Enhancement of prothrombin activation on platelets by endothelial cells and mechanism of activation of factor V.
Factor Xa-catalyzed prothrombin activation occurs on cellular surfaces, including those of vascular endothelial cells. In a reconstituted model, endothelial cells and platelets acted synergistically to maximally activate prothrombin in the presence of Factor Xa. Synergism was observed at platelet concentrations less than 1 X 10(8)/ml. Thrombin formation was required for optimal prothrombin activation by endothelial cells and Factor Xa, with thrombin serving as an activator of Factor V. These data provide additional support for the hypothesis that vascular endothelium is a physiologic surface for hemostasis.
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D002417:Cattle; D002450:Cell Communication; D004727:Endothelium / Q000166:cytology / Q000378:metabolism*; D005165:Factor V / Q000378:metabolism*; D005170:Factor X / Q000378:metabolism; D015951:Factor Xa; D006487:Hemostasis; D006801:Humans; D066298:In Vitro Techniques; D011516:Prothrombin / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism
D005165:Factor V; D011516:Prothrombin; D005170:Factor X; D013917:Thrombin; D015951:Factor Xa