Fig. 2.

The effect of auranofin on the apparent kinetics of H₂O₂ metabolism by rat skeletal muscle mitochondria. (A) Auranofin (2 µM) increases $V_{app}^P$ across several substrate conditions. Data are mean±SEM (n=4–5), ^⁎ significant increase due to auranofin (p<0.05). (B) The auranofin dependent increase in H₂O₂ efflux is strongly proportional to the apparent rate of H₂O₂ efflux in control mitochondria, consistent with a [H₂O₂]_matrix dependent consumer. Data mean±SEM (n=4–5) with auranofin-induced increase calculated as the difference in H₂O₂ efflux between the same mitochondria in the presence or absence of 2 µM auranofin to inhibit thioredoxin dependent peroxidase capacity. (C) The rate of extramitochondrial H₂O₂ disappearance (V ^Cmax_app) is substrate dependent and inhibited by auranofin (2 µM) in all cases. Data are mean±SEM (n=3–5), ^⁎ significant decrease due to auranofin (p <0.05). BLD=below limit of detection (i.e. not different from zero). (D) Comparison between $V_{app}^P$ and $V_{app}^{Cmax}$ in muscle mitochondria respiring on different substrates. Control (black) or auranofin (grey) values are taken from Fig. 2A and C with each substrate condition indicated by a different symbol. Linear regressions are shown to illustrate the relationship between apparent rates of production and consumption.