Glycosaminoglycan depletion greatly raises the hydraulic permeability of rabbit joint synovial lining

The hydraulic resistance of the synovial lining of a joint is important for retention of intraarticular lubricant. The resistance has been attributed to synovial interstitial glycosaminoglycans. This was tested by depletion of hyaluronan and chondroitin sulphates from synovium in five rabbit knees in vivo under anaesthesia, using testicular hyaluronidase. The enzyme raised synovial permeability to fluid 5- to 7-fold - substantially more, in fact, than predicted by a recent model. The results prove that hyaluronan and/or chondroitin sulphate are important sources of hydraulic resistance in synovium.