Platelets play a central role in arterial thrombosis. Platelets adhere, activate, aggregate, and promote thrombus formation. As mentioned, platelets adhere to activated or denuded endothelial surfaces via bonds between vWF and P-selectin. The platelet membrane receptor glycoprotein Ib-IX (GpIb-IX) binds vWF (15). This bond tethers platelets to the surface, initiating adherence and subsequent aggregation. Platelets also bind exposed collagen, stabilizing the platelet plug and provoking the expression of GpIIb/IIIa and the release of adenosine 5'-diphosphate and thromboxane A2. These molecules act in an autocrine manner and lead to an amplification ofplatelet aggregation. Fibrinogen rapidly binds the GpIIb/ IIIa receptors and crosslinks the platelet plug simultaneously as thrombin and fibrin are produced by the coagulation cascade. Once thrombin is generated, it serves to further activate platelets (16).
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