Interactions Between Platelets and the Coagulation System

These events amplify the initating stimulus and lead to explosive thrombin generation and fibrinformation. Platelets can also sustain the procoagulant response by protecting the bound coagulation enzyme complexes from inactivation/inhibition. This overall process provides for rapid and localized clot formation Thrombin generation at the surface of platelets adhered to and activated at sites of vascular injury is central to formation of an insoluble fibrin clot and localized cessation of bleeding. Those platelets that actively regulate thrombin formation can be defined by: (1) a discrete population of young platelets expressing an increased density of adhesion molecules; (2) expression of specific, coagulation protein receptors; and (3) release of a number of hemostatically-active components including a unique and highly procoagulant factor Va molecule.