Nhibitory and Anticoagulant Activities of Fractionated Heparins

Almost monodisperse heparin fractions (Rw/%r < 1.1) were obtained by gel filtration of a commercial heparin. These fractions were assayed for anticoagulant activity (thrombin times and APTT), chromogenic anti-factor Xa activity, inhibitory activity for the human classical complement pathway, carboxyl group content and total sulfate content. Linear relationships were observed between the molecular weight of the heparin fractions and the anticoagulant activities as determined by thrombin timeand APTTassay and the classical complement pathway inhibitory activity. On the other hand a hyperbolic-like relationship was observed between the molecular weight of the heparin fractions and the chromogenic anti-factor Xa activity. The heparin fractions did not show significant differences with respect to the carboxyl group and total sulfate content. Lowand high affinity heparin fractions were obtained by affinity chromatography using immobilized AT III. Highand low-affinity fractions greatly differed not only with respect to their APTT activity, but also where their complement-inhibitory activities were concerned. The latter in contrast to literature data available. These differences could not be explained by the observed differences in molecular weight of high and low affinity heparin respectively. INTRODUCTION Heparin, a physiological mixture of polysulfated glycosaminoglycans, has a number of biological effects (1). Most pronounced, so far, are the influence on different parts of the coagulation system and the inhibition