[Regulation of the endothelial function by thrombomodulin and/or thrombin receptor]

Thrombin, the final product of blood coagulation cascade, shows several effect on the vessel-wall cells. However the effects may be regulated by several thrombin receptors on the endothelium. They include thrombomodulin (TM), protease-Nexin, heparin-like molecule-antithrombin III complex. These binding sites do not transduce the signal of thrombin. Especially TM converts thrombin from a procoagulant protease to an anticoagulant. Recently new thrombin receptor was identified on the endothelium and platelets. Through this receptor, thrombin induces activations both on platelet end-endothelium. In brief platelets aggregate and release several factors including serotonin, PDGF, platelet factor4, beta-thromboglobulin on the stimulation by thrombin. The endothelium release t-PA inhibitor; PAI-1, prostacyclin and endothelin. Thus the activations of these cells by thrombin is a key events in hemostasis, wound healing, inflammation, atherosclerosis and restenosis of coronary artery after PTCA.