A modification of an anti-Xa assay for plasma heparin has been devised using a low
molecular weight dextran sulfate that competitively binds protein heparin neutralizers
and displaces masked heparin. The addition of 0.12 mg dextran sulfate per ml of plasma
permits heparin, neutralized by the products of platelet aggregation, to recover full
functional activity against Xa. The assay will permit a more accurate assessment of
both exogenous plasma heparin and endogenous liepaiin-like activity in blood samples
collected with varying techniques. A further modification is proposed employing polybrene
to neutralize the plasma heparin-like material providing a concurrent control for
each sample that increases accuracy by eliminating the effect of varying AT-III levels
which have anti-Xa activity.
Keywords
Heparin - Antithrombin III - Dextran sulfate - Polybrene
