CIGARETTE SMOKE-INDUCED DNA ADDUCTS IN THE RESPIRATORY AND NONRESPIRATORY TISSUES OF RATS

Formation of DNA adducts is regarded as an essential initial step in the process of chemical carcinogenesis. To determine how chronic exposure to cigarette smoke affects the distribution of DNA adducts in selected respiratory and nonrespiratory tissues, we exposed male Sprague-Dawley rats daily to fresh mainstream smoke from the University of Kentucky reference cigarettes (2R1) in a nose-only exposure system for 32 weeks. Blood carboxyhemoglobin, total particulate matter (TPM) intake, and pulmonary aryl hydrocarbon hydroxylase values indicated effective exposure of animals to cigarette smoke. DNA was extracted from three respiratory (larynx, trachea, and lung) and three non-respiratory (liver, heart, and bladder) tissues and analyzed for DNA adducts by the P-32-postlabeling assay under conditions capable of detecting low levels of diverse aromatic/hydrophobic adducts. Data showed that the total DNA adducts in the lung, heart, trachea, and larynx were increased by 10- to 20-fold in the smoke-exposed group. Five-fold increase was observed in the bladder tissue, but differences were not present in the liver DNA of control and smoke-exposed groups. These data suggest selective formation of DNA adducts in the tissues.