In vitro Histamine Release from Rat Mast Cells by Chemical and Physical Agents. ∗

Summary

Release of histamine from suspensions of rat peritoneal mast cells under various conditions has been measured directly by a microchemical technic. Compound 48/80 released histamine in a concentration as low as 2 × 10^-7M and was the most potent substance investigated. Several other substances released histamine; the effects of compound 1935L, protamine, n-octylamine and stilbamidine were evaluated at several concentrations and compared with those of 48/80. Stilbamidine was considerably less potent than the others. As expected, certain physical changes released histamine, and low temperatures prevented 48/80 histamine release. Qualitative variations in response of these mast cells to different releasers suggested that mechanisms of histamine release vary considerably among the chemical agents now being investigated.