Figure 2.

Dynamical behaviors of the single mitochondrion model. (A) Steady-state matrix superoxide concentration ([O⁻₂]_M, black line) and IMAC open probability (P_IMAC, gray line) versus k_shunt. Dashed segments are unstable steady states. (B) Steady-state matrix H₂O₂ concentration ([H₂O₂]_M, gray line) and MPTP open probability (P_MPTP, gray line) versus k_shunt. Dashed segments are unstable steady states. Loss of stability of the steady state leads to oscillations (OSC zones in A and B) and bistability (BS zones in A and B). Dashed arrow indicates that as k_shunt increases continuously, a sudden jump occurs in H₂O₂ concentration. (C) The intermembrane superoxide concentration ([O⁻₂]_I, dashed line) and intermembrane H₂O₂ concentration ([H₂O₂]_I, solid line) versus time for k_shunt = 0.08 mM/s, which is in the oscillatory regime. (D) The intermembrane H₂O₂ concentration in the bistable regime showing two stable steady states (solid and dashed lines) resulted from two initial conditions at k_shunt = 0.2 mM/s. (E) Steady-state matrix H₂O₂ concentration ([H₂O₂]_M) versus k_shunt and RED_Total. The thick segments are the stable steady states. The thin segments are unstable steady states. “OSC” and “BS” mark the oscillatory and bistable regions, respectively.