The effect of synovial catabolin on cartilage synthetic activity.

The effect of porcine synovial catabolin on the incorporation of [3H]amino acids and [35S]sulfate into bovine nasal cartilage was investigated. The rapid breakdown of matrix caused by partially purified catabolin had little affect on the incorporation of [3H]amino acids but there was inhibition of [35S]sulfate uptake. While the 35S-labelled material released into the medium was largely incapable of aggregation with hyaluronate, this was only a small part (less than 10%) of the total incorporated. The principal inhibitory action was in the formation of large molecular size material (guanidinium chloride extractable). The amount of newly synthesized glycosaminoglycans (GAG) during the 8 day culture period was too low (less than 0.8%) to influence the very rapid breakdown of the matrix under catabolin stimulation. Cartilage organ cultures recovered from inhibition of [35S]sulfate incorporation and from the catabolic stimulation after removal of catabolin. It is suggested that the two properties of the catabolin preparation demonstrated in this study may work synergistically both in causing and prolonging cartilage damage in vivo.