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

Calcium chloride (CaCl2) inhibits stimulation of replicative DNA synthesis (RDS) induced in the pyloric mucosa of male Fischer 344 rats by sodium chloride (NaCl), which is a tumor promoter in the glandular stomach. Administration of 1 ml of 3.3 M NaCl by gastric intubation induced a maximal 15-fold increase in RDS in the pyloric mucosa by 17 h; this had returned to the control level by 48 h. Administration of 1 ml of 20-400 mM CaCl2 1 h before administration of NaCl resulted in a 60-100% inhibition of the increase in RDS within 4-48 h; the inhibition was dose-dependent. The 400 mM level of CaCl2 also decreased the histological damage to surface epithelial cells induced by NaCl. These results suggest that calcium ion acts as an anti-tumor promoter in stomach carcinogenesis.