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APPLICATION OF THE EPR SPIN-TRAPPING TECHNIQUE TO THE DETECTION OF RADICALS PRODUCED IN VIVO DURING INHALATION EXPOSURE OF RATS TO OZONE
Citation:
Kennedy, C., G. Hatch, R. Slade, AND R. Mason. APPLICATION OF THE EPR SPIN-TRAPPING TECHNIQUE TO THE DETECTION OF RADICALS PRODUCED IN VIVO DURING INHALATION EXPOSURE OF RATS TO OZONE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/299 (NTIS PB92227412).
Description:
Ozone is known to induce lipid peroxidation of lung tissue, although no direct evidence of free radical formation has been reported. e have use the electron paramagnetic resonance (EPR) spin-trapping technique to search for free radicals produced in vivo by ozone exposure. he spin trap a-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN) was administered i.p. to male Sprague-Dawley rats. he rats were then exposed for 2 hrs to either 0, 0.5, 1.0 or 2.0 ppm ozone with 8% C02 to increase their respiratory rate. -line 4-POBN/radical spin adduct signal aN=15.02 G and aHb=3.27 G) was detected by EPR spectroscopy in lipid extracts from lungs of rats treated with 4-POBN and then exposed to ozone. nly a very weak signal was observed in the corresponding solution from rats exposed to 0 ppm ozone (air with C02 only). he concentration of the radical adduct increased as a function of ozone concentration. fter administration of 4-POBN, rats were exposed or either 0.5, 1.0, 2.0 or 4.0 hrs to either 0 or 2.0 ppm ozone (with C02). he radical adduct concentration of the ozone-exposed groups at exposre times of 2.0 and 4.0 hrs was significantly different from that of the corresponding air control groups. orrelation was observed between the radical adduct concentration and the lung weight/body weight ratio. hese results demonstrate that ozone induces the production of free radicals in rat lungs during inhalation exposure and that radical production may be involved in the induction of lung edema by ozone. his is the first direct evidence for ozone-induced free radical production in vivo.