Thromb Haemost 2002; 88(02): 186-193
DOI: 10.1055/s-0037-1613209
Review Article
Schattauer GmbH

Platelet Activation and Blood Coagulation

Johan W. M. Heemskerk
1  Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, The Netherlands
,
Edouard M. Bevers
1  Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, The Netherlands
,
Theo Lindhout
1  Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, The Netherlands
› Author Affiliations
Further Information

Publication History

Received 08 May 2002

Accepted 29 May 2002

Publication Date:
07 December 2017 (online)

Summary

Platelet activation and blood coagulation are complementary, mutually dependent processes in haemostasis and thrombosis. Platelets interact with several coagulation factors, while the coagulation product thrombin is a potent platelet-activating agonist. Activated platelets come in a procoagulant state after a prolonged elevation in cytosolic [Ca2+]i. Such platelets, e. g. when adhering to collagen via glycoprotein VI, expose phosphatidylserine (PS) at their outer surface and produce (PS-exposing) membrane blebs and microvesicles. Inhibition of aminophospholipid translocase and activation of phospholipid scramblase mediate the exposure of PS, whereas calpain-mediated protein cleavage leads to membrane blebbing and vesiculation. Surface-exposed PS strongly propagates the coagulation process by facilitating the assembly and activation of tenase and prothrombinase complexes. Factor IXa and platelet-bound factor Va support these activities. In addition, platelets can support the initiation phase of coagulation by providing binding sites for prothrombin and factor XI. They thereby take over the initiating role of tissue factor and factor VIIa in coagulation activation.