Xi M, Béguin S, Hemker H C
Department of Biochemistry, University of Limburg, Maastricht, The Netherlands.
Thromb Haemost. 1989 Sep 29;62(2):788-91.
The individual importance of each of the four vitamin K-dependent clotting factors on the generation of prothrombinase activity in the plasma of orally anticoagulated patients has been investigated. Addition of purified factors VII, IX or X to plasma from deeply anticoagulated patients (International Normalized Ratio 2.8-4.8) did not influence the amount of prothrombinase activity or the amount of thrombin formed. Only the prothrombin level in the plasma determines the course of thrombin generation. Addition of increasing amounts of purified factor II, VII, IX or X to plasmas deficient in respectively factor II, VII, IX or X showed that the prothrombinase activity increases linearly with the concentration of factor II added and that the concentration below which the factors VII, IX and X start to have a measurable effect on prothrombinase activity are 5%, 20%, and 30%, respectively. Half maximal prothrombinase activity was found at about 1% factor VII, 5% factor IX and 8% factor X respectively. From these observations we conclude that primarily the variation in factor II level determines thrombin generation and hence presumably the antithrombotic effect of oral anticoagulant therapy. It therefore seems likely that, for the control of oral anticoagulant therapy, tests that reflect factor II activity would be suitable.
已对口服抗凝剂患者血浆中四种维生素K依赖性凝血因子各自对凝血酶原酶活性生成的个体重要性进行了研究。向深度抗凝患者（国际标准化比值2.8 - 4.8）的血浆中添加纯化的因子VII、IX或X，不会影响凝血酶原酶活性的量或形成的凝血酶的量。血浆中只有凝血酶原水平决定凝血酶生成的过程。向分别缺乏因子II、VII、IX或X的血浆中添加越来越多的纯化因子II、VII、IX或X，结果显示凝血酶原酶活性随添加的因子II浓度呈线性增加，并且因子VII、IX和X开始对凝血酶原酶活性产生可测量影响的浓度分别为5%、20%和30%。分别在约1%因子VII、5%因子IX和8%因子X时发现凝血酶原酶活性达到最大值的一半。从这些观察结果我们得出结论，主要是因子II水平的变化决定凝血酶生成，因此大概也决定口服抗凝治疗的抗血栓形成作用。所以，对于口服抗凝治疗的控制，反映因子II活性的检测似乎是合适的。
