TURNOVER OF ANTI-PLASMIN, THE FAST-ACTING PLASMIN INHIBITOR OF PLASMA

Abstract

Human antiplasmin, the fast-acting plasma inhibitor in plasma, was purified to homogeneity and labeled with 125I. This material, which was indistinguishable from antiplasmin in plasma with respect to several physicochemical and functional properties, was injected i.v. and its turnover measured in control subjects and in patients undergoing thrombolytic therapy. In 8 control subjects (4 healthy persons and 4 patients with atherosclerosis), the following turnover characteristics were obtained: plasma radioactivity half-life 2.64 .+-. 0.32 days, fractional catabolic rate 0.53 .+-. 0.09 of the plasma pool/day, intravascular fraction 0.51 .+-. 0.05 and synthetic (catabolic) rate 1.4 .+-. 0.27 mg/kg per day. The half-life of the plasmin-antiplasmin complex in plasma, measured from the disappearance rate of labeled antiplasmin, plasmin or plasmin-antiplasmin complex during thrombolytic therapy was approximately 0.5 days.