Benzalkonium chloride inhibited the histamine release from rat peritoneal mast cells induced by bradykinin and GlcNAc oligomer-specific lectin Datura stramonium agglutinin, but heparin did not.

1. Benzalkonium chloride (BAC) inhibited the histamine release from rat peritoneal mast cells induced by synthetic cationic polymers (compound 48/80 and PEI6), bradykinin, des-Arg1-bradykinin and des-Arg9-bradykinin and Datura stramonium agglutinin (DSA). 2. The anionic polymers heparin, de-N-sulfated heparin, poly-aspartic acid and poly-glutamic acid dose dependently inhibited the histamine release induced by cationic polymers, suggesting counteraction between anions and cations. 3. Inhibition by heparin was diminished but that of BAC remained after removal of extracellular heparin and BAC. 4. Mast cell activation by bradykinin and DSA was not inhibited by anionic polymers, suggesting that both bradykinin and DSA recognize membrane sites as receptors.