Final answer:
Tissue plasminogen activator (tPA) is used clinically to dissolve blood clots by converting plasminogen into active plasmin, which breaks down the fibrin in clots. It is effective in treating thrombotic strokes when used within a specific time after onset.
Step-by-step explanation:
The clinical substance used to dissolve blood clots is tissue plasminogen activator (tPA). During the process of fibrinolysis, the inactive protein plasminogen is converted into active plasmin, which gradually breaks down the fibrin of the clot.
Tissue plasminogen activator catalyzes this conversion and is not only released naturally by endothelial cells but is also employed as a pharmaceutical agent in treating conditions like thrombotic strokes. Thrombolytic agents like tPA need to be administered within a limited time window after the onset of a stroke to significantly improve a patient's prognosis. It is crucial to determine if a stroke is caused by a thrombus (clot) or a hemorrhage before treatment, as administering tPA in the case of a hemorrhage could be detrimental.