Catabolism of hyaluronan in the knee joint of the rabbit.

Catabolism of hyaluronan was studied by injecting hyaluronan labelled with [125I]-tyramine cellobiose ([125I]-TC) into knee joints of rabbits. After endocytosis [125I]-TC remains intracellularly allowing localization of the site of catabolism. At 6 hours after injection 63% could be recovered in and around the joint, while at 48 hours 32% remained locally. Chromatography showed that 12% of the injected tracer was degraded in joint tissues at 6 hours, increasing to 33% at 24 hours. There was no apparent degradation within the joint fluid. No tracer was found in the regional lymph glands, but 16% of the injected tracer was detected in the liver at 24 hours. This investigation demonstrates that hyaluronan in the joint can be degraded both locally and in the liver.