Effects of the H2-antagonists famotidine and nizatidine and the cytoprotectant misoprostol on human colonic and rat peritoneal mast cells

The H₂-antagonists famotidine and nizatidine produced a dose-dependent inhibition of histamine release from human colonic mucosal and muscle mast cells stimulated with anti-IgE. The IC₃₀ values were in the range 0.5–10 μM and the maximum inhibition approached 50%. The compounds showed similar efficacy against rat peritoneal mast cells but were more potent. The cytoprotectant misoprostol had a striking effect on the human colonic mast cells, producing more than 50% inhibition at concentrations of 0.1–1 nM, but was much less active against the rat cells.