Fig. 9.
Block of S620T and S620T+Y652W mutant hERG1 channels at a test potential of −30 mV. (A–C) Concentration-response relationships for block of Itest at −30 mV for S620T (▾) and S620T+Y652W (▴) mutant hERG1 channels by cisapride (n = 3–4), dofetilide (n = 4), and MK-499 (n = 3) as indicated. Data were fitted with a logistic equation (smooth curves). (D) Comparison of the fold increase in IC50 value for block of S620T channels compared with block of S620T+Y652W channels when Itest was measured at 0 mV or −30 mV for individual drugs as indicated.