HIGH SHEAR-INDUCED PLATELET ACTIVATION AND INACTIVATION - THE IMPORTANCE OF METHODOLOGY

High shear platelet activation may be conveniently studied by forcing blood through a tine tilter in the filterometer. To achieve haemostasi s in vivo platelets are activated When haemostasis is achieved, inacti vation must follow. In the filterometer, activation occurs with filter blocking (first phase) and after 100 s inactivation ('rebleeding') ma y occur (second phase). We report the effect of different pressures, t emperatures, incubation times, anticoagulants and aspirin in this syst em Most 'rebleeding' occurred in citrate, followed by native blood, r- hirudin and low-molecular-weight heparin. Unfractionated heparin inhib ited 'rebleeding' whereas aspirin potentiated it. These and other find ings are technically and clinically relevant and contribute to an unde rstanding of the mechanisms involved in 'rebleeding' and hence perhaps in thrombogenesis.