Effect of N-methyl-N'-nitro-N-nitrosoguanidine on the gastric mucosal barrier in rats.

The gastric mucosal barrier to hydrogen ion (H+) after the administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on the rat stomach was studied. Increased H+ back-diffusion was observed 3 hr after oral doses of 1 mg of MNNG over a 3-day period. MNNG in concentrations of 250 microgram/ml, 167 microgram/ml, 86 microgram/ml, and 50 microgram/ml in the presence of acid caused increased H+ back-diffusion across the gastric mucosa within 1 hr. Gastric mucosal barrier disruption by MNNG may play a pathogenic role in gastric carcinogenesis.