[Mutagenicity of gastric and duodenal juice on gastric carcinogenesis in rats with duodenal reflux].

A mutagenicity of gastric and duodenal contents in regard to gastric carcinogenesis was estimated in animals with duodenogastric reflex. Male Wistar rats were subjected to one of following four types of operative procedures: 1) Reflux through the pylorus (DGR), b) DGR + truncal vagotomy (DGR + V), 2) Control group; a) sham operation treated with gastrotomy (SO), b) SO + truncal vagotomy (SO + V). No carcinogens were given to animals, and they were killed 50 weeks after surgery. No cancers were detected in any of 25 animals in the control group, but nine (41%) of 22 animals in the reflux group had gastric adenocarcinoma. The count of nitrate-reducing bacteria of gastric juice was increased in DGR + V and SO + V groups, and that of duodenal juice was increased in DGR and DGR + V groups. The mutagenicity according to umu test was detected in DGR and DGR + V in both gastric and duodenal juice, but no mutagenicity was observed in the control group. These results suggested that the gastric and duodenal juice in animals with duodenogastric reflux have potent mutagenic activity. The carcinogen is likely to be produced not only in the stomach but also in the duodenum, and its production may be associated with overgrowth of nitrate-reducing bacteria.