INFLUENCE OF DIFFERENT ANTICOAGULANTS ON PLATELET-AGGREGATION IN WHOLE-BLOOD - A COMPARISON BETWEEN CITRATE, LOW-MOLECULAR-MASS HEPARIN ANDHIRUDIN

Anticoagulants used for platelet function studies in vitro may affect platelet responsiveness. Tn the present study we compared the influenc e of three different anticoagulants, sodium citrate, low molecular mas s heparin, and recombinant hirudin, on platelet aggregation in whole b lood in vitro, using impedance aggregometry. ADP and collagen induced aggregation was significantly lower in citrated blood compared to hiru din treated blood, reflecting the importance of exctracellular calcium for platelet function. Inhibition of platelet aggregation by aspirin, was more pronounced in citrated blood compared to hirudin treated blo od, in agreement with the concept of artifactually enhanced thromboxan e generation in media containing low extracellular calcium levels. In blood anticoagulated with low molecular mass heparin, platelet aggrega tion to collagen tended to be enhanced as compared to hirudin treated blood, whereas platelet responses to ADP at a high concentration were slightly reduced. Of the anticoagulants investigated, the selective th rombin inhibitor hirudin is the most suitable anticoagulant for studie s of platelet aggregation in vitro in whole blood. (C) 1997 Elsevier S cience Ltd.