Bode A P, Lust R M
Department of Pathology and Laboratory Medicine, East Carolina University School of Medicine, Greenville 27858.
Thromb Res. 1994 Mar 1;73(5):285-300. doi: 10.1016/0049-3848(94)90025-6.
The effect of platelet procoagulant activity in the Activated Coagulation Time (ACT) was measured in whole blood anticoagulated with various levels of heparin before or after reversal with protamine. Similar studies were carried out on blood anticoagulated with hirudin to distinguish procoagulant activity from heparin neutralization in platelet preparations. At 0.5-1.0 units/mL antithrombin activity with heparin or hirudin, the ACT was lowered progressively by the addition of increasing concentrations of lysed platelets to as much as 20 seconds below the baseline clotting time obtained with unanticoagulated blood samples. Neutralization of higher concentrations of heparin with protamine produced an ACT below baseline in the presence of lysed platelets. Aprotinin (400 KIU/mL) prolonged the ACT slightly in heparinized whole blood, but did not prevent the lowering of the ACT by lysed platelets to baseline or below. Recirculation of heparinized whole blood in a simulated cardiopulmonary bypass circuit generated platelet microparticles detected by flow cytometry. An increase in platelet microparticles was associated with a decrease in the amount of protamine needed to reach the baseline ACT in blood samples removed from the circuit at various time points during recirculation. A chromogenic anti-Factor Xa assay of heparin did not show a change with increasing microparticle concentration during recirculation. These findings indicate a masking of heparin activity by the procoagulant activity of platelet membrane microparticles that could affect reversal of heparin based on the ACT.
在使用鱼精蛋白进行肝素逆转之前或之后，用不同水平肝素抗凝的全血中测量了血小板促凝活性对活化凝血时间（ACT）的影响。对用水蛭素抗凝的血液进行了类似研究，以区分血小板制剂中的促凝活性和肝素中和作用。在肝素或水蛭素的抗凝血酶活性为0.5 - 1.0单位/毫升时，加入浓度不断增加的裂解血小板会使ACT逐渐降低，比未抗凝血样获得的基线凝血时间低至20秒。在存在裂解血小板的情况下，用鱼精蛋白中和较高浓度的肝素会使ACT低于基线。抑肽酶（400 KIU/毫升）在肝素化全血中使ACT略有延长，但不能阻止裂解血小板将ACT降低至基线或更低水平。在模拟体外循环回路中对肝素化全血进行再循环，通过流式细胞术检测到血小板微粒。血小板微粒增加与再循环期间不同时间点从回路中取出的血样达到基线ACT所需的鱼精蛋白量减少有关。再循环期间，肝素的发色抗Xa因子测定未显示随着微粒浓度增加而发生变化。这些发现表明血小板膜微粒的促凝活性掩盖了肝素活性，这可能会影响基于ACT的肝素逆转。
