Abstract
To evaluate the antithrombogenic activity of endothelium, we intravenously injected heparin (60U/kg) in patients with thrombotic tendency and healthy controls, and measured both plasma concentration of platelet factor 4(PF4) and β-thromboglobulin(βTG).
The plasma PF4 increased transiently 5 minutes after heparin injection, while βTG did not. PF4 bound to cultured human umbilical venous endothelial cell monolayer was also released by the incubation with heparin (1U/ml) in vitro.
As the heparin exerts its anticoagulant activities by potentiating the antithrombin III (AT III) against the coagulation factor proteinases, more increasing amounts of PF4 released from endothelium neutralize larger heparin-like molecules on the endothelium and decrease the antithrombogenic activities of endothelium.
We designated the heparin-releasable PF4 as ΔPF4 and βTG before heparin injection as pre-βTG respectively. It is assumed that ΔβF4 is one of a marker of the endothelial antithrombogenic activity and pre-βTG is a marker of the platelet activation in vivo.
In healthy controls, there was a direct corelation between pre-βTG and ΔPF4. The patients with thrombotic tendency (cerebral thrombosis, DM, rheumatoid disease, DIC, and malignancy) showed abnormal profile, that is high βTG with increased heparin releasable PF4.
In conclusion, heparin infusion test is appeared to be a useful method for the evaluation of the endothelial antithrombogenic activity.
