CRYSTAL-INDUCED INFLAMMATION IN THE RAT SUBCUTANEOUS AIR-POUCH

1. Monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystals initiated acute inflammatory reactions characterized by increased plasma extravasation and polymorphonuclear leukocyte (PMNL) accumulation in the rat subcutaneous air-pouch. 2. Pretreatment of rats with colchicine (1 mg/kg-1, s.c.) inhibited PMNL accumulation induced by either crystal type but had a greater inhibitory effect on MSU-induced plasma extravasation compared with that induced by CPPD crystals. 3. Colchicine (1 mg/kg-1, s.c.) did not reduce histamine-induced plasma extravasation in the air-pouch. 4. The lipoxygenase product of arachidonic acid metabolism, leukotriene B4 (LTB4), was detected in MSU-induced exudates but not in CPPD-induced exudates. 5. Pretreatment of rats with colchicine (1 mg/kg-1, s.c.) inhibited LTB4 production in MSU-induced exudates.