Effects of rare earth metals on blood coagulation and fiblinolysis

稀土金属，包括镧（La）、铈（Ce）、钕（Nd）、钐（Sm）、铽（Tb）、镝（Dy）、铒（Er）和镱（Yb），作为新兴技术产业中的新工业材料而引人注目。尽管稀土金属的使用正在增加，但关于这些金属的生物效应的报道很少。因此，本研究旨在确定这些稀土金属对体外血液凝固的影响。通过Furie等人的方法（J.Biol.Chem.，251：3235，1976）并用Kawabata等的方法（Eur.J.Biochem.，一百七十二：La，Ce，Nd，Sm，Tb，Dy，在脑磷脂和Ca ~（2+）存在下，Er和Yb均能剂量依赖性地延长凝血活酶或高岭土诱导的正常人血浆凝血时间，并延长活化的X因子诱导的血小板聚集时间。结果表明，稀土元素La、Ce、Nd、Ce Sm、Tb、Dy、Er和Yb显示出其抗凝作用，其机制部分是抑制活化的因子X和凝血酶的酶活性。

The rare earth metals, including lanthanum (La) , cerium (Ce) , neodymium (Nd) , samarium (Sm) , terbium (Tb) , dysprosium (Dy) , erbium (Er) and ytterbium (Yb) , are remarkably noteworthy as new industrial materials in the pioneering technological industries.Although the use of rare earth metals is increasing, there are very few reports on the biological effects of these metals.Therefore, this study was designed to detetermine the effects of these rare earth metals on blood coagulation in vitro.The clotting assay was performed by the method of Furie et al. (J.Biol.Chem., 251 : 3235,1976) and the enzymatic activites were determined with the method of Kawabata et al. (Eur.J.Biochem., 172 : 17,1998) .La, Ce, Nd, Sm, Tb, Dy, Er and Yb prolonged the clotting time of normal human plasma in a dose-dependent manner when clotting was induced either by thromboplastin or by kaolin in the presence of cephalin and Ca2+.They also prolonged the activated factor X induced clotting time of platelet-rich plasma.The amidolytic activaties of activated factor X and thrombin progressively decreased with increasing amount of rare earth metals.These results suggested that the rare earth metals, La, Ce, Nd, Sm, Tb, Dy, Er and Yb, appear to show their anticoagulant effects with mechanisms in part the inhibition of the enzymatic activities of both activated factor X and thrombin.