An analysis of mutagens in the contents of the biliary tract in pancreaticobiliary maljunction.

A reflux of pancreatic juice into the biliary tract due to pancreaticobiliary malfunction has been considered to be an important factor in the development of biliary tract carcinogenesis. It is known that the contents of the biliary tract contain not only activated pancreatic enzymes but also certain mutagens. The purpose of this study was thus to isolate and identify such mutagenic substances. A 1:1 mixture of the control bile and pancreatic juice was mixed with bovine enterokinase (10 mg/ml), and the mixture was incubated at 37 degrees C for 12 h. The mixture was demonstrated to be reproducibly mutagenic by the Ames test. The mutagenic substances in these mixtures, which were separated using organic analysis, were found to be included in the water-soluble fraction and to contain amino acids. Mutagenic substances are thought to have a molecular weight of 1,500-3,500 and to be a complex of low-molecular-weight, stable, mutagenic substances including amino acids and peptides.