Urinary protein/peptide adducts as markers of reactive naphthalene (NA) metabolite formation in male mice

NA, an abundant PAH generated during combustion, has been shown to produce dose dependent cytotoxicity in murine airways and in rat and murine nasal epithelium. The relevance of findings in these animal models to human health is not clear, in part due to a high background of human lung diseases. Previous work has shown metabolism of NA in target tissues of rodents to reactive metabolites that covalently bind to such proteins as redox, extracellular, and cytoskeletal (Chem Res.Tox 18: 802, 2005). The current work focuses on monitoring urinary protein/peptide adducts as markers of key processes associated with NA toxicity. 24‐hour urine collected from male mice following ip administration of 14 C‐NA revealed specific activities of covalently adducted proteins that exceed those observed in lung. On SDS PAGE gels, these adducted proteins varied in size from 5–70 kDa. Much of the adducted protein in male mouse urine was approximately 12 kDa and is consistent with the formation of adducts with major urinary protein (MUP). Female mice, lacking MUPs, have significantly less protein which was adducted at lower specific activity in the urine. Resolution of urinary proteins by 2D electrophoresis and their subsequent identification by mass spectrometry is ongoing. We conclude that adducted proteins eliminated in the urine may be excellent markers of processes critical to target tissue toxicity. Supported by NIEHS 04311 and 04699.