Calcium chloride inhibits stimulation of replicative DNA synthesis by sodium chloride in the pyloric mucosa of rat stomach

Calcium chloride (C_aCl₂ inhibits stimulation of replicativeDNA synthesis (RDS) induced in the pyloric mucosa of male Fischer344 rats by sodium chloride (NaCl), which is a tumor promoterin the glandular stomach. Administration of 1 ml of 3.3 M NaClby gastric intubation induced a maximal 15-fold increase inRDS in the pyloric mucosa by 17 h; this had returned to thecontrol level by 48 h. Administration of 1 ml of 20–400mM CaCl₂ 1 h before administration of NaCl resulted in a 60–100%inhibition of the increase in RDS within 4–48 h; the inhibitionwas dose-dependent. The 400 mM level of CaCl₂ also decreasedthe histological damage to surface epithelial cells inducedby NaCl. These results suggest that calcium ion acts as an anti-tumorpromoter in stomach carcinogenesis.