Inhibition by purine nucleotides of the release of reactive oxygen species from muscle mitochondria: Indication for a function of uncoupling proteins as superoxide anion transporters

► GDP and GTP decrease release of reactive oxygen species from muscle mitochondria. ► The release of superoxide anion rather than that of hydrogen peroxide is inhibited. ► GTP increases accumulation of reactive oxygen species within mitochondrial matrix. ► Uncoupling proteins may function as mitochondrial carriers of the superoxide anion.