Citation:

Kennedy, C., G. Hatch, R. Slade, AND R. Mason. DETECTION OF RADICALS PRODUCED IN VIVO DURING INHALATION EXPOSURE TO OZONE: USE OF VARIOUS SPIN TRAPS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/D-91/111 (NTIS PB91196113), 1991.

Description:

Ozone is known to induce lipid peroxidation of lung tissue, although no direct evidence of free radical formation has been reported. e have used 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, 1.5 or 2.0 ppm ozone with 8% CO2 to increase their respiratory rate. -line 4-POBN/radical spin adduct signal (aN=15.02 G and a HB-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 CO2 only). he concentration of the radical adduct increased as a function of ozone concentration. fter administration of 4-POBN, rats were exposed for either 0.5, 1.0, 2.0 or 4.0 hrs to either 0 or 2.0 ppm ozone (with CO2). he radical adduct concentration of the ozone-exposed groups at exposure 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.

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