Increased fixation of sulfur-35 by cartilage in vitro following depletion of the matrix by intravenous papain.

The uptake in vitro of sulfur-35 by costal cartilage obtained from nine rabbits 11 days after an intravenous injection of crude papain solution was compared with that in costal cartilage from eight normal untreated rabbits. An increased fixation of the isotope was found in treated animals compared with controls. The depletion of cartilage matrix by papain provided an experimental situation to test the hypothesis that the depletion of matrix which occurs in osteoarthritic cartilage can stimulate increased synthesis of chondroitin sulfate. The results give further support to the view that the primary lesion in osteoarthritis occurs in the matrix rather than in the chondrocyte of articular cartilage.