Anticoagulant activities of lung and mucous heparins

It is generally assumed that heparins prepared from different tissues have equivalent actions. However, significant differences were found between lung and mucosal heparins when they were examined in an anti-Factor Xa assay, both in vivo and in vitro . These differences were not seen when the heparins were assayed by an APTT assay. With both types of heparin, anti-Xa activity increased with low molecular weight fractions, while the APTT activity decreased. However, with lung heparin the specific activities by anti-Xa assay were much lower at all molecular weights examined. It is believed that these observations have important implications for the assay and clinical use of heparin.