title: Role of newly formed platelets in thrombus formation in rat after clopidogrel treatment: comparison to the reversible binding P2Y₁₂ antagonist ticagrelor.
abstract: Platelet P2Y₁₂ receptors play an important role in arterial thrombosis by stimulating thrombus growth. Both irreversibly (clopidogrel) and reversibly binding (ticagrelor, AZD6140) P2Y₁₂ antagonists are clinically used for restricted periods, but possible differences in platelet function recovery after drug cessation have not been investigated. We treated WKY rats with a single, high dose of 200 mg/kg clopidogrel or 40 mg/kg ticagrelor. Blood was collected at different time points after treatment. Flow cytometry confirmed full platelet protection against ADP-induced αIIbβ₃ activation shortly after clopidogrel or ticagrelor treatment. At later time points after clopidogrel treatment, a subpopulation of juvenile platelets appeared that was fully responsive to ADP. Addition of ticagrelor to clopidogrel-treated blood reduced αIIbβ₃ activation of the unprotected platelets. In contrast, at later time points after ticagrelor treatment, all platelets gradually lost their protection against ADP activation. Perfusion experiments showed abolishment of thrombus formation shortly after clopidogrel or ticagrelor treatment. Thrombus formation on collagen was determined under high shear flow conditions. At later time points, large thrombi formed in the clopidogrel but not in the ticagrelor group, and unprotected, juvenile platelets preferentially incorporated into the formed thrombi. However, platelets from both groups were still similarly reduced in assays of whole blood aggregation. Conclusively, recovery of rat platelet function after ticagrelor differs mechanistically from that after clopidogrel. This difference is masked by conventional platelet aggregation methods, but is revealed by thrombus formation measurement under flow. Juvenile platelets formed at later time points after clopidogrel treatment promoted thrombus formation.
authors.affiliation: Dept. of Biochemistry, CARIM, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands. Marijke.Kuijpers@maastrichtuniversity.nl
authors.forename: Marijke J E
authors.initials: MJ
authors.lastname: Kuijpers
authors.forename: Remco T A
authors.initials: RT
authors.lastname: Megens
authors.forename: Elham
authors.initials: E
authors.lastname: Nikookhesal
authors.forename: Marion A H
authors.initials: MA
authors.lastname: Feijge
authors.forename: J G R
authors.initials: JG
authors.lastname: De Mey
authors.forename: Mirjam G A
authors.initials: MG
authors.lastname: oude Egbrink
authors.forename: J J J
authors.initials: JJ
authors.lastname: van Giezen
authors.forename: Johan W M
authors.initials: JW
authors.lastname: Heemskerk
mesh_terms: D000241:Adenosine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D000077144:Clopidogrel; D019610:Cytoprotection / Q000187:drug effects; D015539:Platelet Activation / Q000187:drug effects; D011485:Protein Binding; D058921:Purinergic P2Y Receptor Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D051381:Rats; D011921:Rats, Inbred WKY; D013927:Thrombosis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000077486:Ticagrelor; D013988:Ticlopidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D058921:Purinergic P2Y Receptor Antagonists; D000244:Adenosine Diphosphate; D000077144:Clopidogrel; D000077486:Ticagrelor; D000241:Adenosine; D013988:Ticlopidine