FIGURE 6.

EP stability and BP dynamics of the I_K1-removed system during inhibition of I_Ca,L, I_Kr, or I_Ks. (Top) Steady-state I/V relations for g_Ca,L = 0 − 1 (left), g_Kr = 0 − 1 (middle), and g_Ks = 0 − 1 (right), depicted at an interval of 0.2. (Middle, bottom) Bifurcation diagrams with the steady-state (EP1) and stable periodic (MDP, POP) branches (middle), as well as CL (bottom), are shown as functions of g_Ca,L, g_Kr, or g_Ks, which was reduced at an interval of 0.001. The differential equations were numerically solved for 2–3 min at each conductance value. A Hopf bifurcation occurred at g_Ca,L = 0.134 (labeled HB), with the loci of MDP and POP converging at the bifurcation point.