Fig. 5

Inward rectifier K⁺ currents (I_K1) and ACh-activating K⁺ currents (I_K,ACh) in P19CL6-derived cardiomyocytes and P19CL6-Csx-derived cardiomyocytes. Current–voltage relationships of I_K1 (a, b) and I_K,ACh (c, d). Scales of insets: 50 ms and 200 pA for I_K1, 50 ms and 500 pA for I_K,ACh. I_K1 currents were elicited by hyperpolarizing and depolarizing pulses from a holding potential of ‒ 40 mV to the test potentials between ‒ 110 and + 20 mV (10 mV increments). Each inset shows representative current traces at ‒ 110 mV before (white up-pointing triangle) and after (black up-pointing triangle) application of 200 µmol L⁻¹ Ba²⁺. I_K,ACh was elicited by hyperpolarizing and depolarizing pulses from a holding potential of ‒ 50 mV to the test potentials between ‒ 120 and + 40 mV (20 mV increments). Each inset shows representative current traces at ‒ 120 mV before (white up-pointing triangle) and after (black up-pointing triangle) application of 20 µmol L⁻¹ carbachol. *p < 0.05 compared with P19CL6 cells in the early stage, and ^†p < 0.05 compared with P19CL6-Csx cells in the early stage