What powerful anticoagulant is released by basophils and mast cells?

Heparin is a powerful anticoagulant that is released by basophils and mast cells. Its primary function is to inhibit blood clot formation, thereby playing a significant role in maintaining normal blood flow and preventing excessive coagulation within the bloodstream. By binding to and inactivating thrombin and other clotting factors, heparin effectively prevents the formation of fibrin, which is essential for blood clotting.

In contrast, histamine, released mainly from mast cells during allergic reactions and inflammatory processes, is primarily a vasodilator, contributing to increased blood flow and permeability, rather than having a direct role in anticoagulation. Prothrombin and thrombin are integral parts of the coagulation cascade; prothrombin is a precursor to thrombin, which facilitates clot formation rather than preventing it. Hence, the unique role of heparin as an anticoagulant distinguishes it from the other substances listed.