Fig. 6.

Comparative effects on To042 and mexiletine on hERG potassium channel. (A) Representative traces of hERG potassium currents recorded in transfected tsA201 cells at steady-state before (CTRL) and during application of 100 μM mexiletine (left panel) or 10 μM To042 (right panel). The cells were held at −70 mV and depolarized for 5 s to potentials ranging from −70 to +70 mV, applied in 10 mV increments. Tail currents were recorded at −50 mV. (B) Current-voltage relationships were drawn from steady-state current amplitudes measured at the end of the 5 s-long test pulse, before and during application of various mexiletine (left panel) and To042 concentrations (right panel). Each experimental relationship is the mean ± S.E.M. of at least 3 cells. (C) Concentration-response relationships drawn using tail current amplitudes measured at −50 mV after test depolarization at −10 mV. Each data point is the mean ± S.E.M. from at least 3 cells. The relationships were fit to the first-order binding equation (1) and fit parameter values are reported in the text.