Effect of pre-exposure to benzo(a)pyrene, nitropyrene, and SO2 on metabolism of benzo(a)pyrene and nitropyrene in lungs and nasal tissue of rats

Pre-exposure of rats for 4 wk to diesel exhaust particles resulted in a twofold increase in the metabolism of 1-nitropyrene by rat respiratory tract tissue. The experiments reported here were designed to investigate which individual constituents of diesel exhaust were responsible for the observed enzyme induction. Rats were exposed nose-only for 2 h or for 4 wk (2 h/day, 5 day/wk) to either air only, benzo(a)pyrene (BaP), 1-nitropyrene (NP), or SO2. Nasal tissue and lungs were removed from the rats and the metabolism of 14C-BaP and of 14C-NP was investigated. After a 2-h exposure to BaP, nasal tissue metabolism of 14C-BaP was increased twofold over controls. After a 4-wk exposure to NP, nasal tissue metabolism of 14C-NP was decreased to 30% of controls. Exposure to SO2 for 2 wk increased 14C-NP metabolism and decreased 14C-BaP metabolism in the lungs. 2 references, 2 figures