Glycosaminoglycans of the rat incisor pulp

Abstract

1. 1. The continuously growing, dentinogenically active rat incisor is a suitable model for the biochemical as well as morphological study of the process of hard tissue deposition. Thus the glycosaminoglycans (acid mucopolysaccharides) of the rat incisor dental pulp have been isolated, separated, quantitated and characterized by means of a cetylpyridinium chloride (CPC)-cellulose micro-column technique. 2. 2. The total amount of hexosamine was found to be 4.8 μg/mg tissue dry weight. The dry weight of this loose connective tissue was 10% of the tissue wet weight. 3. 3. Four hexosamine-containing fractions were isolated from the CPC-cellulose columns: one glycoprotein- and keratan sulphate-containing fraction, one hyaluronate fraction, one fraction containing predominantly 4-sulphated chondroitin sulphate, and one fraction with predominantly 6-sulphated chondroitin sulphate. In maxillary incisor dental pulps the combined chondroitin sulphate fractions accounted for 75%, and the hyaluronate fraction for 12%, of the total hexosamine. This is consistent with earlier results obtained using electrophoretic methods. 4. 4. By means of epichlorohydrin triethanolamine (ECTEOLA)-cellulose chromatography, a minor keratan sulphate fraction could be found. 5. 5. The hexosamines in the hyaluronate and combined chrondroitin sulphate fractions were separated on Dowex 50W-X8 columns. In the former only glucosamine was found. In the latter galactosamine dominated, but a small amount of glucosamine (less than 10%) was also found. 6. 6. A “neutral MgCl 2 elution profile” indicated that the molecular weight rangr of the chondroitin sulphates was 4·10 4−7·10 4. 7. 7. An “acid MgCl 2 elution profile” for the combined chondroitin sulphate fractions was also obtained. This suggested a variation in the sulphate content of the chondroitin sulphate.