Thromboxane
From Free net encyclopedia
Thromboxane is a member of the family of lipids known as eicosanoids. It is produced in platelets by thromboxane synthetase, which is produced from the endoperoxides by the cyclooxygenase (COX) enzyme from arachidonic acid.
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Thromboxane is a vasoconstrictor, potent hypertensive agent, and facilitates the clumping of platelets. It is in homeostatic balance in the circulatory system with prostacyclin, a related compound. The widely-used drug aspirin acts by inhibiting the ability of the COX enzyme to synthesize the precursors of thromboxane within platelets.
Thromboxane is named for its role in clot formation (thrombosis). Thromboxane A2 (TXA2) produced by activated platelets has prothrombotic properties by stimulating activiation of new platelets as well as increased platelet aggregation. The latter is achieved by mediating expression of the glycoprotein complex GP IIb/IIIa in the cell membrane of platelets. Circulating fibrinogen binds these receptors on adjacent platelets, further strengthening the clot.