Comparison of formation of D2/E2-isoprostanes and F2-isoprostanes in vitro and in vivo--effects of oxygen tension and glutathione.
The isoprostanes (IsoPs) are bioactive prostaglandin-like compounds derived from the free-radical-catalyzed peroxidation of arachidonic acid in vitro and in vivo. IsoPs possessing either an F-type prostane ring (F2-IsoPs) or D/E-type prostane rings (D2/E2-IsoPs) are formed depending on whether IsoP endoperoxide intermediates undergo reduction or isomerization, respectively. Little, however, is known regarding factors influencing the formation of various classes of IsoPs, particularly D2/E2-IsoPs. Thus, studies were undertaken to examine the formation of D2/E2-IsoPs in relation to F2-Isops both in vitro and in vivo. In peroxidizing rat liver microsomes, the formation of D2/E2-IsoPs increased in a time- and oxygen-dependent manner and correlated with F2-IsoP generation and loss of precursor arachidonic acid, although the absolute amount of D2/E2-IsoPs formed exceeded by over 5-fold the levels of F2-IsoPs formed. Surprisingly, however, in liver tissue from rats exposed to an oxidant stress, levels of F2-IsoPs were up to 10-fold greater than those of D2/E2-IsoPs, suggesting that an endogenous process causes IsoP endoperoxide reduction in vivo. Addition of glutathione (GSH) to peroxidizing microsomes at concentrations from 0.01 to 5 mM increased the formation of F2-IsoPs at the expense of D2/E2-IsoPs. Boiling of microsomes did not alter the effect of GSH. Formation of D2/E2-IsoPs in liver tissue in vivo was greatly enhanced compared to F2-IsoPs in rats depleted of GSH. Thus, GSH modulates the formation of different classes of IsoPs in vitro and in vivo. Other thiols, including beta-mercaptoethanol, dithiothreitol, and cysteine, were able to substitute for GSH. These studies indicate that GSH promotes F2-IsoP formation and diminishes D2/E2-IsoP levels in vitro and in vivo by causing reduction of IsoP endoperoxides.
Morrow
J D
JD
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6602, USA. Jason.Morrow@mcmail.vanderbilt.edu
Roberts
L J
LJ
Daniel
V C
VC
Awad
J A
JA
Mirochnitchenko
O
O
Swift
L L
LL
Burk
R F
RF
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D002251:Carbon Tetrachloride / Q000494:pharmacology; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000378:metabolism; D015232:Dinoprostone / Q000031:analogs & derivatives* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism; D015227:Lipid Peroxidation; D008099:Liver / Q000378:metabolism*; D008297:Male; D008315:Malondialdehyde / Q000032:analysis; D051379:Mice; D008822:Mice, Transgenic; D008861:Microsomes / Q000378:metabolism; D008862:Microsomes, Liver / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D010313:Partial Pressure; D010743:Phospholipids / Q000302:isolation & purification / Q000378:metabolism*; D015230:Prostaglandin D2 / Q000031:analogs & derivatives* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D010743:Phospholipids; D008315:Malondialdehyde; D000244:Adenosine Diphosphate; D015237:Dinoprost; D002251:Carbon Tetrachloride; D007501:Iron; D005979:Glutathione Peroxidase; D005978:Glutathione; D015232:Dinoprostone; D001205:Ascorbic Acid; D015230:Prostaglandin D2; D010100:Oxygen