[Changes in the pepsin activity of the gastric mucosa of rats in the early stages of carcinogenesis].

The paper discusses changes occurring in the enzymatic activity of pepsin in rat's gastric mucosa at early stages of carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine treatment with drinking water. All doses (5, 15, 45, 75 and 150 mg/l) proved to be effective and inhibited pepsinogen biosynthesis considerably. Particularly sharp drops in the enzyme activity were observed with the concentrations of 45, 75 and 150 mg/l. The effect was reversible at early stages, particularly, at low concentrations of the agent. It is suggested that the critical point reached by pepsinogen synthesis in gastric mucosa carcinogenesis, which is manifested by the enzyme synthesis resumption on treatment being suspended, may be regarded as the check point in the course of neoplastic development.