Thromboxane A2 (TXA2) is a type of
thromboxane that is produced by activated platelets and has prothrombotic properties: it stimulates activation of new platelets as well as increases platelet aggregation. This is achieved by increasing expression of the glycoprotein complex
GPIIb/IIIa on the cell membrane of platelets. The same effect is also achieved by
ADP in platelet stimulation, which is blocked by
clopidogrel. Circulating
fibrinogen binds these receptors on adjacent platelets, further strengthening the clot. Thromboxane A2 is also a known
vasoconstrictor and is especially important during tissue injury and inflammation. It is also regarded responsible for
Prinzmetal's angina.