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Multiplate® PAR-4 test is a reagent kit for use in platelet aggregation studies on the Multiplate® analyzer to evaluate the qualitative platelet function in species expressing PAR-4 receptors. In particular PAR-4 test can be used for determination of PAR-mediated aggregation in species that do not express PAR-1 (stimulated by TRAP-6).

Thrombin is one of the most potent platelet agonists. It interacts with 2 protease-activated receptors (PARs) on the surface of human platelets – PAR-1 and PAR-4. The expression profiles of PARs on platelets differ between humans and nonprimates. PAR-1 is believed to be the primary receptor for thrombin in humans. In contrast, mouse platelets for example lack PAR-1 and largely signal through PAR-4 in response to thrombin.

Reagents, Storage and Stability

  • MP0549: PAR-4 test, PAR-4 Agonist, 1 x 1.0 ml, lyophilized (20 mM) with 5 micro test tubes for aliquotation. PAR-4 test reagent is stable until the expiry date printed on the vial label when stored at 2-8°C, 14 days after reconstitution when stored at 2-8°C, 4 weeks when stored at < -20°C or 24 hours after thawing. If reconstituted reagent is not transferred into micro test tubes, the original vial should be stored in an upright position.

PAR-1 is believed to be the primary platelet receptor for thrombin in humans. This receptor is activated by TRAP-6 in Multiplate. In contrast to humans, several animal species (e.g., mice, dogs) lack PAR-1 receptors and largely signal through PAR-4 in response to thrombin. Even in humans, platelet PAR-4 receptors can be stimulated to trigger platelet activation and aggregation. In order to reach a similar extent of aggregation as with the TRAPtest, significantly higher concentrations of PAR-4 agonist have to be applied (645 µM for PAR-4 compared to 32 µM for TRAP-6).