[Heparan sulfate biosynthesis in swine arterial wall: glycosylation and sulfation]

We investigated "in vitro" incorporation of labelled (14C) - or (35S) - precursors into microsomal heparan sulfate of pig aortic media-intima. Heparan sulfate, predominantly located on the external surface of smooth muscle cells, may conceivably provide a mean for the selective binding of plasma components to the arterial wall; functional implications of such binding, have been proposed in atherogenesis and thrombogenesis processes. We demonstrated the great metabolic activity of heparan sulfate chains. By evaluation of radioactivity incorporated into monosaccharides residues, we showed that sugar was quantitatively transferred from UDPGlcNAc 14C into endogenous glycosaminoglycans. The relationship between the N- and O-sulfation processes into heparan sulfate chains was studied after different time of sulfation by labelled sulfate nucleotide: PAP(35S). Our results outlined that preferential N-sulfation is obtained with short time exposures to labelled precursor, the O-sulfation occurring on previously N-sulfated heparan sulfate.