Simultaneous recordings of action potentials and calcium transients from human induced pluripotent stem cell derived cardiomyocytes

Figures

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  Fig. 1.. Representative immunofluorescence images of hiPSC-CMs showing cardiac proteins. (Upper) 50 slices were combined from confocal immunofluorescence images of nucleus (DAPI, blue), cardiac troponin T (cTnT, green) and cardiac ryanodine receptors (RyR2, red). Final panel shows the former three merged. (Lower) 40 slices were combined from confocal immunoflurescence images of nucleus (DAPI, blue), cTnT (green), L-type calcium channels (CaV1.2, red). Final panel shows the former three merged. Scale bars: 10 µM.

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  Fig. 2.. Representative voltage-gated ionic current traces from hiPSC-CMs and their predominance area in action potential. Ito, transient outward potassium current; ICa, calcium current; INa, sodium current; IKr/IKs, rapid/slow rectifier potassium current; If, funny current; IK1, inward rectifier potassium current. See Fig. S1 for current-voltage relationship of respective ionic currents.

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  Fig. 3.. Simultaneous recording of action potentials and intracellular calcium recording in hiPSC-CMs. (A-C) Representative traces of action potentials (black, upper traces) and corresponding CaTs (red, lower traces) recorded simultaneously in (A) ventricular-like, (B) atrial-like and (C) nodal-like hiPSC-CMs. Dashed lines represent 0 mV. (D-F) Action potential amplitudes and CaT amplitudes were normalized to 1.5 and 1 value respectively. Ventricular-like hiPSC-CMs, N=37; atrial-like hiPSC-CMs, N=2; nodal-like hiPSC-CMs, N=2.

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  Fig. 4.. Correlation between action potential and calcium transient parameters in ventricular-like hiPSC-CMs. (A-C) The linear relationship between (A) APD90 and CaT90, (B) APD50 and CaT50 and (C) APD50 and time-to-peak. N=37, n=583, P<0.0001, Pearson’s correlation test. AP parameters were compared with their corresponding CaT parameters.

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  Fig. 5.. Membrane potentials and the corresponding calcium transient during arrhythmia in hiPSC-CMs. (A) Action potentials exhibiting DADs (black, upper trace) with corresponding elevation in CaT (red, lower trace). (B) Action potentials exhibiting DADs (black, upper trace) without corresponding elevation in CaT (red, lower trace). For more detail, see Fig. S2. (C) Action potentials exhibiting phase 3 EAD (black, upper trace) and corresponding CaT (red, lower trace). Note the elevation in intracellular calcium level in phase 3 EAD. (D-F) Action potential amplitudes and CaT amplitudes were normalized to 1.5 and 1 value respectively. Dashed lines represent 0 mV. Red arrowheads indicate the DADs and phase 3 EADs.

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  Fig. 6.. Effect of 5 µM Nimodipine in spontaneous beating of hiPSC-CMs. (A) Baseline recording of action potentials (black, upper trace) and corresponding CaT traces (red, lower trace) from the same hiPSC-CMs. (B) Representative traces of membrane potential (black, upper trace) and CaT (red, lower trace) showing the cessation of spontaneous beating with blockage of calcium channels. (C,D) Action potential amplitudes and CaT amplitudes were normalized to 1.5 and 1 value respectively. Dashed lines represent the 0 mV. (N=3).

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  Fig. 7.. Three different responses of 650 nM E-4031 in spontaneous beating of hiPSC-CMs. (A) Representative traces of baseline action potential (black, upper trace) and corresponding CaT (red, lower trace). (B) Prolongation of action potential duration (black, upper trace) and corresponding CaT (red, lower trace). (C) Occurrence of phase 2 EAD (black, upper trace) and corresponding CaT (red, lower trace). (D) Oscillation of membrane potential with EADs (black, upper trace) corresponding with CaT (red, lower trace). (E-H) Action potential amplitudes and CaT amplitudes were normalized to 1.5 and 1 value respectively. Dashed lines represent the 0 mV. Red arrowheads indicate the phase 2 and phase 3 EADs.