Table 1 Biophysical parameters of ML and EHT cultured hiPSC-CM. HiPSC-CM: human induced pluripotent stem cell-derived cardiomyocytes; n: number of cardiomyocytes; I_Na density measured at −30 mV from −110 mV holding potential; V_0.5: voltage of half-maximal (in)activation; k: slope factor of voltage-dependence of (in)activation; τ_fast /τ_slow: fast and slow time constants of recovery from inactivation. Values are mean ± SEM.

Cell capacitance (pF)

23.3 ± 1.9

38

28.2 ± 2.0

37

0.081

I _Na density (pA/pF) at −30 mV test pulse

−10.3 ± 1.2

23

−18.5 ± 1.9

17

<0.001

Inactivation τ (ms) at −30 mV test pulse

1.68 ± 0.1

5

1.73 ± 0.1

9

0.758

Activation

6

9

V_0.5 (mV)

−34.6 ± 2.1

−36.2 ± 0.7

0.353

k_act

5.8 ± 0.2

6.2  ± 0.2

0.187

Steady-state inactivation

10

11

V_0.5 (mV)

−89.8 ± 1.6

−91.3 ± 1.3

0.493

k_inact

6.1 ± 0.5

6.7 ± 0.2

0.252

Recovery of inactivation

8

8

Proportion fast (%)

54.7 ± 14.1

49.7 ± 6.3

0.376

τ _fast (=1/k_fast) (ms)

5.4 ± 1.3

6.7 ± 1.3

0.488

τ _slow (=1/k_slow) (ms)

93.4 ± 17.3

90.4 ± 9.0

0.857