Fig. 8. _m depolarization frequency increased with [TMRE] or intensity of excitation light and was inhibited by antioxidants or cyclosporin A. (A) The frequency of _m depolarizations plotted against [TMRE] (10-150 nM) with (shaded bars) and without (white bars) the attenuation of excitation light by a neutral density filter (^*P<0.05, ^**P<0.01). (B) The mPTP inhibitor cyclosporin A (CsA, 2 µM) or a combination of antioxidants [ascorbic acid (1 mM), catalase (250 units/ml), Trolox (1 mM) and TEMPO (500 µM)] each decreased the number of _m depolarizations observed at 150 nM TMRE (^**P<0.01). Cells were co-loaded with TMRE and Fluo-4 (10 µM) and fluorescent images acquired at 1 Hz.