Effect of Compound 48/80 on Toxicity of Histamine and of Serotonin in Mice.

(1) Compound 48/80 appears to have an additive effect on toxicity of histamine and a synergistic effect on toxicity of serotonin in the mouse. (2) Heparin interferes with this compound 48/80 effect on lethal intoxication with histamine or serotonin by direct interaction with compound 48/80 but does not appear to alter individual toxicities of respective amines. (3) It is suggested that degranulation of mast cells in response to compound 48/80 is a protective function of connective tissue in which the releaser drug is sequestered by heparin of the mast cell. The associated release of amines is thought to be a manifestation of this interaction between mast cells and compound 48/80 and only indirectly related (if at all) to lethal effects of this drug.