Release of glycosaminoglycans from the endothelial cell surface by thrombin

Abstract

Heparan sulfate glycosaminoglycans released from endothelial cells have been demonstrated to have an anticoagulant potency. In the present study, the effect of thrombin on the release of ³⁵S-labeled glycosaminoglycans on the cultured endothelial cell surface has been examined. Thrombin significantly enhanced the release of ³⁵S-glycosaminoglycans in a dose-dependent fashion. At 10unit/ml of thrombin, the amount of released glycosaminoglycans was twice as much as that released by Hanks' solution alone. The release by thrombin reached a maximum up to one hour of incubation at 37°C. When thrombin was modified by diisopropylfluorophosphate or co-incubated with hirudin, its effect was completely abolished. Characterizations of ³⁵S-glycosaminoglycans showed that they consisted of heparan sulfate. A major part of ³⁵S-glycosaminoglycans released by thrombin was trichloroacetic acid-precipitable. Thrombin did not cause the release of ⁵¹Cr from radiolabeled endothelial cells.
These results indicate that thrombin can release heparan sulfate proteoglycans on the endothelial cell surface without any damage on the cells. Its effect was dependent on the dose and proteolytic activity.