Assay for the quantitative in vitro determination of platelet function triggered by TRAP-6. Thrombin receptor activating peptide-6 (TRAP-6) is a potent platelet activator and stimulates platelet aggregation via the thrombin receptor PAR-1.
Thrombin is capable of activating platelets, which is mediated primarily by the hydrolysis of a G-protein-coupled receptor on the platelet membrane, referred to as protease-activated receptor 1 (PAR-1) and a second receptor (PAR-4) that expresses a lower sensitivity to thrombin.1 Activation by thrombin results in cross linked platelet aggregation as fibrinogen strands bind to glycoprotein IIb/IIIa receptors. Upon activation the components of the GPIIb/IIIa receptors physically alter their conformation producing the high affinity fibrinogen binding site GPIIb/IIIa on the platelet membrane. In order to analyze platelet function triggered via the thrombin receptor commonly a peptide, which stimulates the PAR-1 receptor is used (SFLLRN = TRAP-6).2 This allows to test for platelet function activated by the PAR-1 receptor, without triggering fibrin formation in the sample, which would happen if thrombin was used as the agonist. TRAP-6 induced platelet aggregation may be reduced or absent in the presence of GPIIb/IIIa antagonists3 or in deficiency states of GpII/bIIIa receptors (Glanzman trombasthenia).4,5 TRAP-6 induced aggregation displays only a minor sensitivity for the inhibiting effects of acetylsalicylic acid 6,7,8 or ADP receptor antagonists.8,9,10,11
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