Nitric oxide mediates oxidant tissue injury caused by paraquat and xanthine oxidase.

In both paraquat and X/XO models of lung injury, the injury, previously attributed to the generation of reactive oxygen species, was related to the induction of NO. synthesis, and was totally preventable by inhibition of this synthesis. The results support the view that the NO. radical itself is an essential intermediary in the pathogenesis of at least some forms of oxidant tissue damage. Another form of oxidant injury, caused by prolonged perfusion of the lung ex vivo, is not mediated by NO. however.