Effect of histamine H1- and H2-receptor antagonists, steroidal and non-steroidal anti-inflammatory agents on carrageenin-induced inflammation of the guinea-pig ear.

The role of histamine H1- and H2-receptors in mediating the vascular events associated with carrageenin-induced inflammation has been investigated in the guinea-pig ear. Increased vascular permeability, oedema formation and vasodilatation, a parameter known to be reduced by cimetidine in inflammatory responses where histamine is widely accepted as an important mediator, were quantitatively measured. Cimetidine and mepyramine, alone and in combination, failed to modify the vascular changes produced by carrageenin; conventional doses of steroidal and non-steroidal anti-inflammatory agents were also found to be ineffective. Furthermore, combinations of cimetidine, mepyramine and indomethacin had only minor effects on the inflammation. These findings suggest that histamine and cyclo-oxygenase derived metabolites of arachidonic acid do not play a significant role in carrageenin-induced inflammation in the guinea-pig.