant studied with conventional voltage clamp.
Drug | WT IhERG IC50 (µM) | WT IhERG nH | T618I IhERG IC50(µM) | T618I IhERG nH | Fold IC50 |
Quinidine | 0.64 (C.I 0.51–0.79) | 0.65 (C.I 0.55–0.75) | 0.88 (C.I 0.41–1.88) | 0.41 (C.I 0.25–0.57) | 1.4 (0.8–2.4) |
Disopyramide | 7.68 (C.I 6.32–9.34) | 0.87 (C.I 0.66–1.07) | 16.83 (C.I 8.56–33.09) | 0.47 (C.I 0.30–0.64) | 2.2 (1.4–3.5) |
D-Sotalol | 112.2 (C.I 91.7–137.3) | 0.74 (C.I 0.57–0.91) | 356.6 (C.I 305.6–416.1) | 0.85 (C.I 0.70–1.00) | 3.2 (3.0–3.3) |
Flecainide | 1.87 (C.I 1.56–2.25) | 0.81 (C.I 0.68–0.94) | 4.67 (C.I 3.06–7.13) | 0.58 (C.I 0.45–0.71) | 2.5 (2.0–3.2) |
IC50 and nH values shown are derived from fits to concentration-response relations in Figures 5 and 6, obtained from fractional inhibition of IhERG using a voltage step protocol (shown in Figures 5A and 6A). Columns show mean values and 95% confidence intervals (C.I). The right-hand column expresses the ratio of the T618I IC50 to the WT IC50 value, to one decimal place. The numbers in parentheses in the right hand column represent the range of ratio values for the ± C.Is for derived T618/WT IC50s.