Heparin inhibits the formation of endoperoxide metabolites in rat platelets: aspirin-like activity

Amounts of thromboxane A₂ (TXA₂) synthesized during the collagen-induced aggregation was much higher in citrated PRP than in heaprinized PRP implying that heparin might inhibit the synthesis of endoperoxide metabolites besides its anticoagulant action. Preincubation of citrated PRP with heparin resulted in dose dependent inhibition of the formation of TXA₂ and PGE₂. At the high concentration, heparin also inhibited the aggregation of citrated platelets induced by collagen indicating that heparin possesses aspirin-like activity. The significance of this finding is that the antithrombotic effect of heparin is probably due to not only its anticoagulant effect but also inhibition of the formation of arachidonic acid metabolites by platelets.