Figure 4. Contribution of the Ca²⁺‐ and P_i‐dependent activation mechanisms to the [Ca²⁺]_cyt dependences in the isolated mitochondrial model .

The basic simulation condition was the same as that of Fig. 2 A. The Ca²⁺‐dependent activation terms of PDHC, ICDH, OGDH, AGC and SN, that is, PDHC A_Ca, ICDH A_Ca, OGDH A_Ca, AGC A_Ca and SN A_Ca, were removed from the mathematical formula individually or at the same time. In addition, the P_i‐dependent activation terms of Complex III and OGDH, that is, C3 A_Pi and OGDH A_Pi, were removed individually or at the same time. A, removal of AGC A_Ca, SN A_Ca and C3 A_Pi. Open circles represent the control model, and filled symbols represent the absence of AGC A_Ca, SN A_Ca and C3 A_Pi. B, summary of the simulation results. Ratios of $\mathrm{m}\dot{V}{}_{{\mathrm{O}}_2}$, NADH and ΔΨ at 10^–6 μm [Ca²⁺]_cyt to those at 0.535 μm [Ca²⁺]_cyt were plotted. Dotted lines indicate the ratios obtained from the control model. –All A_Ca: Ca²⁺‐dependent activation terms were removed from all components; –All A_Pi: P_i‐dependent activation terms were removed from all components.