DNA damage and repair in female C57BL/10 mice of different ages injected with the carcinogen benzo[a]pyrene-trans-7,8-diol.

Female C57BL/10 mice 2 and 14 months of age were killed 3, 6, 9, 12, 18 and 24 h after injection with 0.4 mg of benzo[a]pyrene-trans-7,8-dihydrodiol. The amount of carcinogen bound to DNA isolated from liver and kidney of each mouse was determined as benzo[a]pyrene-7,8,9,10-tetrol liberated upon acid hydrolysis of the DNA and measured by synchronous scanning fluorometry. Considerable variability was observed and a subset of animals in the middle-aged group failed to sustain appreciable damage upon injection of the carcinogen. Nevertheless, repair of DNA-bound carcinogen from both the liver and kidney of 2-month-old animals was clearly evident. In the subset of 14-month-old animals who sustained damage, evidence for removal of DNA-bound carcinogen was marginal.