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EVALUATION OF TOXICITY BY OIL FLY-ASHES IN RAT ALVEOLAR EPITHELIAL CELLS: ROLE OF FENTON DRIVEN OH-RADICAL GENERATION AND PARATICLE FRACTION
Citation:
Borm, P., T. Shi, U P. Kodavanti, AND R. Schins. EVALUATION OF TOXICITY BY OIL FLY-ASHES IN RAT ALVEOLAR EPITHELIAL CELLS: ROLE OF FENTON DRIVEN OH-RADICAL GENERATION AND PARATICLE FRACTION. Presented at Society of Toxicology, Nashville, TN, March 17-21, 2002.
Description:
Leachable transition metals are considered to be important mediators in the biological effects of ambient particulate matter (PM) and model particles such as oil-fly ashes (OFA). We determined metal driven Fenton activity in 10 OFA in the presence of hydrogen peroxide using electron spin resonance (EPR) and a suitable spin-trap (DMPO) and their ability to induce 8-hydroxydeguanosine (8-OH-dG) in nude DNA using immunodotblot. In addition, the toxicity of the OFA suspensions and supernatants was determined in a rat alveolar type II cell line using leaching of LDH (membrane damage) or conversion of MTT (mitochondrial function). Suspensions of OFA were consistently more toxic than their filtrates obtained by centrifugation and 0.1 um filtration. Correlations between both cytotoxicity assays were seen using OFA suspensions (r =0.862) but not for the filtrates. The DMPO-OH generation of filtrates in water did correlate well with the cytoxicity assessed by MTT conversion of the filtrate (r =0.820) and the formation of 8-OHdG (r=0.57). Together these findings suggest that the different fractions of OFA exert cytotoxicity through different mechanisms. This is supported by different effects of filtrate and suspensions on 8-OHdG formation and DNA unwinding. The watersoluble Fenton-active fraction seems to affect mitochondrial competence (MTT), while the membranolytic effects seem to be determined by the total suspensions.(This abstract does not reflect USEPA policy).