Fibrin (Factor Ia) (Last Updated - 3/30/2005)
-formed via activation of fibrinogen (Factor I) --> this reaction is catalyzed by calcium (Factor IV) & thrombin (Factor IIa)
-fibrin in turn takes part in the formation of the fibrin plug (clot) --> this reaction is catalyzed by Factor XIIIa
-click here to view an image of the clotting cascade
-also involved in the clot lysis process --> plasmin digests fibrin (Ia)
-has binding sites for either:
A) Plasminogen / Plasmin
B) Alpha-2-Anti-Plasmin
C) Thrombolytics (Ex.) t-PA)
-each of these compete for the Fibrin (Ia) binding site
A) If Plasminogen / Plasmin wins --> clot lysis
B) If Alpha-2-Anti-Plasmin wins --> clot lysis inhibited
C) If thrombolytics win --> clot lysis
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References:
Goodman & Gilman's: The Pharmacologic Basis Of Therapeutics - 10th Edition - 2001. Chapter 55.