Proteoglycan synthesis and secretion by bovine aortic tissue in organ culture

The incorporation of 35S into proteoglycans (PG) of bovine aorta segments maintained in short term culture was investigated. The labeled PG were isolated by 4.0 M guanidinium chloride extraction and collagenase and elastase digestion and specific activities determined. The culture medium contained about 10% of the total uronate. In the sequential extraction of tissue PG, elastase treatment released the most uronate material. Guanidinium chloride extracted PG showed the highest degree of sulfation while the elastase solubilized PG had the lowest sulfate content. In the culture medium the highest specific activity was noted in heparan sulfate PG, followed by the chondroitin sulfates PG and then dermatan sulfate PG. Among the PG from tissue extracts, dermatan sulfate chains from guanidinium chloride extracted and collagenase solubilized PG showed similar specific activity. The highest specific activity of haparan sulfate was observed in the elastase solubilized PG. The specific activity of chondroitin sulfate chains was the lowest in all tissue PG preparations. These studies provide further evidence of the metabolic heterogeneity of aorta PG.