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Platelet phospholipids in hemostasis and thrombosis
10
THROMBOSIS RESEARCH
Suppl . VI,
1986
19
R.F.A. Zwaal, E.11. Severs, J. Kosing lkpt. of biochemistry, University of
Limburg,
Maastricht,
The Netherlands
Platelet phospholipids participate in different ways in the formation of a hemostatic plug or in the generation of a thrombus. On the one hand, platelet activation triggers a number of metabolic events, among which the inosicol lipid patnway leading to the formation of second messengers within the cell. On the other hand platelet stimulation may lead to a substantial in membrane architecture, accompanied by a significant alterdtion reorientation or phospholipids in the plane of the membrane. This process ledds to an increased exposure of negatively charged (i.e. procoagulant) phospholipids and explains why stimulated platelets can strongly enhance both the rate of factor X-- and the rate of prothrombin activation. ?loreover, studies on a patient with a bleeding disorder showed that these platelets were equally deficient in catalyzing both coagulant reactions and that ttiis was related to a defect in the lipid reorientation process accompanying platelet activation. The importance of platelet phospholipids in coagulation reactions can also be illustrated by experiments in which platelets are shown to promote prothrombin conversion by phospholipiddrpendent prothrombin activators from snake venoms.
THROMBOSIS RESEARCH
Suppl . VI,
1986
19
R.F.A. Zwaal, E.11. Severs, J. Kosing lkpt. of biochemistry, University of
Limburg,
Maastricht,
The Netherlands
Platelet phospholipids participate in different ways in the formation of a hemostatic plug or in the generation of a thrombus. On the one hand, platelet activation triggers a number of metabolic events, among which the inosicol lipid patnway leading to the formation of second messengers within the cell. On the other hand platelet stimulation may lead to a substantial in membrane architecture, accompanied by a significant alterdtion reorientation or phospholipids in the plane of the membrane. This process ledds to an increased exposure of negatively charged (i.e. procoagulant) phospholipids and explains why stimulated platelets can strongly enhance both the rate of factor X-- and the rate of prothrombin activation. ?loreover, studies on a patient with a bleeding disorder showed that these platelets were equally deficient in catalyzing both coagulant reactions and that ttiis was related to a defect in the lipid reorientation process accompanying platelet activation. The importance of platelet phospholipids in coagulation reactions can also be illustrated by experiments in which platelets are shown to promote prothrombin conversion by phospholipiddrpendent prothrombin activators from snake venoms.