Dosimetry of N6-FormyllysineAdducts Following [13C2H2]-FormaldehydeExposures in Rats.

With formaldehyde as the major sourceof endogenous N6-formyllysine proteinadducts, we quantified endogenousand exogenous N6-formyllysine in the nasalepithelium of rats exposed by inhalation to 0.7, 2, 5.8, and 9.1 ppm[13C2H2]-formaldehyde using liquidchromatography-coupled tandem mass spectrometry. Exogenous N6-formyllysine was detected in the nasal epithelium,with concentration-dependent formation in total as well as fractionated(cytoplasmic, membrane, nuclear) proteins, but was not detected inthe lung, liver, or bone marrow. Endogenous adducts dominated at allexposure conditions, with a 6 h 9.1 ppm formaldehyde exposure resultingin one-third of the total load of N6-formyllysinebeing derived from exogenous sources. The results parallel previousstudies of formaldehyde-induced DNA adducts. [ABSTRACT FROM AUTHOR]