Stimulation of heparan sulphate release from cultured endothelial cells by plasmin

We investigated the effect of plasmin on the release of glycosaminoglycans (GAG) from bovine aortic endothelial cells in culture. Plasmin significantly increased the release of [35S]sulphate-labelled GAG (35S-GAG) from the cell layer, although plasminogen did not show such a stimulatory effect. The percentage of heparan sulphate in the released 35S-GAG (about 80%) was not changed by plasmin. Plasmin enhanced the detachment of endothelial cells from the monolayer only slightly. From these results, it was suggested that the local anticoagulant activity on endothelium mediated by the anticoagulant heparan sulphate will be increased by plasmin; the conversion of plasminogen to plasmin may be mediated by plasminogen activators released from thrombin-stimulated endothelial cells.