Pharmacological modulation of 2-methyl-carbamate-PAF induced rat paw oedema

Intraplantar injections of 2-methyl-carbamate-PAF (2-MC) (0.125-16.0 micrograms/paw) into the rat paw were followed by a bell-shaped dose response curve for inflammatory oedema, with an ascending phase at 0.125-2.0 micrograms/paw, and a descending phase at 4.0-16.0 micrograms/paw. The inflammatory response to 2-MC was partially inhibited by pre-treatment with aspirin (200 mg kg-1), NDGA (100 mg kg-1), dexamethasone (0.1 mg kg-1), verapamil (50 mg kg-1) and by a specific PAF antagonist BN 52021 (5-10 mg kg-1). The cyclo-oxygenase inhibitors indomethacin (2 mg kg-1) and piroxicam (1.8 mg kg-1) as well as antihistamine meclizine (40 mg kg-1) and ranitidine (50 mg kg-1) failed to block the oedematogenic response to 2-MC. Our data suggest that 2-MC induced rat paw oedema is mediated by PAF-acether receptors and is partially dependent on arachidonate lipoxygenase pathway and extracellular Ca2+.