Prostaglandins, Isoprostanes Thromboxanes

The autacoids comprise histamine, serotonin, angiotensin, neurotensin, NO (nitric oxide), kinins, platelet-activating factor, endothelins and the four families of traditional eicosanoids - the leukotrienes and three types of prostanoids i.e. prostaglandins, prostacyclins, and thromboxanes. Several other natural occurring molecules are sometimes called eicos-anoid, including the hepoxilins, resolvins, isofurans, isoprostanes, lipoxins, epoxyeicosatrienoic acids (EETs) and some endocannabinoids. However, not... 

LG formation can be enhanced in this system by inhibition of thromboxane synthase. Because prostaglandin synthases do not act on H2-isoprostanes, the relative yield of IsoK derived from H2-isoprostane formed in cells is expected to be similar to that found in vitro. 

Figure 3(a-c) demonstrates a comparison between the abnormal contraction in the SHR that develops spontaneously after the inhibition of endothelial cell NO and the contractions elicited by the thromboxane mimetic U46619 and E2 and F2 isoprostanes (8-iso-prostaglandin E2 and 8-iso-prostaglandin F2 ). It can be seen that the abnormality... 

Roberts, L. J., II, and J. D. Morrow. The isoprostanes Novel markers of lipid peroxidation and potential mediators of oxidant injury. Adv Prostaglandin Thromboxane LeukotRes 23(2), 1995 219-24. 

The complex mixture of regioisomers and stereoisomers structurally related to the endoperoxides and thromboxanes (prostaglandin-like compounds) produced from arachidonic acid and esterified to phospholipids and cholesterol are classified as isoprostanes. These compounds are used as markers of in vivo oxidative injury in biological systems and considered reliable because they are specific, stable and not affected by the lipid content of the diet (Chapter 13. E.4). However, these secondary oxidation products are produced in relatively small concentrations because they are derived from arachidonic acid, which is a minor polyunsaturated lipid compared to linoleic acid in biological samples. Very sensitive gas chromatography-mass spectrometric (GC-MS) and liquid chromatography-MS techniques are required to analyse isoprostanes in biological samples. 

---