IN-VIVO EVIDENCE OF FREE-RADICAL FORMATION IN THE RAT LUNG AFTER EXPOSURE TO AN EMISSION SOURCE AIR-POLLUTION PARTICLE

Exposure to air pollution particles can be associated with increased h uman morbidity and mortality. The mechanism(s) of lung injury remains unknown. We tested the hypothesis that lung exposure to oil fly ash (a n emission source air; pollution particle) causes in vivo free radical production. Electron spin resonance (ESR) in conjunction with the spi n trap alpha-(4-pyridyl 1-oxide)-N-tert-butylnitrone (4-POBN) was used to detect radical adducts. Rats were instilled with 500 mu g of eithe r oil fly ash or saline, Twenty-four hours later, ESR spectroscopy of the chloroform extract from lungs of animals exposed to the oil fly as h gave a spectrum consistent with a carbon-centered radical adduct (hy perfine coupling constants a(N) = 15.0 G and a(beta)(H) = 2.5 G), whil e those spectra from lungs instilled with saline revealed a much weake r signal. This signal was reproduced by instilling animals with the so luble fraction of the ail fly ash, which contains soluble metal compou nds. The same signal was observed after instillation of either a mixtu re of vanadium, nickel, and iron sulfates or VOSO4 alone, We conclude that, after instillation of an air pollution par-tide in the rat, ESR analysis of lung tissue demonstrates in vivo free radical production, This generation of free radicals appears to be associated with soluble metals in the oil fly ash.