Fig. 5.

Rapid component of the delayed-rectifier K⁺ current (I_Kr) and basal inward-rectifier K⁺ current (I_K1) in isolated early and late human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). A Representative I_Kr in early (left) and late hiPSC-CM (right). Inset: voltage-clamp protocol. B Maximum tail I_Kr defined as E4031-sensitive current. C Representative recordings of I_K1 in early (left) and late hiPSC-CM (right) during a depolarising ramp pulse protocol (inset). D Peak I_K1 defined as Ba²⁺-sensitive current. E Representative western blots showing the expression of Kir2.1 against CSQ2 (same gel as Fig. 3). F Quantification of Kir2.1 expression relative to early hiPSC-CM (3 independent experiments per group). Data are mean ± SEM. *P < 0.05 ***P < 0.001 versus early hiPSC-CM culture. Symbols represent separate differentiations. n/N = number of hiPSC-CM/differentiation