Figure 2. Comparison of Model Simulations to Experimental Data on NADH, MV_O2, Cytochrome C Redox, and Matrix pH for Model without Phosphate Control.

(A) Results for normalized matrix NADH as a function of buffer inorganic phosphate concentration are shown for the two experimental cases of resting mitochondria ([ADP]_e = 0, state 4) and active state mitochondria ([ADP]_e = 1.3 mM, state 3).

(B) Results for MV_O2 (rate of oxygen consumption) are shown for the same experimental cases as in (A). Experimental data are not available for the resting state, in which a minimal flux through the electron transport system is maintained to compensate for cation flux across the inner membrane.

(C) Results for cytochrome C reduced fraction are shown for the experimental cases as in (A). The black curves correspond to the model equations developed in the text. The red curves correspond to the best-fit model simulations obtained with equation 9 modified to not include the factor [cytC(red)²⁺]/cytC_tot multiplying the expression for J _C4.

(D) Matrix pH (model-simulated and experimentally measured) is plotted as a function of buffer phosphate for the experimental cases as in (A).

All computed results in this figure correspond to steady-state simulations of model described under “Mitochondrial Model without Phosphate Control.” Model simulations for [ADP]_e = 1.3 mM, and [ADP]_e = 0 mM are plotted as solid lines and dashed lines, respectively. Experimental data (circles and triangles) are obtained from [10].