Plasma levels of von Willebrand factor and plasminogen activator in patients with arterial thromboembolism--with special reference to their correlation to the increased catabolism of both fibrinogen and platelets.

Abstract

Plasma levels of von Willebrand factor(vWF) and plasminogen activator(PA) in the plasma of venous blood before and after 5 minutes' venous occlusion were studied in 104 patients with various types of arterial thromboembolic disease and 30 age-matched healthy subjects. Levels of beta-thromboglobulin(beta-TG) were determined in plasma prior to the venous occlusion. In 29 patients and 7 control subjects, turnover of intravenously injected 125I-labeled fibrinogen was studied. Mean plasma levels of von Willebrand factor antigen(vWF: Ag) and ristocetin cofactor activity(vWF: RCo) were significantly higher in patients than in controls both before and after the venous occlusion. Mean plasma PA activity was significantly lower in patients than in controls both before and after the venous occlusion, but mean plasma PA antigen before the venous occlusion was significantly higher in patients than in controls. Plasma clearance of i.v. injected 125I-labeled fibrinogen was significantly accelerated, and the catabolic flux(j3x) of fibrinogen calculated according to a two-compartment model was significantly higher in patients than in controls. Significant relationships were observed between T1/2 of 125I-labeled fibrinogen and the following: plasma levels of vWF: Ag both before and after the venous occlusion, PA activities after the occlusion, PA antigen before the occlusion, and the net decrease in PA activities and the net increase in PA antigen as a result of the occlusion. Significant relationships were also observed between j3x of fibrinogen and the following: plasma levels of vWF: Ag both before and after the venous occlusion, vWF: RCo after the occlusion, PA activities after the occlusion, PA antigen before the occlusion, and the net decrease in PA activities resulting from the occlusion. Plasma levels of beta-TG, which were significantly higher in patients than in controls, were not correlated to plasma levels of vWF and PA or to parameters of fibrinogen turnover. These results suggest that the change in endothelial cell function is responsible for the abnormal plasma levels of both vWF and PA and for the acceleration of fibrinogen metabolism in patients with thromboembolic disease.