Fig. 5.

Increased sensitivity of cortical mitochondria to oxidative stress in PINK1^−/− mice. (A) The reduction of state 3 respiration by complex I after 15 min of exposure to 100 μM H₂O₂ was more dramatic in mitochondria isolated from the PINK1^−/− cortex at 3–4 months than from the control (*, P < 0.05, n = 5). Data are expressed as a percentage of the activity of the same sample measured previously in standard conditions. (B) Effect of 15 min of exposure to 500 μM H₂O₂ on complex II respiratory capacity of cortical mitochondrial preparation at 3–4 months. (*, P < 0.05, n = 9). Data are expressed as a percentage of the activity of the same sample measured previously in standard conditions. (C) Effect of exposure to a mild heat shock (10 min at 43°C before assay) on complex II respiratory capacity of cortical mitochondria preparation at 3–4 months. Data are normalized to WT activity under standard conditions (*, P < 0.05, n = 6). (D) Measure of the transmembrane potential of isolated mitochondria at 3–4 months after 15 min of exposure to 100 μM H₂O₂ by the JC-1 assay. (E) Mitochondria swelling assay. Data are fitted as the sum of exponentials. τ₁ is given as the time constant of the first and main exponential. No difference between genotype was seen under basal conditions or after 15 min of exposure to 200 μM H₂O₂ (N.S.: not significant, n = 4).