Extracellular Matrix of Cultured Bovine Aortic Endothelial Cells Contains

The extracellular matrix (ECM) of cultured bovine aortic endothelial cells (BAEs) was analyzed by immunoblotting and reverse fibrin autography and shown to contain type 1 plasminogen activator inhibitor (PAl-i ). Most PAl-i in the ECM formed complexes with exogenously added tissuetype plasminogen activator (tPA). demonstrating that this PAl-i was functionally active. The resulting tPA/PAI-1 complexes were recovered in the reaction solution. mdieating that the PAl-i in such complexes no longer bound to ECM. The PAl-i could not be removed by incubating ECM in high salt (2 mol/L NaCI), sugars (1 mol/L galactose. 1 mol/L mannose). glycosaminoglycans (10 mmol/L heparin. 10 mmol/L dermatan sulfate). or e-aminocaproic acid (0.1 mol/L). However, PAl-i could be extracted from ECM by treatment with either argi ne (0.5 mol/L) or potassium