Thromboxane A2
Thromboxane A2 (TXA2) is a lipid mediator that is produced by platelets. It is released from the phospholipid membrane when platelets are activated. TXA2's main role is to:
- Amplify platelet activation
- Recruit additional platelets to the site of injury
- Constrict blood vessels
- Increase platelet aggregation
- Promote hemostasis, vasoconstriction, and wound healing
TXA2 is produced from arachidonic acid through the action of several enzymes, including: Cyclooxygenase (COX, Thromboxane synthase.
TXA2 has a half-life of approximately 30 seconds. It is an unstable intermediate between the prostaglandin endoperoxides and thromboxane B2.
Recent evidence suggests that TXA2 is involved in the pathogenesis of myocardial ischemia. It can lead to cell death and extension of ischemic myocardial damage.
Plasma levels of TXA2 on admission are associated with no-reflow after primary percutaneous coronary intervention.
Inhibition of COX-2 is thought to lead to an imbalance between two key inflammatory mediators, raising levels of thromboxane A2 relative to prostaglandin E2. This in turn increases production of the proinflammatory signaling molecules, the cytokines TNF- alpha (tumor TNF - Tumor necrosis factor factor alpha) and IL-1b (interleukin-1 beta) which destroy joint cartilage.
In primary dysmenorrhea there is abnormal and increased secretion of pro-inflammatory prostaglandins, thromboxane A2, prostacyclin and leukotrienes, which in turn induce abnormal uterine contractions similar to the way they induce contractions in labor.
Bromelain can reduce levels of thromboxane A2
PD- Protectin D1 / Neuroprotectin inhibits the platelet-aggregating action of thromboxane A2 thereby blocking the platelet aggregations responses to agents that depend on platelets to release thromboxane A2.
Inhibition of thromboxane A2 biosynthesis in vitro by the main components of Crataegus oxyacantha (Hawthorn) flower heads.
Cordyceps : Cordycepin, an active constituent in cordyceps, inhibits collagen-induced platelet aggregation by lowering calcium ion and thromboxane A2 activities.