title: Possible involvement of the alpha1 isoform of 5'AMP-activated protein kinase in oxidative stress-stimulated glucose transport in skeletal muscle.
abstract: Recent studies have suggested that 5'AMP-activated protein kinase (AMPK) is activated in response to metabolic stresses, such as contraction, hypoxia, and the inhibition of oxidative phosphorylation, which leads to insulin-independent glucose transport in skeletal muscle. In the present study, we hypothesized that acute oxidative stress increases the rate of glucose transport via an AMPK-mediated mechanism. When rat epitrochlearis muscles were isolated and incubated in vitro in Krebs buffer containing the oxidative agent H(2)O(2), AMPKalpha1 activity increased in a time- and dose-dependent manner, whereas AMPKalpha2 activity remained unchanged. The activation of AMPKalpha1 was associated with phosphorylation of AMPK Thr(172), suggesting that an upstream kinase is involved in the activation process. H(2)O(2)-induced AMPKalpha1 activation was blocked in the presence of the antioxidant N-acetyl-l-cysteine (NAC), and H(2)O(2) significantly increased the ratio of oxidized glutathione to glutathione (GSSG/GSH) concentrations, a sensitive marker of oxidative stress. H(2)O(2) did not cause an increase in the conventional parameters of AMPK activation, such as AMP and AMP/ATP. H(2)O(2) increased 3-O-methyl-d-glucose transport, and this increase was partially, but significantly, blocked in the presence of NAC. Results were similar when the muscles were incubated in a superoxide-generating system using hypoxanthine and xanthine oxidase. Taken together, our data suggest that acute oxidative stress activates AMPKalpha1 in skeletal muscle via an AMP-independent mechanism and leads to an increase in the rate of glucose transport, at least in part, via an AMPKalpha1-mediated mechanism.
authors.affiliation: Dept. of Medicine and Clinical Science, Kyoto Univ. Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Toyoda
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Licht
authors.initials: L
authors.lastname: Miyamoto
authors.forename: Shin
authors.initials: S
authors.lastname: Yonemitsu
authors.forename: Masako
authors.initials: M
authors.lastname: Nakano
authors.forename: Satsuki
authors.initials: S
authors.lastname: Tanaka
authors.forename: Ken
authors.initials: K
authors.lastname: Ebihara
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Masuzaki
authors.forename: Kiminori
authors.initials: K
authors.lastname: Hosoda
authors.forename: Gen
authors.initials: G
authors.lastname: Inoue
authors.forename: Akira
authors.initials: A
authors.lastname: Otaka
authors.forename: Kenji
authors.initials: K
authors.lastname: Sato
authors.forename: Tohru
authors.initials: T
authors.lastname: Fushiki
authors.forename: Kazuwa
authors.initials: K
authors.lastname: Nakao
mesh_terms: D055372:AMP-Activated Protein Kinases; D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C568306:(3-ethoxycarbonyloxirane-2-carbonyl)leucine (3-methylbutyl) amide; D007527:Isoenzymes; D009097:Multienzyme Complexes; D006861:Hydrogen Peroxide; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D007930:Leucine; D005947:Glucose; D000111:Acetylcysteine