Fig. 7. Mitochondrial ROS are required for pore opening. (A) Treatment of cells with an array of antioxidants (1mM ascorbic acid, 250 units/ml catalase, 1mM Trolox and 500 µM of the spin trap TEMPO) reduced the incidence of mitochondrial depolarisations, reducing the integrated activity from a control of 10.0±5.6 (n=53 cells) to 6.4±1.9 (n=57) (P<0.001, Mann-Whitney U test). (B) The antioxidants also significantly increased the time to global mitochondrial depolarisation (P<0.0001, Mann-Whitney U test).