The Inhibition by Plasma of Urokinase and Tissue Activator-Induced Fibrinolysis in Pregnancy and the Puerperium

Abstract

The activity of urokinase and tissue activator on fibrin plates was inhibited by plasma from women in the third trimester of pregnancy to a greater extent than by non-pregnant plasma. Pregnancy also inhibited the amidolytic activity of urokinase. The high molecular weight fractions of pregnancy plasma gel filtered on Sephadex G-200 showed comparable inhibitory activity against urokinase as fractions for non-pregnant plasma; in contrast with non-pregnant plasma, the lower molecular weight fractions of pregnancy plasma were markedly inhibitory against urokinase. Plasma exposed to lysine-Sepharose to remove plasminogen and then fractionated on Sephadex G-100 provided a pattern of three areas of inhibition against tissue activator similar to that seen in non-pregnant plasma. The urokinase-inhibitory activity of lower molecular weight fractions of plasma separated on Sephadex G-200 fell within 1 hr of delivery and fell further over the following 18 to 30 hr.