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, Volume 21, Issue 1–2, pp 195–202 | Cite as

Antagonists of PAF-acether do not suppress thrombin-induced aggregation of ADP-deprived and aspirin-treated human platelets

  • S. Adnot
  • D. Joseph
  • B. B. Vargaftig
Platelets and Thrombosis


Four chemically distinct PAF-acether antagonists were used to test the hypothesis that the cyclooxygenase and ADP-independent thrombin-induced aggregation of human platelets is due to PAF-acether. The compouds 48740 RP, CV-3988, BN 52021 and Ro 19-3704 inhibited aggregation by PAF-acether whereas 48740 RP also interfered with aggregation by arachidonic acid, U 46619, collagen and thrombin. Aspirin-treated platelets aggregated in response to PAF-acether and to 0.25 U/ml thrombin as much as control platelets in absence of detectable thromboxane A2, and were less responsive to 0.05–0.1 U/ml. Thrombin-induced aggregation of aspirin-treated platelets was unaffected by the PAF-acether antagnists BN 52021, CV-3988 and Ro 19-3704. In separate experiments, platelets were exposed for five min to convulxin, a glycoprotein extracted from a snake venom which depletes granular ADP and ATP. A combination of PGI2, aspirin and anticrotalid serum used to disaggregate allowed the recovery of approximately 80% free platelets, which failed to respond to PAF-acether but still aggregated in presence of thrombin. This residual ADP and cyclooxygenase-independent aggregation is not accountable for by the platelet formation of PAF-acether, since it was not modified by the latters' antagonists nor by platelet exposure to convulxin. Our results do not support the proposal that PAF-acether mediates a third pathway of human platelet aggregation.


Collagen Aspirin Arachidonic Acid Thrombin Platelet Aggregation 
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Copyright information

© Birkhäuser Verlag 1987

Authors and Affiliations

  • S. Adnot
    • 1
  • D. Joseph
    • 1
  • B. B. Vargaftig
    • 1
  1. 1.Untté des Venins-Unité Associée Institut Pasteur/INSERM n° 285 Department de Physiopathologie expérimentale Institut PasteurParisFrance

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