Comparison of pulmonary DNA adduct levels, measured by 32P-postlabelling and aryl hydrocarbon hydroxylase activity in lung parenchyma of smokers and ex-smokers

In order to compare pulmonary DNA adducts and aryl hydrocarbon hydroxylase (AHH) activity, we have measured these two parameters in non-neoplastlc surgical lung parenchymal samples from four ex-smokers and 19 smokers, out of 20 patients operated for lung cancer, and three for non-malignant lung diseases. DNA adducts were determined by scintillation counting after 32P-postlabelling analysis. The microsomal fractions of the same lung specimen were assayed for AHH activity by a fluorometric method. Autoradiograms of DNA adducts found in lungs of smokers revealed two distinct diagonal radioactive zones that were absent in ex-smokers. The smokers had significantly higher levels (1.68–13.4 DNA adducts/108 nucleotides; mean ± SD 5.38 ± 3.19) than ex-smokers (0.23–2.21; 1.09 ± 0.84). AHH activity in smokers ranged from 0.01 to 0.69 pmol/min/mg. This activity was significantly (P < 0.05) higher in smokers (0.26 ± 0.26) who had smoked until 1 week before surgery than in those who had stopped smoking for