Formation of N-trimethyl-N-nitrosourea in the gastric lumen of the fistulated pig.

The formation of N-trimethyl-N-nitrosourea (TMNU) in the stomach of full-sized gastric-fistulated pigs was determined. Nitrite was added to the stomach in amounts that have been reported to occur in the human stomach (25-375 mumol). The vehicle was an 'artificial meal' made up of synthetic gastric juice. The total amount of TMNU formed (not concentration) was estimated by determining the concentration and gastric volume using multiple additions of a nonabsorbable marker (polyethylene glycol). At an initial pH of 3, 23-1000 micrograms of TMNU were found after 10-25 min. The rate of loss of polyethylene glycol and TMNU from the stomach were the same, indicating that TMNU was not directly absorbed. These data suggest that formation of TMNU under conditions similar to those found in the human stomach is possible.