The pH sensitivity of H2O2 metabolism in skeletal muscle mitochondria

Mitochondria have the capacity to produce and consume H 2 O 2 . We examined H 2 O 2 metabolism in isolated rat skeletal muscle mitochondria and found that the substrate‐dependent capacity to consume extramitochondrial H 2 O 2 was markedly higher than the observed rate of H 2 O 2 efflux from mitochondria under the same conditions. The substrate‐dependent capacity to consume H 2 O 2 was sensitive to the pH of the medium and we propose that pH related differences in H 2 O 2 consumption pathways may explain inconsistencies we observed between H 2 O 2 efflux rate and the reduction state of the matrix NADH pool.