Nox2-containing NADPH oxidase and xanthine oxidase are sources of superoxide in mouse trachea.

1. Superoxide anion plays an important role in host defence against invading pathogens and in the inflammation that arises in lungs. The aim of the present study was to elucidate whether the two key candidate superoxide-producing enzymes in mammalian cells, namely Nox2-containing NADPH oxidase and xanthine oxidase, are responsible for superoxide production in mouse trachea. 2. Superoxide production by isolated trachea, as measured by L-012-dependent chemiluminescence, was markedly reduced by superoxide dismutase (300 U/mL) and the xanthine oxidase inhibitor allopurinol (100 micromol/L). Tracheas from Nox2(-/-) mice had significantly lower levels (~60%) of superoxide than control mice. 3. These novel findings suggest that superoxide production by mouse trachea is attributed to both Nox2-containing NADPH oxidase and xanthine oxidase.