The current–voltage relations of the ion currents in the E9-E11 mouse cardiomyocytes and in the mathematical model. (A) I_NCX, (B) I_f (the activation time constant is also shown), (C) I_Na, (D) I_K1 and I_KDR, and (E) T- and L-type calcium channels (top right panel). In each case, red or blue symbols denote the experimentally defined features of the ion currents that were adopted into the model (black solid lines). The representative recordings are shown in the left column of each panel.