Abstract: OBJECTIVE:To study the mutagenicity of cigarette smoke condensates(CSC) in the TK gene mutation assay and to compare the mutagenicity of TK gene in cigarette samples with different tar release. METHODS:3 commercial cigarettes of different tar releases,5 mg(1^#),8 mg(2^#) and 11 mg(3^#),were tested. The mouse lymphoma cell line L5178Y tk^+/-3.7.2C was treated with 20 μg/mL,40 μg/mL,60 μg/mL,80 μg/mL,100 μg/mL and 150 μg/mL CSC from the 3 cigarette samples. 15 μL/mL DMSO treatment was used as the solvent control,and 3 μg/mL cyclophosphamide treatment was used as the positive control. The test protocol includeds the 4-h treatment,2-day expression and 12-day cloning phases. Then the mutation frequency of trifluorothymidine resistance (TMF) of each dose group was calculated. Finally,the mutagenic potency of different cigarette samples was compared. RESULTS:At the dose of 150 μg/mL of 1^#,100 μg/mL of 2^# and 3^#,the TMF were more than 3 times higher than that in the solvent control group. In addition,the TMF increased with increase of the CSC doses. The mutagenic potency of the CSCs for 3 cigarette samples were 0.37,0.36 and 0.38,respectively. CONCLUSION:All CSCs induced dose-dependent increases of mutagenicity in the mouse lymphoma assay. Comparing the mutagenicity of the 3 cigarette samples,there was no significant correlation between TK gene mutagenic potency and tar release in cigarette smoke.

Key words: cigarette smoke condensate, tar, TK gene mutation test, mutagenic potency