Inhibition of cyclooxygenase-independent platelet aggregation by low vitamin E concentration

Abstract

Platelet aggregation induced by threshold concentrations of agonists such as collagen, PAF or epinephrine was inhibited in vitro by 100 μM aspirin but was restored by stimulating platelets with high concentrations of collagen, PAF or by a combination of epinephrine and PAF. Incubating aspirin-treated platelets with 50-100 μM vitamin E or vitamin E acetate inhibited platelet aggregation by high concentrations of collagen and PAF and by the combination of epinephrine and PAF; platelet thromboxane A 2 formation was less than 10% in samples incubated with 100 μM aspirin. Apyrase, added to aspirin-treated platelet, did not influence platelet aggregation induced by epinephrine and PAF. The present study suggests that concentrations of vitamin E as low as 50-100 μM inhibit cyclooxygenase-independent platelet aggregation when combined with an inhibitor of the arachidonate pathway.