Felsch J S, Owen W G
Section of Hematology Research, Mayo Clinic and Foundation, Rochester, Minnesota 55905.
Biochemistry. 1994 Jan 25;33(3):818-22. doi: 10.1021/bi00169a024.
A recirculating Langendorff heart preparation is used to characterize the endogenous antithrombin associated reversibly with murine vascular endothelium. Rat hearts are perfused clear of blood and then recirculated with a physiological salt solution. Addition of heparin educes antithrombin activity continuously into the perfusate during 6 min of recirculation. This process contrasts with a more rapid equilibration of the system as assessed by displacement of [125I]thrombin with hirudin or with a heparin-antithrombin mixture. Perfusion of washed hearts with [125I]factor Xa, which evidences no significant binding to the coronary endothelium, identifies a minor fraction of the endogenous antithrombin that reacts immediately with factor Xa, i.e., at a rate indicative of heparin enhancement. This rapid-reacting antithrombin is not reproducibly detected with [125I]thrombin, which binds preferentially to thrombomodulin in this system. The amount of antithrombin reacting rapidly with factor Xa is too low to detect as a burst of antithrombin activity eluted into the perfusate when the hearts are perfused with heparin. It is concluded that the murine myocardial microvasculature harbors at least two pools of antithrombin, the minor of which is in an activated configuration characteristic of association with heparin. The major pool is in a more slowly accessible compartment or configuration.
使用循环式Langendorff心脏制备法来表征与小鼠血管内皮可逆结合的内源性抗凝血酶。将大鼠心脏灌注至无血，然后用生理盐溶液进行循环灌注。在循环灌注6分钟期间，加入肝素可使抗凝血酶活性持续释放到灌注液中。该过程与通过水蛭素或肝素 - 抗凝血酶混合物置换[125I]凝血酶评估的系统更快平衡形成对比。用[125I]因子Xa灌注洗净的心脏，结果表明其与冠状动脉内皮无明显结合，这确定了内源性抗凝血酶的一小部分会立即与因子Xa反应，即以表明肝素增强作用的速率反应。用[125I]凝血酶无法可重复地检测到这种快速反应的抗凝血酶，因为在该系统中[125I]凝血酶优先与血栓调节蛋白结合。与因子Xa快速反应的抗凝血酶量太少，以至于当用肝素灌注心脏时，无法作为洗脱到灌注液中的抗凝血酶活性爆发来检测。结论是，小鼠心肌微血管含有至少两个抗凝血酶池，其中较小的一个处于与肝素结合相关的活化状态。主要池处于较难接近的隔室或状态。
