Which statement best describes the mechanism of Tissue plasminogen activator (tPA) in myocardial infarction?

• A. A drug that breaks up blood clots
• B. A drug that slows heart rate
• C. A drug that reduces cholesterol
• D. A vasodilator used for migraines

Answer: (A)

tPA works by activating the body's fibrinolytic system to dissolve the clot. It does this by converting plasminogen, an inactive precursor in the blood, into plasmin. Plasmin is a protease that digests fibrin, the protein mesh that holds a thrombus together. By breaking down fibrin, the intracoronary clot causing the myocardial infarction is dissolved, restoring blood flow and limiting heart muscle damage. This mechanism is different from simply slowing heart rate, lowering cholesterol, or acting as a vasodilator for migraines, which do not involve promoting fibrinolysis.