Role of glutathione and glutathione peroxidase in human platelet arachidonic acid metabolism.
Selective removal of intracellular glutathione (GSH) and inhibition of the GSH-dependent peroxidase (GSH-Px) by 1-chloro-2,4-dinitrobenzene (CDNB) was used to evaluate the role of GSH and GSH-Px in arachidonic acid (AA) metabolism in human platelets. Although total conversion of AA through the lipoxygenase pathway is lowered by GSH depletion, significant 12-HETE formation was observed suggesting that GSH and GSH-Px are not required for the generation of 12-HETE in human platelets. Prolonged treatment of platelets with CDNB (2 h) completely destroyed GSH-Px activity creating a model in which the effects of GSH alone could be determined. Platelet homogenates replenished with GSH, but lacking GSH-Px activity converted significantly higher amounts of AA to 12-HPETE and 12-HETE than control. Platelet cytosolic metabolism of 15-HPETE to 15-HETE decreased after CDNB, while the membrane metabolism remained similar to control due to high GSH-independent peroxidase activity associated with the membranes. These results indicate that GSH and GSH-Px function to enhance lipoxygenase activity, rather than catalyse the reduction of 12-HPETE to 12-HETE.
Hill
T D
TD
Cancer Research Center of Hawaii, University of Hawaii, Honolulu 96813.
White
J G
JG
Rao
G H
GH
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood*; D001792:Blood Platelets / Q000201:enzymology / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004137:Dinitrochlorobenzene / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000097:blood*; D005979:Glutathione Peroxidase / Q000037:antagonists & inhibitors / Q000097:blood*; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis / Q000097:blood; D015289:Leukotrienes / Q000096:biosynthesis / Q000097:blood; D008084:Lipoxygenase / Q000097:blood; D014662:Vasoconstrictor Agents / Q000096:biosynthesis / Q000097:blood
D001095:Arachidonic Acids; D004137:Dinitrochlorobenzene; D006893:Hydroxyeicosatetraenoic Acids; D015289:Leukotrienes; D014662:Vasoconstrictor Agents; D016718:Arachidonic Acid; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C021201:12-HPETE; D005979:Glutathione Peroxidase; D008084:Lipoxygenase; D005978:Glutathione