Altered channel gating mechanism for CFTR inhibition by a high-affinity thiazolidinone blocker

To understand the biochemical events that control the generation of superoxide, the effect of inhibiting the respiratory complexes III and IV (C-III and C-IV) and alternative oxidase (AOX) on the rate of superoxide production was analyzed in mitochondria from maize seedlings. To increase superoxide production, it was required to inhibit C-III or C-IV by at least 30% or 50%, respectively. Below this inhibition threshold, AOX exerted the highest degree of control on superoxide production, whereas above it, the highest degree of control was exerted by C-IV. The contribution of C-III to control superoxide production became significant when AOX activity was modulated.