[A study on formation of N-(nitrosomethyl) urea in experimental pig stomach gavaged with fish sauce].
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 micromol/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.


CONCLUSIONS
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.
Xin
H
H
Beijing Institut for Cancer and School of Oncology, Beijing Medical University, Beijing 100034.
Deng
D
D
Wang
R
R
Gu
L
L
D000818:Animals; D005396:Fish Products; D005750:Gastric Juice / Q000737:chemistry*; D005753:Gastric Mucosa / Q000378:metabolism; D008297:Male; D008770:Methylnitrosourea / Q000032:analysis / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D013552:Swine; D013556:Swine, Miniature
D009573:Nitrites; D008770:Methylnitrosourea