低分子量肝素对血凝及动,静脉血栓形成的影响

以标准肝素（ＳＨ）为原料经亚硝酸裂解制备的低分子量肝素（ＬＭＷＨ），给予同等抗Ｘａ单位剂量时，对凝血系统的影响较ＳＨ小，在治疗量下（１００ａｎｔｉ－ＸａＩＵ／ｋｇ）不增加出血倾向；体外实验表明，ＬＭＷＨ能有效地抑制ｃｈａｎｄｌｅｒ模型的血栓形成；体内实验表明，ＬＭＷＨ在１００～２００ａｎｔｉＸａＩＵ／ｋｇ范围内能有效地抑制大鼠动－静脉旁路、大鼠颈动脉电流损伤（ｉｖ，ｓｃ）和家兔颈静脉血栓模型的血栓形成，与参照品Ｆｒａｇｍｉｎ及ＳＨ的作用相似，ＬＭＷＨ在上述模型中的ＥＤ５０分别为：１５９，１８５（ｉｖ），１９３（ｓｃ），９１ａｎｔｉ－ＸａＩＵ／ｋｇ；研究还发现，ｓｃＬＭＷＨ吸收完全，给药后３ｈ的抗血栓作用与ｉｖ后１０ｍｉｎ相似，而ＳＨ的作用弱。提示ＬＭＷＨ保留了ＳＨ的抗血栓作用，降低了ＳＨ的出血副作用。

Effect of Low Molecular Weight Heparin on Coagulation System and Thrombosis

Low molecular weight haprin(LMWH) was obtained by controlled nitrous acid degradation of standard heparin(SH).It was demonstrated that 1) LMWH has less effect on coagulation system than SH;2) The anti-thrombotic potency of LMWH was weaker,compared to that of SH,in vitro;3) The effects of LMWH and Fragmin and SH on thrombosis vivo were similar to one another.The ED50 of LMWH in models of the arterovenous shunt,carotid thrombosis(iv,sc)and vein thrombosis were 159,185(iv),193(sc)and 91 Xa IU/kg,respectively,It was found that LMWH injected in vein and subcutaneousely had the same effect on carotid thrombosis model,but not to standard heparin.The findings suggest that LMWH remains the anti-thrombotic effect of SH,decreases the side effect of SH ,and is a potential anti-thrombotic agent.