Figure 3.

Time profile of r_c during slow diastolic depolarization in the SA node model. (A) (Top) Time-dependent changes of V_L (red) and V_m (black). These are the same curves as those shown in Fig. 2A. (Bottom) Time-dependent changes of r_c of the major current components calculated by Eq. 12. (Inset, right bottom) The numerators in Eq. 12 for the corresponding currents. (B) Changes of p(o) or amplitude of the corresponding currents, and [Ca²⁺]_i. It should be noted that the numerical calculation of r_c has poor precision when dV_L/dt approaches 0 because r_c is normalized with dV_L/dt (the denominator in Eq. 12). Therefore, we excluded the ranges in which dV_L/dt is close to zero from the analyses (also done in Figs. 4 and 5).