IRRADIATION OF BOVINE AORTIC ENDOTHELIAL-CELLS ENHANCES THE SYNTHESISAND SECRETION OF SULFATED GLYCOSAMINOGLYCANS

The effect of X-irradiation on the synthesis of heparan sulphate (HS) and chondroitin/ dermatan sulphate (CS/ DS) by bovine aortic endotheli al cells (BAEC), was studied by measuring the incorporation of [S-35]s ulphate and [H-3]glucosamine into newly synthesized glycosaminoglycan (GAG) chains. Medium extracts from irradiated cultures (5Gy) were foun d to contain approx. 130% more HS and 200% more CS/DS than unirradiate d controls. Smaller increases were observed in cellular extracts, irra diated cultures (5Gy) containing approx. 60% more HS and 100% more CS/ DS than unirradiated controls. Structural studies showed no significan t changes occurred upon irradiation in either the amounts or distribut ion of N-and O-sulphate groups in the HS molecule. Values for N-sulpha tion of 41.1% control and 41.5% irradiated (5Gy) were obtained, the co rresponding values for O-sulphation being 19.9% control and 20.2% irra diated. Isotope incorporation data indicated that sulphation of CS/DS may decrease after irradiation, however, analysis of chondroitin ABC l yase derived disaccharides showed no changes in the proportion of non- sulphated and O-sulphated disaccharides. The present study indicates t hat X-irradiation stimulates the synthesis and secretion of HS and CS/ DS proteoglycans (PGs) by BAEC. This could be relevant to many feature s which are found to be indicative of radiation-induced damage.