(materials and methods)
Calcium pyrophosphate dihydrate (CPPD) crystals were prepared using radioisotope (Ca^<45>). Five mg of these crystal were injected into the rat air pouch (synovial space). Synovial fluid was aspirated and synovial tissues were removed from air pouch 0, 2, 12, 24, 48, 120, 168 hours after crystal injection. After centrifuging the synovial fluid and dissolving the synovial tissues of each group, CPPD crystal in supernates, sediments and dissolved solution of the synovial tissues were measured using liquid scintillation counter.
1. CPPD in the sediments were 3 4.6% of total amounts injected into rat air pouch at 2 hours after injection, 20.7% at 6 hours, 11.0% at 12 hours , 1.9% at 24 hours, 0.5% at 48 hours.
2. CPPD in the dissolved solution of the synovial tissues were 4.9% of total amounts injected into rat air pouch at 2 hours after injection, 65.6% at 6 hours, 47.0% at 12 hours , 28.7% at 24 hours, 30% at 48 hours.
3. Histological examination of the synovial tissue revealed that CPPD crystals were attached to the surface of synovium and did not taken into the synovial tissues at 6 hours. CPPD crystals and inflammatory cells were taken into the synovial tissues (inside the synovial membrane) at 24 hours.
(conclusion) Synovial tissues have some role to induce spontaneous remission for crystal induced inflammation.