Figure 7.

Comparison of succinate-driven H₂O₂ production by RET in intact fully polarized mitochondria with succinate-driven H₂O₂ production by complex II after permeabilization with alamethicin. A, demonstration that stigmatellin (Stigm, 1 μm) dissipates ΔΨ required for H₂O₂ production by RET in intact mitochondria (Mito) energized with succinate (Succ, 0.5 mm). P_i 2.5 mm. B, as expected, stigmatellin (1 μm) inhibited succinate-induced H₂O₂ production by RET. The [succinate] is indicated at the end of each trace. Subsequent addition of alamethicin (Ala) robustly stimulated H₂O₂ production in the presence of endogenous or low exogenous [succinate], but it had no effect at 5 mm [succinate] (purple trace). Malonate (Malon, 1 mm) suppressed the increase H₂O₂ production induced by alamethicin. P_i 2.5 mm. As in other figures, additions to all traces are indicated by black arrows; additions to one trace only are indicated by the arrows of the same color as the trace. C, summary data (median ± 95% confidence intervals, *, p < 0.05) of the effect of [succinate] on H₂O₂ production in stigmatellin-inhibited mitochondria after alamethicin permeabilization and inhibition by malonate.