Figure 1.
Effect of PD-118057 (3 µM) on voltage-dependent activation of hERG channel.
Inset shows the voltage clamp protocol. a-f: Representative current traces in HEK293 cells transfected with WT-hERG, WT/E637K-hERG, and E637K-hERG in the presence or absence of PD-118057. g, h: Current-voltage (I-V) relationships for peak and tail current amplitudes of WT-hERG and WT/E637K-hERG transfected cells in the presence and absence of PD-118057. i: Amplitudes of tail currents of WT-hERG and WT/E637K-hERG channels in the presence or absence of PD-119057 are plotted as a function of the test potential and fitted to a Boltzmann function (n = 6).
Figure 2.
Effect of thapsigargin (1 µM) on voltage-dependent activation of hERG channel.
Inset shows the voltage clamp protocol. a-f: Representative current traces in HEK293 cells transfected with WT-hERG, WT/E637K-hERG, and E637K-hERG in the presence or absence of thapsigargin. g, h: Current-voltage (I-V) relationships for peak and tail current amplitudes of WT-hERG and WT/E637K-hERG transfected cells in the presence or absence of thapsigargin. i: Amplitudes of tail currents of WT-hERG or WT/E637K-hERG channels in the presence or absence of thapsigargin are plotted as a function of the test potential and fitted to a Boltzmann function (n = 6).
Figure 3.
Effect of PD-118057 (3 µM) and thapsigargin (1 µM) on steady-state inactivation of hERG channel.
Inset shows the voltage clamp protocol. a-d: Representative current traces in HEK293 cells transfected with WT-hERG or WT/E637K-hERG plasmids in the presence or absence of PD-118057 and thapsigargin. e: Normalized steady-state inactivation curves in cells transfected with WT-hERG or WT/E637K-hERG plasmids in the presence or absence of drug (n = 6).
Figure 4.
Effect of PD-118057 (3 µM) and thapsigargin (1 µM) on time courses of inactivation of hERG channel.
Inset shows the voltage clamp protocol. a-d: Representative current traces of time courses and inactivation time constants (tau, τ) in HEK293 cells transfected with WT-hERG or WT-hERG/E637K-hERG plasmids in the presence or absence of PD-118057 and thapsigargin. e: τ was measured by fitting inactivation currents of WT-hERG or WT-hERG/E637K-hERG channel, in the presence or absence of PD-118057 and thapsigargin during test pulse at each potential, with a single exponential function (n = 6).
Figure 5.
Effect of PD-118057 (3 µM) and thapsigargin (1 µM) on recovery from inactivation of hERG channel.
Insert shows the voltage clamp protocol. a-d: Representative recovery from inactivation traces in HEK293 cells transfected with WT-hERG or WT/E637K-hERG plasmids in the presence or absence of PD-118057 and thapsigargin. e: Time constants (tau, τ) for hERG channel recovery from inactivation are plotted as a function of test voltages for WT-hERG or WT/E637K-hERG plasmids in the presence or absence of drug (n = 6).
Figure 6.
Effect of PD-118057 (3 µM) and thapsigargin (1 µM) on deactivation of hERG channel.
Insert shows the voltage clamp protocol. a-d: Representative deactivation traces in HEK293 cells transfected with WT-hERG or WT/E637K-hERG in the presence or absence of PD-118057 and thapsigargin (arrow marks the deactivation phase). e: Fast and slow components of deactivation time constants (tau, τ) are plotted as a function of test potentials for WT-hERG or WT/E637K-hERG plasmids in the presence or absence of drug (n = 6).
Figure 7.
Analysis of hERG protein expression in HEK293 cells.
a. Representative protein expression of untreated WT-hERG, WT/E637K-hERG, and E637K-hERG channels. b–d. Representative protein expression of WT-hERG, WT/E637K-hERG and E637K-hERG channels treated with 1 uM thapsigargin for 24 h to 48 h, respectively. Thapsigargin has no effect on the protein expression profile of either WT/E637K-hERG or E637K-hERG. e–f. Representative protein expression of WT-hERG, WT/E637K-hERG and E637K-hERG channels treated with 3 µM PD-118057 for 24 h to 48 h, respectively. As demonstrated, PD-118057 also has no effect on the protein expression profile of either WT/E637K-hERG or E637K-hERG channels.