Effect of oxygen concentration on pulmonary fibrosis caused by peplomycin in mice.

The pulmonary fibrosis caused by peplomycin (PEP) was studied in terms of oxygen toxicity using ICR mice. When 16 micrograms of PEP was administered intratracheally in mice after exposure to the air containing 75% O2 for 10 days, the pulmonary fibrosis was completely suppressed, while when mice were exposed to 75% O2 after the administration of PEP, the fibrosis was much severe than that of mice raised in atmospheric air. In 50% O2, similar oxygen effect was also observed, but it was weaker than that in 75% O2. In 90% O2, the oxygen toxicity was observed in mice without administration of PEP. When mice were exposed to 75% O2, the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, which are relevant to the detoxication of active oxygen species, were not increased in the lung, but the levels of reducing agents such as glutathione and ascorbic acid, and high molecular substances having 1O2-scavenging activity were enhanced. The results suggest that these materials have some roles to decrease the pulmonary fibrosis caused by PEP.