Modulation of glycosaminoglycan production and antithrombin III binding by cultured aortic endothelial cells treated with 4-methylumbelliferyl-beta-D-xyloside.

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Abstract
The interaction between antithrombin III and heparinlike glycosaminoglycan molecules present on the vascular surface seems to play a significant role in the regulation of coagulation. We have tested the hypothesis that altered synthesis of glycosaminoglycans by endothelial cells could influence this interaction by using 4-methylumbelliferyl-beta-D-xyloside for metabolic perturbation of glycosaminoglycan production. Incubation of purified porcine 125I-antithrombin III with cultured porcine aortic endothelial cells demonstrated specific, time-dependent, saturable binding of this protease inhibitor to the endothelial cell surface with antithrombin III concentration at half-maximal binding of approximately 40 nM. This binding was displaced by heparin and was completely abolished by selective removal of heparan sulfate from cells with heparitinase, indicating that antithrombin III binds to heparan sulfate on the surface of endothelial cells. Incubation of cell cultures with beta-D-xyloside resulted in a reduct...