目的 探讨岩藻聚糖硫酸酯FV对大鼠的抗凝血作用及其机制。方法 以20、10、5、2.5、1.25、0.63 mg/kg尾iv给予Wistar大鼠，给药15 min后，采血测定大鼠凝血功能-凝血酶原时间（PT）、凝血酶时间（TT）、纤维蛋白原（Fib）、活化部分凝血活酶时间（APTT），确定量效关系；以5 mg/kg尾iv给予Wistar大鼠，给药0、7.5、15、30 min以及1、2、4、6、12、24 h后采血测定大鼠凝血功能，确定时效关系，并测定5、2.5、1.25 mg/kg剂量下FV的生物活性半衰期；以发色底物法检测在抗凝血酶Ⅲ（AT-Ⅲ）或肝素辅因子Ⅱ（HC-Ⅱ）存在下，FV对凝血酶（Ⅱa）、活化的凝血因子X（Xa）、活化的凝血因子IX（IXa）等的作用。结果 FV 0.63 mg/kg能显著延长APTT和TT，剂量高于10 mg/kg时PT显著延长，Fib显著降低，具有明显的剂量相关性。FV 5 mg/kg能够在4 h内显著延长APTT和TT，药后60 min内显著延长PT，具有明显的时间相关性。FV 5、2.5、1.25 mg/kg的抗凝效应均以一级动力学的方式消除，药效衰减速率常数（K）分别为0.013、0.019、0.048 min^-1，抗凝效应半衰期（t_l/2）分别为53.3、36.5、14.4 min。FV对Ⅱa、Xa、IXa无明显抑制作用；对Xa内源性激活复合物的形成具有明显抑制作用，IC₅₀为7.8 μg/mL，且不依赖于AT-Ⅲ和HC-Ⅱ；依赖于AT-Ⅲ，FV对Xa外源性激活复合物的形成具有抑制作用，IC₅₀为11.6 μg/mL。结论 FV以Xa内源性激活复合物为主要作用靶点，显著抑制该复合物的激活，发挥良好的抗凝活性，量效、时效关系明确。

Objective To explore the anticoagulant effect of fucus vesiculosus FV on rats and its mechanism. Methods The Wistar rats were injected intravenously with 20, 10, 5, 2.5, 1.25, and 0.63 mg/kg. After 15 min, the blood was collected to determine the dose-effect relationship between PT, TT, Fib, and APTT. The Wistar rats were injected intravenously with 5 mg/kg. The blood coagulation function was determined after 0, 7.5, 15, 30 min, 1, 2, 4, 6,12, and 24 h, for determining the time-effect relationship. The half-life time of biological activity of FV was measured at doses of 5, 2.5, and 1.25 mg/kg. The activity of coagulation factors was detected by chromogenic substrate method, such as Ⅱa, Xa, IXa, and so on, in the presence of Heparin Cofactor Ⅱ (HC-Ⅱ) or Antithrombin Ⅲ (AT-Thrombin Ⅲ). Results APTT and TT were significantly prolonged by FV at 0.63 mg/kg. PT was significantly prolonged when the dose was higher than 10 mg/kg, and Fib was significantly decreased. And the changes of these parameters had obvious dose-dependent. FV 5 mg/kg could significantly prolong APTT and TT within 4 h and PT within 60 min, which was time-dependent. The anticoagulant effects of FV 5, 2.5, and 1.25 mg/kg were eliminated by first-order kinetics. The pharmacodynamic attenuation rate constants (K) were 0.013, 0.019, and 0.048 min^-1, and the half-life times of anticoagulant effects were 53.3, 36.5, and 14.4 min, respectively. FV had no obvious inhibitory effect on thrombin (Ⅱa), activated factor X (Xa), and activated factor IX (IXa), and had obvious inhibitory effect on the formation of endogenous activation complex of Xa with IC₅₀=7.8 μg/mL, independently of AT-Ⅲ and HC-Ⅱ. Depending on AT-Ⅲ, FV had inhibitory effect on the formation of exogenous activation complex of Xa with IC₅₀=11.6 μg/mL. Conclusion FV takes the endogenous activation complex of Xa as the main target, inhibits the activation of the complex significantly, exerts good anticoagulant activity, and has a clear dose-effect and time-effect relationship.

R285.5

国家科技重大新药创制项目（2015ZX09501004）；天津市科技计划项目（17ZXXYSY00020）