We measured production of reactive oxygen species by intact mitochondria from rat skeletal
muscle, heart, and liver under various experimental conditions. By using different substrates
and inhibitors, we determined the sites of production (which complexes in the electron
transport chain produced superoxide). By measuring hydrogen peroxide production in the
absence and presence of exogenous superoxide dismutase, we established the topology of
superoxide production (on which side of the mitochondrial inner membrane superoxide was …