FIGURE 4.

Relationship between mitochondrial inner membrane potential and the respiratory flux. The rate of the electron transport chain and the ΔΨ_m are modulated through the concentration of electron carriers (ρ^res) (A, B). A steady-state analysis of the whole model behavior is performed. The parameters utilized in the simulations are those reported in Table 3 and as follows: P_i = 20.0 mM; ΔpH = −0.6; mM s⁻¹; ADP_i = 0.05 mM; mM s⁻¹; g_H = 0.01 mM s⁻¹ V⁻¹, [Ca²⁺]_i = 0.1 μM and AcCoA = 1.0 mM. The values of F₁F₀-ATPase concentration, ρ^F1, differ between curves, being 1.216 mM for curve a and 0.06 mM for curve b. (C) Changes in the relationship between ΔΨ_m and the respiratory rate obtained upon malonate titration at different phosphorylation potentials (different ratios of creatine to creatine phosphate) in a preparation of heart mitochondria. Redrawn from Borutaite et al. (1995).