Proteoglycans and Glycosaminoglycans of Epiphyseal Cartilage in Florid and Healing Low Phosphate, Vitamin D Deficiency Rickets

Abstract

The composition of proteoglycans and glycosaminoglycans in two portions of the rat epiphyseal growth cartilage in florid and healing low phosphate, vitamin D deficiency rickets was studied. The concentration of both chondroitin sulfate and keratan sulfate was reduced with about 25 per cent in the lower (mineralizing) part of the growth plate in healing rickets compared to the lower (hypertrophic) part in florid rickets. In all samples about 85 per cent of the chondroitin sulfate chains had a sulfate ester group in the fourth position. Both in florid and healing rickets only one main population of polydisperse proteoglycans was found. In florid rickets the capacity to form aggregates with hyaluronic acid was the same in the upper and lower parts of the growth plate. With the onset of mineralization in healing rickets, however, a substantial decrease in this aggregability was demonstrated. These results give further support to the hypothesis that proteoglycans and, especially, proteoglycan aggregates, play a role in the mineralization process.