Inflammation in the rat paw due to urate crystals. Involvement of the kinin system.

Monosodium urate and uric acid crystals induced kinin formation in Wistar rat plasma. They were inactive in the Brown Norway rat plasma which did not contain high molecular weight kininogen and had a low level in prekallikrein. Crystal-induced inflammation in the Brown Norway rat paw developed later and reached only 70% of the values observed in Wistar rats. Captopril, a kininase inhibitor, enhanced the oedema induced in the Wistar rat but did not affect the oedema in the Brown Norway rat. The leucocyte accumulation in the peritoneal cavity after uric acid injection was similar in both strains. The kinin system appeared to be involved in the inflammatory process induced in the rat by urate and uric acid crystals, as it is involved in carrageenan oedema.