Assay characteristics and fibrin affinity of plasminogen activators of the intrinsic fibrinolytic system.
Plasminogen activators (PA) in the euglobulin fraction of dextran sulfate activated plasma (DS-EF) were assayed on fibrin plates. Activity related to tissue plasminogen activator (t-PA) or urokinase (u-PA) was quantified by antiserum inhibition. The DS-EF contained 30% t-PA, 30% u-PA and 40-50% activity unrelated to t-PA or u-PA. The latter was completely inhibited by 1.7 mumol/1 C1-inhibitor (C1INH), the two former were less sensitive. Addition of flufenamate to the DS-EF (DS-EF/Fluf) from normal and two factor XII (F XII)-deficient plasmas increased their activities to the same high level. More than 50% of the activity was unrelated to t-PA or u-PA, 30-40% was u-PA and 5-10% t-PA related. After addition of fibrinogen to DS-EF/Fluf and clotting with thrombin, the remaining solution contained only about 30% of the total activity, including less than 10% u-PA. The epsilon-aminocaproic acid inhibition pattern obtained with the DS-EF was uniform, and thus different from the biphasic pattern obtained with the low fibrin affinity PA, two-chain urokinase. Thus, both the plasma u-PA and the major unidentified PA in plasma have affinity for fibrin.
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D000328:Adult; D005591:Chemical Fractionation; D003174:Complement C1 Inactivator Proteins / Q000494:pharmacology; D016264:Dextran Sulfate; D003911:Dextrans; D004305:Dose-Response Relationship, Drug; D005069:Evaluation Studies as Topic; D005337:Fibrin / Q000378:metabolism*; D005342:Fibrinolysis / Q000187:drug effects; D005439:Flufenamic Acid; D006801:Humans; D007158:Immunologic Techniques; D008297:Male; D008722:Methods; D009994:Osmolar Concentration; D010960:Plasminogen Activators / Q000378:metabolism*; D012712:Serum Globulins / Q000097:blood
D003174:Complement C1 Inactivator Proteins; D003911:Dextrans; D012712:Serum Globulins; D005439:Flufenamic Acid; D005337:Fibrin; D016264:Dextran Sulfate; D010960:Plasminogen Activators