中华眼镜蛇毒对大鼠凝血功能的影响

Effect of Naja atra venom on blood coagulation in rats

目的研究中华眼镜蛇毒对大鼠凝血功能的影响。方法体外实验采用中华眼镜蛇毒及其分离峰与大鼠全血孵育,测定血栓弹力图;体内采用尾静脉或肌肉注射眼镜蛇毒,取不同时间点全血测定血栓弹力图;取体内外实验分离的血浆测定LDH活力、血红蛋白、vWF、P-selectin含量并采用酶切发色底物法测定凝血相关酶活性。结果体内外实验结果表明,眼镜蛇毒及其部分分离峰可明显引起大鼠凝血功能的异常,表现为凝血因子减少、纤维蛋白原水平低下、血小板功能减弱;同时大鼠血浆血红蛋白含量及LDH活力显著升高。体外实验中眼镜蛇毒及其部分分离峰可显著下调酶切凝血酶及纤溶酶底物活性。体内实验中肌肉注射后血浆中P-selectin含量0.5 h时显著升高,酶切凝血因子Ⅹa底物活性6 h内显著上调;尾静脉注射后血浆酶切凝血酶底物活性2 h内显著上调,6 h内vWF含量明显升高。结论中华眼镜蛇毒能明显引起大鼠凝血功能的异常,其作用主要与激活凝血系统导致凝血因子消耗、纤维蛋白原减少以及血小板消耗等有关。

Objective To explore the effect of Naja atra venom on blood coagulation in rats.Methods Whole blood was incubated with Naja atra venom or various fractions in vitro and a thromboelastogram was obtained.In an in vivo experiment,Naja atra venom was injected via the tail vein or intramuscularly and whole blood samples were collected at various time points to obtain the thromboelastogram.LDH,hemoglobin,vWF,and P-selectin were measured in plasma.The activity of coagulation-related enzymes in plasma was measured by the chromogenic substrate method.Results The in vitro and in vivo result showed that Naja atra venom and some of its fractions obviously induced an abnormality in the coagulation function in rats,which was characterized by a lack of coagulation factors,low level of fibrinogen,and lowering of the platelet count and function,while the plasma hemoglobin content and LDH activity were increased significantly.In vitro,Naja atra venom and its fractions significantly decreased the enzymatic activities of cleaving S2238 and S2251.In vivo,after intramuscular injection,the content of P-selectin was significantly increased at 30 min and the enzymatic activity of cleaving S2765 was significantly increased within 6 h.After tail vein injection,the enzymatic activity of cleaving S2238 was increased significantly within 2 h and vWF content was increased obviously within 6 h.Conclusions Naja atra venom induces an obvious abnormality in the blood coagulation function of rats.Its effect is mainly related to the consumption of coagulation factors and fibrinogen caused by activation of the coagulation system and the consumption of platelets.