METABOLIC TURNOVER OF SULFATED GLYCOSAMINOGLYCANS AND PROTEOGLYCANS IN RABBIT TEMPOROMANDIBULAR-JOINT CARTILAGES WITH EXPERIMENTALLY-INDUCED OSTEOARTHROSIS

Osteoarthrosis-like changes were induced by means of experimental disk perforation in the right temporomandibular joint of rabbits. The turn over of proteoglycans and glycosaminoglycans was studied 16 weeks late r, using (SO4)-S-35. Tissues were sampled 1 day and 7 days after injec tion of the sulfate. The corresponding tissues from the left untreated joint were used as controls. After isolation of the glycosaminoglycan s the incorporation of (SO4)-S-35 was estimated by scintillating count ing. The extracted proteoglycans were analyzed, using gel electrophore sis, and the distribution of radioactivity was determined by autoradio graphy, followed by densitometry. Both the synthesis and rate of degra dation of the proteoglycans were increased in the experimental disk, c ompared with those of the control. The net result of these metabolic c hanges seemed to be losses of small proteoglycans, whereas a slow incr ease in the number of larger ones may have occurred. The turnover rate s of 4- and 6-sulfate increased, although their ratio remained unchang ed at this stage of the osteoarthrosis-like process. In the condylar c artilage the turnover of large and small proteoglycans was also increa sed. The increase was most marked among those containing 6-sulfated ga lactosaminoglycans. The results concerning the experimental condylar c artilage indicated a decrease in the largest proteoglycan population, whereas the proportion of small proteoglycans was increased.