Role of lipid-derived free radical in bleomycin-induced lung injury in mice: availability for ESR spin trap method with organic phase extraction.

Bleomycin is well known as causative molecule for acute lung injury and interstitial pneumonia. The free radical production from bleomycin is thought to play an important role in the pathogenesis of acute lung injury and interstitial pneumonia. However, there was no direct evidence of free radical production in this model. Therefore, we examined in vivo radical production by mice treated with a bleomycin using electron spin resonance with the spin trap, alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone. Six hours after instillation of bleomycin, the lung exposed to bleomycin gave a lipid-derived free radical adduct, which would support evidence for in vitro lipid peroxidation resulting from bleomycin administration. In the treatment of deferoxamine, chelating agent for iron and other metals, to reduce the bleomycin induced free radical production, parallel to decrease the lipid-derived free radical production by deferoxamine, pathophysiological findings of lung injuries were improved by deferoxamine. In conclusion, this is a first paper of in vivo direct evidence of production of free radical from bleomycin-induced lung injury. It is suggested that this method may be used in many kinds of lung disease models, which have potentials of free radical production to cause lung damage.