THE EFFECTS OF APROTININ ON CHROMOGENIC PEPTIDE SUBSTRATE AND OTHER ASSAYS FOR COMPONENTS OF THE COAGULATION, FIBRINOLYSIS AND PLASMA KALLIKREIN SYSTEMS

Plasma samples containing a range of aprotinin levels (0-400 KIU/ml) w ere tested in chromogenic peptide substrate assays for antithrombin II I, protein C, plasma kallikrein inhibition, plasminogen, antiplasmin, tissue plasminogen activator and plasminogen activator inhibitor. No e ffect on the antithrombin III assay was seen. Aprotinin produced signi ficantly reduced values in the assays for protein C, plasminogen and t issue plasminogen activator, and significantly increased values for ka llikrein inhibition, antiplasmin and plasminogen activator inhibitor. Immunochemical assays for plasminogen activator including a new assay (BIA-t-PA) and plasminogen activator inhibitor were not affected by ap rotinin. When plasma samples from patients undergoing cardiopulmonary bypass, with and without high dose aprotinin therapy, were tested in t he chromogenic substrate assay for plasminogen activator inhibitor, ma rkedly elevated apparent inhibitor levels were found in the aprotinin group.