Thrombin is the last enzyme in the clotting cascade functioning to cleave fibrinogen to fibrin and potentiates the procoagulation process by activating factors V, VIII, XI, and XIII.
1 Conversely, thrombin aids the anticoagulant process by activating protein C.
2 Activated protein C inhibits activated factors V and VIII ultimately down-
regulating further thrombin production. Thrombin is often used as a potent platelet activator
in vitro. Platelet responses to thrombin are mediated through protease-
activated receptors (PARs).
3 Thrombin-
mediated signaling regulates a diverse range of metabolic processes including activation of phospholipases in platelets, endothelial cells, and cardiac myocytes.
4