Figure 4.

Endogenous (¹²C) and exogenous (¹³C) N²-Et-dG in nasal tissues including respiratory epithelium (A) and olfactory epithelium (B). Data were shown in means and standard deviations. Endogenous N²-Et-dG and exogenous [¹³C₂]-N²-Et-dG from nasal tissues are analyzed by LC-MS/MS. Olfactory epithelium under exposure to 1 ppm and 10 ppm [¹³C₂]-VAM were analyzed for 120 µg DNA with n = 3 or 5 replicates. Other tissues are analyzed for 10 µg with n = 7 replicates. Nondetected groups were annotated with “N.D.”