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犬钩虫抗凝肽(Ancylostoma caninum anticoagulant peptide,AcAP5)是一种已报道的FXa抑制剂,它对防止血栓溶解的TAFIa具有很强的抑制作用,本文进一步研究rAcAP5的纤溶活性和溶栓活性。采用发色产物法测定rAcAP5对TAFIa的抑制作用,用比浊法测定rAcAP5对尿激酶(UK)诱导的纤维蛋白溶解时间的影响,通过血栓称重法进行体外溶栓实验和体内动静脉旁路溶栓实验。采用常规方法测定正常大鼠优球蛋白溶解时间(ELT),血浆纤维蛋白原含量和纤维蛋白降解产物(FDP)含量。rAcAP5浓度依赖地抑制TAFIa活性,其IC_(50)为63.7 nmol/L,为一个强的TAFIa抑制剂。rAcAP5(5-40 nmol/L)能够显著地加速尿激酶诱导纤维蛋白的溶解,缩短纤溶时间。rAcAP5能够提高尿激酶诱导的血栓减重(P<0.05),单独使用rAcAP5也能显著增加体外实验的血栓减重(P<0.05)。在大鼠体内的动静脉旁路模型中,单次静脉给予rAcAP5(50-200μg/kg)能够剂量依赖地增加血栓减重(P<0.01)。rAcAP5在有效剂量对正常大鼠的ELT、血浆纤维蛋白原含量和FDP含量均无明显影响。研究结果提示:rAcAP5是一个强效溶栓多肽,它可能通过抑制TAFIa的活性而在血栓表面具有溶栓活性,而不影响循环血液中的纤溶活性和纤维蛋白原含量。
Ancylostoma caninum anticoagulant peptide (AcAP5) is a reported FXa inhibitor that has a strong inhibitory effect on the prevention of thrombolytic TAFIa. In this paper, we further investigate the fibrinolytic activity and thrombolytic activity of rAcAP5. The inhibitory effect of rAcAP5 on TAFIa was determined by colorimetric method. The effect of rAcAP5 on urokinase (UK) -induced fibrinolytic time was determined by turbidimetry. The in vitro thrombolysis assay and in vivo arteriovenous shunt Thrombolytic experiment. Normal rats were used to determine the euglobulin lysis time (ELT), plasma fibrinogen and fibrin degradation products (FDP) content. rAcAP5 inhibited the TAFIa activity in a concentration-dependent manner with an IC 50 of 63.7 nmol / L, which is a potent TAFIa inhibitor. rAcAP5 (5-40 nmol / L) significantly accelerated urokinase-induced fibrinolysis and decreased fibrinolysis time. rAcAP5 can increase urokinase-induced thrombus weight loss (P <0.05), rAcAP5 alone can significantly increase thrombus weight loss in vitro (P <0.05). A single intravenous administration of rAcAP5 (50-200 μg / kg) increased thrombus weight-loss (P <0.01) in a dose-dependent manner in the arteriovenous bypass model in rats. rAcAP5 had no significant effect on ELT, plasma fibrinogen content and FDP content in normal rats. The results suggest that rAcAP5 is a potent thrombolytic polypeptide that may have thrombolytic activity on the thrombus surface by inhibiting the activity of TAFIa without affecting the fibrinolytic activity and fibrinogen content in circulating blood.