tPA Function — MFDS Part 1 MCQ

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ModeratePhysiologytPA FunctionMFDS Part 1

During physiological fibrinolysis, endothelial-derived tissue plasminogen activator (tPA) primarily acts to:

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Correct answer: C — Convert fibrin-bound plasminogen to plasmin, promoting fibrin degradation

Explanation lettering: C = shown as A · E = shown as B · A = shown as C · B = shown as E

**A is correct.** Endothelial-derived tPA is a key initiator of physiological fibrinolysis. Its activity is enhanced when tPA and plasminogen are associated with fibrin, allowing conversion of plasminogen to plasmin. Plasmin then proteolytically degrades fibrin and contributes to clot dissolution. tPA does not activate the tissue factor–factor VII pathway or promote thrombin generation (B), and it does not stimulate platelet glycoprotein IIb/IIIa-mediated aggregation (C). Antithrombin inhibits thrombin and other activated coagulation factors, but tPA does not inhibit antithrombin (D). Vasoconstriction is mediated by factors such as endothelin and local neurovascular responses rather than being the primary action of tPA (E).

Reference: Electronic Medicines Compendium. Actilyse — Summary of Product Characteristics, section 5.1 Pharmacodynamic properties: Mechanism of action. Updated 8 May 2026. https://www.medicines.org.uk/emc/product/898/smpc