title: Oxidative stress-induced activation of microsomal glutathione S-transferase in isolated rat liver.
abstract: The activation of microsomal glutathione (GSH) S-transferase in isolated rat liver by oxidative stress was investigated using both ischemia/reperfusion and perfusion with hydrogen peroxide. When the isolated liver was reperfused for 30 min and 60 min after 90 min ischemia, microsomal GSH S-transferase activity, but not cytosolic transferase activity, was increased 1.2-fold and 1.3-fold, respectively. In addition, microsomal GSH peroxidase activity was also significantly increased after 60 min reperfusion following ischemia. The increase in microsomal GSH S-transferase activity by ischemia/reperfusion was reversed by dithiothreitol. When N-ethylmaleimide, which activates microsomal GSH S-transferase by covalent binding to the cysteine residue of the enzyme, was incubated with microsomes, transferase activity was increased to 526% in control microsomes and to 399% in liver that underwent ischemia/reperfusion liver. These data indicate that microsomal GSH S-transferase is activated by ischemia/reperfusion of the liver by means of disulfide bond formation. When rats were pretreated with a catalase inhibitor 3-amino-1,2,4-triazole for 6 weeks, microsomal GSH S-transferase activity was increased 1.4-fold by ischemia/reperfusion, corresponding to a 1.8-fold increase as compared to the non-perfused liver of untreated rats. Perfusion of the isolated liver with hydrogen peroxide (1 mM, 15 min) also caused a significant increase in microsomal GSH S-transferase activity with a concomitant decrease in GSH content, confirming that liver microsomal GSH S-transferase in rats was activated in vivo by oxidative stress.
authors.affiliation: Laboratory of Physiology and Pharmacology, School of Health Sciences, University of the Ryukyus, Okinawa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Aniya
authors.forename: A
authors.initials: A
authors.lastname: Naito
mesh_terms: D000818:Animals; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005033:Ethylmaleimide / Q000494:pharmacology; D005609:Free Radicals; D005982:Glutathione Transferase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007511:Ischemia / Q000378:metabolism; D008099:Liver / Q000098:blood supply / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010084:Oxidation-Reduction; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological / Q000378:metabolism
chemical_list: D005609:Free Radicals; D006861:Hydrogen Peroxide; D005982:Glutathione Transferase; D005033:Ethylmaleimide; D004229:Dithiothreitol