Figure 4.

Changes in mitochondrial variables in response to the opening of a single IP₃R channel at the single mitochondrion level. A single IP₃R residing in the ER membrane is allowed to open for 100 ms starting at 100 s, and the maximum changes in different mitochondrial variables are recorded. The resting value (dotted lines) and the maximum value after the channel opens (solid lines) of [Ca²⁺]_M (A), Δψ (B), [NADH]_M (C), [ATP]_M, and (D) in WT (black lines), MICU1 KO (red lines), and MICU2 KO cells (blue lines). Parameters used in the simulations are the same as given in the text. The value of V_NaCa,max given by the model is 1.112, 1838.6, and 35.9675 μM/s.