Acetaldehyde (CH3CHO) production in rodent lung after exposure to metal-rich particles

Epidemiological reports demonstrate an association between increased human morbidity and mortality with exposure to air pollution particulate matter ( PM). Metal-catalyzed oxidative stress has been postulated to contribute to lung injury in response to PM exposure. We studied the effects of residual oil fly ash (ROFA), a component of ambient air PM, on the formation of lung carbonyls that are indicators of lipid peroxidation. Rats were instilled i ntratracheally with ROFA (62.5-1000 mu g) and underwent lung lavage. Lavage fluid carbonyls were derivatized with 2,4-dinitrophenylhydrazine, and meas ured by high performance liquid chromatography with UV detection. Dose-depe ndent increases in a peak that eluted with the same retention time as the a cetaldehyde (CH3CHO) derivative was observed in rats treated with ROFA 15 m in after instillation (up to 25-fold greater than saline treated controls). The identification of CH3CHO was confirmed using gas chromatography-mass s pectroscopy. ROFA-induced increases in other lavage fluid carbonyls were no t seen, Increased CH3CHO in lavage fluid was observed as late as 8 h later. No increase in CH3CHO was observed in plasma from ROFA-treated rats. An in creased formation of CH3CHO was observed in a human airway epithelial cell line incubated with ROFA suggesting a pulmonary source of CH3CHO production . Instillation of solutions of metals (iron, vanadium, nickel) contained in ROFA, or instillation of another ROFA-type particle containing primarily i ron, also induced a specific increase in CH3CHO, These data support the hyp othesis that metals were involved in the increased CH3CHO formation. Thus m etals on PM may mediate lung responses through induction of lipid peroxidat ion and carbonyl formation. (C) 1999 Elsevier Science Inc.