Correlation between human ether‐a‐go‐go‐related gene channel inhibition and action potential prolongation

Figures

• 

  Figure 1. Chemical structures of dofetilide and its derivatives.

• 

  Figure 2. Effects of dofetilide and its derivatives Dofe54 and Dofe33 on AP characteristics in hiPSC‐CMs. Representative AP recordings of hiPSC cardiomyocytes after incubating with dofetilide, n = 4–5 (A), the high affinity derivative Dofe54, n = 4 (B) and the low affinity derivative Dofe33, n = 4 (C) and plots of APD90 as % of control versus concentrations of dofetilide, n = 4–5 (D), Dofe54, n = 4 (E) and Dofe33, n = 4 (F). The data points represent the mean ± SEM (see Table 1) and were fitted by a Hill equation for dofetilide and Dofe54. The data points for Dofe33 were connected by lines.

• 

  Figure 3. Effect of Dofe42, Dofe44 and Dofe45 on AP. (A–C) Representative AP traces of controls and in the presence of the indicated drugs. (D–F) Show dependence of APD90 on the concentration of indicated derivatives (n = 4–6, see Table 1).

• 

  Figure 4. Effect of dofetilide and derivatives on potassium currents mediated through hERG channels expressed in HEK293 cells. (A) Representative current traces of control current (in the absence of drug) and in the presence of Dofe54 after steady state was reached at each concentration applied. The voltage protocol illustrated was applied every 3 s (A, upper panel). (B) Concentration‐inhibition curves for dofetilide (n = 5) and high affinity derivatives: Dofe54 (n = 5), Dofe81 (n = 6), Dofe60 (n = 5), Dofe78 (n = 7), Dofe35 (n = 8), Dofe45 (n = 5) and Dofe44 (n = 6). (C) Concentration‐inhibition curves for dofetilide and low affinity derivatives: Dofe33 (n = 6), Dofe31 (n = 7), Dofe30 (n = 7), Dofe41 (n = 8), Dofe42 (n = 8) and Dofe43 (n = 5). Peak tail current values (mean ± SEM, see Table 2) were fitted by the Hill equation.

• 

  Figure 5. Correlation between D150 (concentration that prolongs AP in hiPSC‐CM by 50%) and IC50 (half‐maximal concentration inhibiting hERG channels in HEK293 cells). A significant linear correlation (r = 0.94, P < 0.05) was observed for 12 data points (black circles) including dofetilide and 11 derivatives. Derivatives Dofe45, Dofe44 and Dofe42 (red circles) were not included in the correlation analysis. Dofe45 prolonged the AP in hiPSC‐CM by 50% only at 538 nM and Dofe42 and 44 at >600 nM. The red line represents a prediction of the mathematical simulation of the hiPSC‐CM's AP (see Figure 8).

• 

  Figure 6. Inhibition of Cav1.2 channel by dofetilide derivatives. (A) Superimposed barium currents through rabbit Cav1.2 in control (black) and in the presence of indicated concentrations of Dofe42 (left), Dofe44 (middle) and Dofe45 (right). Barium currents were recorded in response to 50 ms pulses (0.2 Hz) from the holding potential of −80 to +10 mV. (B) Concentration‐dependence of peak IBa inhibition by Dofe42 (IC50 = 38 ± 9.3 μM, n = 5, left), Dofe44 (IC50 > 200 μM, n = 5, middle) and Dofe45 (IC50 = 192 ± 28 nM, n = 5, right). The IC50 values were obtained by fitting the data by the Hill equation. (C) Barium currents through Cav1.2 during 1 Hz trains of 50 ms pulses from −80 to +10 mV under control conditions (absence of drug) and after 3 min incubation in the presence of the indicated concentrations of dofetilide derivatives. The first current in drug reflects the resting state inhibition. (D) Mean peak current amplitudes during 50 ms pulse trains in control and the presence of the indicated concentration of Dofe42, Dofe44 and Dofe45. The peak current decay after 20 pulses at 1 Hz in control indicates the development of inactivation. Peak current decay in the presence of Dofe42 (100…

• 

  Figure 7. Inhibition of Nav1.5 by dofetilide derivatives. (A) Superimposed INa through human Nav1.5 in control (black) and in the presence of indicated concentrations of Dofe42 (left), Dofe44 (middle) or Dofe45 (right). Sodium currents were recorded in response to 20 ms pulses (0.2 Hz) from a holding potential of −140 to −10 mV. (B) Concentration‐dependence of peak INa inhibition at a holding potential of −140 mV (squares) and −80 mV (circles) yielding IC50 values for Dofe 42 of IC50 = 77.9 ± 9.7 (at −140 mV, n = 6) and IC50 = 13.8 ± 1.9 (at −80 mV, n = 5), Dofe 44 of IC50 = 23.3 ± 1.9 (at −140 mV, n = 6) and IC50 = 4.7 ± 2.0 (at −80 mV, n = 6) and Dofe 45 of IC50 = 69.7 ± 1.0 (at −140 mV, n = 6) and IC50 = 6.4 ± 1.0 μM (at −80 mV, n = 5).

• 

  Figure 8. Simulation of hiPSC‐CM AP at indicated levels of hERG, Cav1.2 and Nav1.5 channel inhibition. (A) Simulation of hiPSC‐CM APs for different levels of selective hERG channel inhibition. (B) Dependence of the calculated APD90 (as % of control) on the concentration of a selective hERG channel inhibitor. (C) Simulated APs at a Dofe45 concentration of 300 nM accounting for hERG inhibition (IC50 = 40 nM) and simultaneous inhibition of Cav1.2 (IC50 = 200 nM) and Nav1.5 (IC50 = 8.9 μM). (D) Comparison of simulated APs at different IC50s of Cav1.2 and Nav1.5 inhibition. Control AP is shown in dark blue and AP for selective hERG channel inhibition (IC50 = 40 nM) in light blue. Red 100 nM (Cav1.2) and 1 μM (Nav1.5), orange 100 nM (Cav1.2) and 10 μM (Nav1.5), magenta 500 nM (Cav1.2) and 1 μM (Nav1.5), green 500 nM (Cav1.2) and 10 μM (Nav1.5). See also Supporting Information Table S1 comparing the values used in silico AP models of adult ventricular myocytes and hiPSC‐CM.