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Platelet Aggregation and Release by ADP and Thrombin: Evidence for Two Separate Effects of ADP on Platelets, Involvement of Fibrinogen in Release, and Mechanism of Inhibitory Action of Acetylsalicylic Acid
Author(s) -
Han P.,
Ardlie N. G.
Publication year - 1974
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1974.tb00478.x
Subject(s) - thrombin , platelet , chemistry , fibrinogen , clot retraction , aspirin , biochemistry , mechanism of action , biophysics , inhibitory postsynaptic potential , pharmacology , endocrinology , immunology , biology , in vitro
S ummary . The previously demonstrated roles of thrombin and fibrinogen in platelet interaction (Ardlie & Han, 1974) suggested a possible relationship between platelet aggregation and the release reaction. The present results show that a product of the action of thrombin on fibrinogen induced the release of platelet constituents. This activity was not inhibited by heparin. The thrombin‐fibrinogen reaction which occurs when platelets come into contact could be the cause of the subsequent release reaction. ADP was shown to be essential for the thrombin‐induced aggregation, but not the alteration in platelet morphology. Evidence of involvement of ADP in cell contact was obtained and it is possible that its role may be to facilitate aggregation through an effect on platelet surface charge. Thus, ADP induces aggregation through two distinct actions: (1) alteration of platelet morphology; and (2) reduction in net negative surface charge of platelets. Incubation of thrombin with aspirin inhibited its action on platelets and it is suggested that acetylation of thrombin (or prothrombin) by aspirin may account for the action of this compound on platelets. The significance of these observations and a possible mechanism for the release reaction is discussed.