Pharmacological Profile of the Sodium Current in Human Stem Cell-Derived Cardiomyocytes Compares to Heterologous Nav1.5+β1 Model

Figures

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  Figure 1. INa recovery from inactivation: (A) INa recovery from inactivation example traces, chosen from the Nav1.5+β1 model. Currents were elicited with the inactivation recovery pulse protocol as described in material and methods, with horizontal bar at the start indicating the zero current level. Depending on the amount of channels that have been able to recover during the repolarizing step the amplitude of current will increase. (B) Fraction of current recovered, obtained by dividing the amplitude of the recovered current to the maximum current level (I/IMAX), is plotted as a function of the −130-mV prepulse duration (recovery time). Values are mean ± S.E.M. for Nav1.5 (black, n = 5), Nav1.5+β1 (red, n = 5), and hSC-CM (blue, n/#batches = 5/1).

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  Figure 2. Activation and inactivation of INa: (A) Representative INa recordings elicited with the activation pulse protocol (shown below) for Nav1.5, Nav1.5+β1, and hSC-CM. Zero current level is indicated by horizontal bar at the start. (B) INa recordings to determine the voltage-dependence of channel inactivation elicited with the inactivation pulse protocol (shown below). (C) IV curves obtained from analyzing current recordings shown in panel (A). The peak INa currents were normalized to the cell capacitance and plotted as a function of applied potential. Shown values are mean ± SEM for Nav1.5 (black, n = 20), Nav1.5 + β1 (red, n = 15), and hSC-CM INa (blue, n/#batch = 17/4). (D) Voltage dependence of inactivation obtained from analyzing current recordings shown in panel B. Note, coassembly of Nav1.5 with β1 (red circles, n = 15) shifted the voltage dependence of inactivation toward more depolarized potentials compared to Nav1.5 alone (black circles, n = 17). INa of hSC-CM (blue circles, n/#batch = 7/2) inactivated at more depolarized potentials compared to Nav1.5 and Nav1.5+β1. The average voltage dependence of activation, obtained from analyzing the IV curves of panel C, are…

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  Figure 3. Quinidine and ajmaline INa drug response: (A) From left to right representative steady-state INa recordings of Nav1.5, Nav1.5+β1 and hSC-CM upon application of different ajmaline concentrations. Represented conditions are the current amplitudes in absence of drug (control condition, black trace), 3 (red), 10 (blue), and 30 µM (grey) ajmaline, respectively. Currents were elicited by repetitively pulsing to −10 mV as described in material and methods. Starting from the lowest to the highest concentration, every concentration was washed-in until a steady-state effect on the current was observed. Horizontal bar at the start represents the zero current level. (B, C) Concentration-effect curves obtained by plotting the normalized current (I/IMAX) as a function of applied quinidine (panel B) and ajmaline (panel C) concentration, respectively. For each drug the response of the three different models is shown; Nav1.5 (black circles, quinidine n = 8, ajmaline n = 6), Nav1.5+β1 (red circles, quinidine n = 7, ajmaline n = 7), and hSC-CMs (blue circles, quinidine n/#batch = 12/3, ajmaline n/#batch = 8/1).

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  Figure 4. Flecainide INa drug response (A) From left to right representative steady-state INa recordings of Nav1.5, Nav1.5+β1 and hSC-CM elicited at −10 mV depolarization and presence of different flecainide concentrations. Represented conditions are the current amplitudes in absence of drug (control, black trace), 3 (red), 10 (blue), and 30 µM (grey) flecainide, respectively. Horizontal bar indicates zero current level. (B) Concentration-effect curves obtained by plotting the normalized current (I/IMAX) as a function of applied flecainide concentration. The drug response of the three different models are displayed, Nav1.5 (black, n = 16), Nav1.5+β1 (red, n = 14), and hSC-CMs (blue, n/#batch = 15/3).

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  Figure 5. Lidocaine INa drug response (A) From left to right representative steady-state INa recordings of Nav1.5 (left), Nav1.5+β1 (middle), and hSC-CM (right) upon application of different lidocaine concentrations. Represented conditions are the current amplitudes in absence of drug (control, black trace), 10 (red), 30 (blue), and 100 µM (grey) lidocaine, respectively. Zero current level is indicated by the horizontal bar at the start. (B) The response (I/IMAX) to applied lidocaine concentration is shown for the three different models, Nav1.5 (black, n = 7), Nav1.5+β1 (red, n = 10), and hSC-CM (blue, n/#batch = 11/2). Note the difference in the response to lidocaine between Nav1.5 alone and in presence of β1.

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  Figure 6. Phenytoin INa drug response (A) Representative current recordings from Nav1.5 (left), Nav1.5+β1 (middle), and hSC-CM (right) upon application of different phenytoin concentrations. Steady-state current amplitudes are shown for control condition (black), 10 (red), 30 (blue), and 100 µM phenytoin (grey), respectively. Zero current level is indicated by the horizontal bar at the start. (B) Representative current recordings from hSC-CM upon application of different phenytoin concentrations and with a more depolarized prepulse to −90 mV. Steady-state current amplitudes are shown for control condition (black), 10 (red), 30 (blue), and 100 µM phenytoin (grey), respectively. (C) The normalized current (I/IMAX) as a function of applied phenytoin concentration for Nav1.5 (black circle, n = 10), Nav1.5+β1 (red circle, n = 10), and hSC-CMs (blue circle, n/#batch = 12/3). (D) Concentration-effect curves obtained with a more depolarized prepulse (−100 mV for Nav1.5 and −90 mV for Nav1.5+β1 and hSC-CMs) are represented for Nav1.5 (black triangle, n = 5), Nav1.5+β1 (red triangle, n = 5), and hSC-CMs (blue triangle, n/#batch = 8/2). (E) Concentration-effect curves obtained for hSC-CMs at prepulse…