Brefeldin A inhibits thrombin receptor regeneration in human endothelial cells.

Endothelial cells, once stimulated with thrombin, are resistant to subsequent stimulation. After a recovery period of about 60 min the cells are sensitized again for activation by thrombin. The resensitization is independent of the receptor de novo synthesis.

Trypsin induced von Willebrand factor release from human endothelial cells in mediated by PAR-2 activation.

Nystedt and co-workers cloned in 1994 a second protease activatable receptor (PAR-2) that could be activated by trypsin but not by thrombin (1). In this study, we investigated whether trypsin induced stimulation of endothelial cells is linked to PAR-2 activation. We have found by mRNA analysis that endothelial cells of venous and arterial origin express both protease activatable receptors.