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Encyclopedia > Thromboxane

Thromboxane is a member of the family of lipids known as eicosanoids. The two major thromboxanes are thromboxane A2 and thromboxane B2. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Thromboxane A2 is a thromboxane. ... Image File history File links Thromboxane_B2. ... Image File history File links Thromboxane_B2. ... Thromboxane B2 is a thromboxane. ... Figure 1: Basic lipid structure. ... In biochemistry, eicosanoids are a class of oxygenated hydrophobic hormones that largely function as paracrine mediators. ... Thromboxane A2 is a thromboxane. ... Thromboxane B2 is a thromboxane. ...


Thromboxane is named for its role in clot formation (thrombosis). Thrombosis is the formation of a clot or thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system. ...

Contents

Production

Enzymes and substrates associated with thromoboxane and prostacyclin synthesis.
Eicosanoid synthesis.
Eicosanoid synthesis.

It is produced in platelets by thromboxane-A synthase from the endoperoxides produced by the cyclooxygenase (COX) enzyme from arachidonic acid. Image File history File links Download high resolution version (1981x1687, 102 KB)Thromoboxane synthesis Drawn and released into the public domain by Nunh-huh. ... Image File history File links Download high resolution version (1981x1687, 102 KB)Thromoboxane synthesis Drawn and released into the public domain by Nunh-huh. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... A 250 ml bag of newly collected platelets. ... Thromboxane-A synthase, also known as thromboxane synthetase, is an enzyme that catalyses the conversion of prostaglandin H2 to thromboxane A2. ... Prostaglandin H2 is a type of Prostaglandin which is derived from arachidonic acid and is a precursor for many other biologically significant molecules: Eicosanoid synthesis. ... Cyclooxygenase (COX) is an enzyme (EC 1. ... Arachidonic acid (AA) is an omega-6 fatty acid 20:4(ω-6). ...


Functions

Thromboxane is a vasoconstrictor and a potent hypertensive agent, and it facilitates platelet aggregation. Vasoconstriction is the constriction of blood vessels, in other words, when the lumen narrows. ...


It is in homeostatic balance in the circulatory system with prostacyclin, a related compound. The mechanism of secretion of thromboxanes from platelets is still unclear. Homeostasis or homoeostasis is the property of an open system, especially living organisms, to regulate its internal environment so as to maintain a stable condition, by means of multiple dynamic equilibrium adjustments controlled by interrelated regulation mechanisms. ... For transport in plants, see Vascular tissue. ... Prostacyclin is a member of the family of lipid molecules known as eicosanoids. ...


Role of A2 in platelet aggregation

Thromboxane A2 (TXA2), produced by activated platelets, has prothrombotic properties, stimulating activiation of new platelets as well as increasing platelet aggregation.


Platelet aggregation 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. Fibrin is a protein involved in the clotting of blood. ... Coagulation is the thickening or congealing of any liquid into solid clots. ...


Pathology

It is believed that the vasoconstriction caused by thromboxanes plays a role in Prinzmetal's angina. Prinzmetals angina, also known as variant angina or angina inversa, is a syndrome typically consisting of angina (cardiac chest pain) at rest that occurs in cycles. ...


Suppression

The widely used drug aspirin acts by inhibiting the ability of the COX enzyme to synthesize the precursors of thromboxane within platelets. Aspirin, or acetylsalicylic acid (IPA: ), (acetosal) is a drug in the family of salicylates, often used as an analgesic (to relieve minor aches and pains), antipyretic (to reduce fever), and as an anti-inflammatory. ...


It inhibits the COX enzyme both non-competitively and irreversibly.


The side effect of this is that people who regularly take aspirin will suffer from excessive bleeding whenever the skin is perforated.


==External links== Wee inhibitors are more prone for inhibitions of Thromboxane and Histamine


  Results from FactBites:
 
NEJM -- Thromboxane biosynthesis and platelet function in type II diabetes mellitus (2086 words)
We therefore compared the excretion of a thromboxane metabolite and platelet function in 50 patients with Type II diabetes mellitus who had normal renal function and clinical evidence of macrovascular disease and in 32 healthy controls.
The fractional conversion of exogenous thromboxane B2 (infused at a rate of 4.5, 45.3, or 226.4 fmol per kilogram of body weight per second) to urinary 11-dehydro-thromboxane B2 was assessed in four patients, in whom it averaged 5.4 +/- 0.1 percent; this value did not differ from that measured in healthy subjects.
Picotamide, a combined inhibitor of thromboxane A2 synthase and receptor, reduces 2-year mortality in diabetics with peripheral arterial disease: the DAVID study.
Thromboxane definition - Medical Dictionary definitions of popular medical terms (213 words)
Thromboxane: A substance made by platelets that causes blood clotting and constriction of blood vessels.
Thromboxane A2 (TXA2) is active but is very unstable and has a half-life of only 30 seconds before it undergoes hydrolysis to form thromboxane B2 (TXB2) which is inactive.
The thromboxanes are derived from arachidonic acid and are related to prostaglandin.
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