Proteoglycan structure and metabolism in normal and osteoarthritic cartilage of guinea pigs

Sulfated proteoglycan structure and metabolism in osteoarthritic articular cartilage from the hind-limb joints of guinea pigs in which the disease had been surgically induced were evaluated and compared with those from nonoperated or sham-operated controls. In these studies, conducted on animals receiving high and low dietary levels of ascorbic acid, the effect of vitamin C on these variables was also examined. Sulfated proteoglycan biosynthesis per unit of DNA as reflected by in vivo uptake of 35S-sulfate was stimulated both by arthritic development and high dietary vitamin C. Under these conditions, the specific activities, 35S-cpm/micrograms uronic acid, of the proteoglycans were elevated. Neither arthritic development nor variation in dietary levels of vitamin C altered the structure of the proteoglycans. Two species of proteoglycans that exhibited the same electrophoretic mobilities in agarose/acrylamide gels, the same elution profiles on high performance liquid chromatography,, and the same galactosamine/glucosamine ratios were found in all normal and osteoarthritic cartilage specimens tested. The specific activities of these two specimens tested. The specific activities of these two species were dissimilar. In all samples, the larger of the two species had a higher specific activity.