Effect of pH on mutagenicity of urine from smokers and nonsmokers

Cigarette smoking is a major risk factor for bladder cancer. Some chemicals from cigarette smoke e.g. aromatic amines, are metabolized in the liver and excreted in urine as either glucuronide or acetyl conjugates. These metabolites undergo pH mediated activation to reactive nitreneum ions that may lead to DNA adducts, initiating bladder tumorigenesis in some smokers. We hypothesize that changing the pH of smokers urine will impact the mutagenic outcome of these metabolites. Overnight samples were collected from smokers (n=11) and nonsmokers (n=11) and stored at -70°C. Each urine sample was adjusted to neutral (7.0), basic (8.2) and acidic (5.5) pH. Mutagenic activity was assessed with the Ames test utilizing the Salmonella Typhimurium strain YG1024 microsuspension assay. Urine from smokers was significantly mutagenic compared with nonsmokers (P<0.001). In both the groups, there was no difference between urine adjusted at different pH (P>0.05). We conclude that changing the pH of smokers urine might not affect their subsequent risk for bladder cancer.