Studies on the mechanism of platelet aggregation and release reaction induced by collagen and adrenaline

Abstract The effect of hirudin on collagen- and adrenaline-induced platelet aggregation was studied in order to evaluate the possible role of thrombin formation in platelet aggregation. The results were compared with those obtained with heparin, dextran-sulphate and diethylaminoethyl-dextran (DEAE-dextran). Hirudin, heparin, dextran-sulphate and DEAE-dextran potentiated adrenaline-induced first and second wave platelet aggregation. Collagen-induced platelet aggregation was to various degrees inhibited by heparin, hirudin and DEAE-dextran. The results indicate that thrombin formation is not an essential step in adrenaline-induced platelet aggregation and release reaction but may to some extent be involved in collagen-induced platelet release.