Metabolic changes in rabbit articular cartilage due to inflammation.

The effect of inflammation on the articular cartilage of rabbit knee joints were studied. The inflammation was induced by intraarticular injections of corton oil or rabbit peritoneal leukocyte lysates. An increase in the activities of various lysosomal enzymes was observed in the synovial fluid as well as in the cartilage of the inflamed joints. Loss of proteoglycans, increased rate of degradation of collagen and proteoglycans, and increased rate of their synthesis were evident in the treated cartilage. The rate of uptake of 3H-thymidine was also increased. A significant change was observed in the type of collagen synthesized by these explants in vitro. In addition to synthesizing their characteristics Type II collagen, the cartilage explants from the treated joints synthesized Type I collagen.