鱼露灌胃后猪胃内N-亚硝基甲基脲的合成

A Study on Formation of N (nitrosomethyl) urea in Experimental Pig Stomach Gavaged with Fish Sauce

目的 研究胃癌高发区福建省长乐县居民经常食用的鱼露在实验猪胃内合成强致癌性亚硝酰胺类物质Ｎ亚硝基甲基脲（ＮＭＵ） 的情况。方法 对小型实验香猪胃造瘘，经瘘管灌注鱼露和ＮａＮＯ２，３０ 分钟后抽取胃液，经纯化浓缩，用高效液相色谱光水解热裂解器热能分析仪联机装置，检测胃液样品中的ＮＭＵ。结果 在ｐＨ 值１ ～２ 条件下，检测到猪胃内合成的ＮＭＵ；ＮＭＵ 合成量与添加的亚硝酸盐量有剂量依赖关系：当ＮａＮＯ２ 灌胃３ ．４８ 和０ ．８７ ｍ ｍｏｌ 时，胃液中ＮＭＵ 浓度分别为２５ ．４ 和７－９７ μｍｏｌ／Ｌ；而当ＮａＮＯ２ 为０ ．２２ ｍｍｏｌ 时，没有检测到ＮＭＵ。结论 在一定的胃内酸性条件及亚硝酸盐存在的情况下，接受鱼露灌胃的实验猪胃内有ＮＭＵ 的合成。因此推测胃内亚硝酸盐水平较高且经常食用鱼露者，胃内极可能有ＮＭＵ 等亚硝酰胺的内源性合成。

Objective To study formation of N (nitrosomethyl) urea (NMU), which is categorized as N nitrosamides —— a sort of strong chemical carcinogen, by perfusion with fish sauce via pig stomach fistula, which is used daily as cooking flavor by local residents in Changle County, Fujian Province, a highly prevalent area for gastric cancer. Methods Fistulization was performed in fasting experimental pigs' stomach, and their gastric juice was suctioned 30 minutes after perfusion with fish sauce and sodium nitrite via fistula. Gastric juice specimen was purified and concentrated and determined for NMU with high performance liquid chromatography photolysis pyrolysis thermal energy analyzer. Results NMU was detected in the pig stomach at pH 1 2, where NMU formed. Formation of NMU depended on the amount of nitrite added in a dose dependent relationship. Level of NMU in gastric juice reached 25.4 and 7.97 μmol/L, respectively, when 3.48 and 0.87 mmol of sodium nitrite were fed into the stomach. No NMU could be detected, as 0.22 mmol of sodium nitrite fed. Conclusion Under the condition of pH 1 2 and presence of sodium nitrite, NMU was synthesized in the stomachs of experimental pigs fed with fish sauce via gastric fistula. It is postulated that N nitrosamides, such as NMU could be formed endogenously in the stomachs of local residents who consume fish sauce often and have a higher exposure to nitrite in their stomachs.