Loading…
Nonenzymatic Free Radical-catalyzed Generation of Thromboxane-like Compounds (Isothromboxanes) in Vivo
The isoprostanes (IsoPs) are novel bioactive prostaglandin-like compounds produced in vivo by free radical-catalyzed peroxidation of arachidonyl-containing lipids. Previously, we have identified IsoPs containing F-type and D- and E-type prostane rings that are formed by reduction and rearrangement o...
Saved in:
Published in: | The Journal of biological chemistry 1996-09, Vol.271 (38), p.23185-23190 |
---|---|
Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | The isoprostanes (IsoPs) are novel bioactive prostaglandin-like compounds produced in vivo by free radical-catalyzed peroxidation of arachidonyl-containing lipids. Previously, we have identified IsoPs containing
F-type and D- and E-type prostane rings that are formed by reduction and rearrangement of IsoP endoperoxide intermediates,
respectively. We now explore whether thromboxane B 2 (TxB 2 )-like compounds, termed B 2 -isothromboxanes (B 2 -IsoTxs), are formed by rearrangement of IsoP endoperoxides. Detection of these compounds was carried out using a stable isotope
dilution mass spectrometric assay originally developed for quantification of cyclooxygenase-derived TxB 2 . Incubations of arachidonic acid with Fe/ADP/ascorbate for 30 min in vitro generated a series of peaks representing putative B 2 -IsoTx at levels of 62.4 ± 21.0 ng/mg arachidonate. Using various chemical modification and derivatization approaches, it
was determined that these compounds contained hemiacetal ring structures and two double bonds, as would be expected for B 2 -IsoTx. Analysis of the compounds by electron ionization mass spectrometry yielded multiple mass spectra similar to those
of TxB 2 . B 2 -IsoTxs are also formed esterified to phospholipids; oxidation of arachidonyl-containing phosphatidylcholine in vitro followed by hydrolysis resulted in the release of large amounts of these compounds. To explore whether B 2 -IsoTxs are also formed in vivo , a well characterized animal model of lipid peroxidation consisting of orogastric administration of CCl 4 to rats was used. Levels of B 2 -IsoTx esterified in lipids in the liver increased 41-fold from 2.5 ± 0.5 to 102 ± 30 ng/g of liver. In addition, circulating
levels of free compounds increased from undetectable ( |
---|---|
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.271.38.23185 |