The effect of H1 and H2 receptor blockers on immunological and nonspecific histamine release from isolated target cells.

The investigations were carried out on isolated peritoneal rat mast cells and human basophils. Cell histamine release was induced by a specific antigen, anti-IgE and by compound 48/80. Mepyramine and Diphenhydramine were used as H1 receptor blockers and Cimetidine as H2 receptor blocker. It was shown that effect of H1 and H2 receptor blockers on histamine release depends on concentration of drugs used in experiments, on the presence of exogenous histamine in the medium, on the kind of histamine liberators and also on the type of investigated target cells. The results obtained seem to indicate the presence of H2 receptors not only on basophils but also on mast cells.