Possible involvement of the α1 isoform of 5′AMP-activated protein kinase in oxidative stress-stimulated glucose transport in skeletal muscle

• Published in: American journal of physiology: endocrinology and metabolism Vol. 287; no. 1; pp. E166 - E173
• Main Authors: Toyoda, Taro, Hayashi, Tatsuya, Miyamoto, Licht, Yonemitsu, Shin, Nakano, Masako, Tanaka, Satsuki, Ebihara, Ken, Masuzaki, Hiroaki, Hosoda, Kiminori, Inoue, Gen, Otaka, Akira, Sato, Kenji, Fushiki, Tohru, Nakao, Kazuwa
• Format: Journal Article
• Language: English
• Published: 01.07.2004
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.00487.2003

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 , AMPKα1 activity increased in a time- and dose-dependent manner, whereas AMPKα2 activity remained unchanged. The activation of AMPKα1 was associated with phosphorylation of AMPK Thr 172 , suggesting that an upstream kinase is involved in the activation process. H 2 O 2 -induced AMPKα1 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 AMPKα1 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 AMPKα1-mediated mechanism.