Sandström Marie E, Zhang Shi-Jin, Bruton Joseph, Silva José P, Reid Michael B, Westerblad Håkan, Katz Abram
Department of Physiology and Pharmacology, Karolinska Institutet, 171 77 Stockholm, Sweden.
J Physiol. 2006 Aug 15;575(Pt 1):251-62. doi: 10.1113/jphysiol.2006.110601. Epub 2006 Jun 15.
Exercise increases glucose transport into skeletal muscle via a pathway that is poorly understood. We investigated the role of endogenously produced reactive oxygen species (ROS) in contraction-mediated glucose transport. Repeated contractions increased 2-deoxyglucose (2-DG) uptake roughly threefold in isolated, mouse extensor digitorum longus (fast-twitch) muscle. N-Acetylcysteine (NAC), a non-specific antioxidant, inhibited contraction-mediated 2-DG uptake by approximately 50% (P < 0.05 versus control values), but did not significantly affect basal 2-DG uptake or the uptake induced by insulin, hypoxia or 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR, which mimics AMP-mediated activation of AMP-activated protein kinase, AMPK). Ebselen, a glutathione peroxidase mimetic, also inhibited contraction-mediated 2-DG uptake (by almost 60%, P < 0.001 versus control values). Muscles from mice overexpressing Mn2+-dependent superoxide dismutase, which catalyses H2O2 production from superoxide anions, exhibited a approximately 25% higher rate of contraction-mediated 2-DG uptake versus muscles from wild-type control mice (P < 0.05). Exogenous H2O2 induced oxidative stress, as judged by an increase in the [GSSG]/[GSH + GSSG] (reduced glutathione + oxidized glutathione) ratio to 2.5 times control values, and this increase was substantially blocked by NAC. Similarly, NAC significantly attenuated contraction-mediated oxidative stress as judged by measurements of glutathione status and the intracellular ROS level with the fluorescent indicator 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein (P < 0.05). Finally, contraction increased AMPK activity and phosphorylation approximately 10-fold, and NAC blocked approximately 50% of these changes. These data indicate that endogenously produced ROS, possibly H2O2 or its derivatives, play an important role in contraction-mediated activation of glucose transport in fast-twitch muscle.
运动通过一条尚不清楚的途径增加葡萄糖向骨骼肌的转运。我们研究了内源性产生的活性氧（ROS）在收缩介导的葡萄糖转运中的作用。重复收缩使分离的小鼠趾长伸肌（快肌）中的2-脱氧葡萄糖（2-DG）摄取量增加了约三倍。非特异性抗氧化剂N-乙酰半胱氨酸（NAC）抑制收缩介导的2-DG摄取约50%（与对照值相比，P<0.05），但对基础2-DG摄取或胰岛素、缺氧或5-氨基咪唑-4-甲酰胺-1-β-D-呋喃核糖苷（AICAR，模拟AMP介导的AMP激活蛋白激酶（AMPK）激活）诱导的摄取没有显著影响。谷胱甘肽过氧化物酶模拟物依布硒仑也抑制收缩介导的2-DG摄取（与对照值相比，降低近60%，P<0.001）。与野生型对照小鼠的肌肉相比，过表达催化超氧阴离子产生H2O2的锰依赖性超氧化物歧化酶的小鼠肌肉，其收缩介导的2-DG摄取速率高约25%（P<0.05）。外源性H2O2诱导氧化应激，根据[GSSG]/[GSH + GSSG]（还原型谷胱甘肽+氧化型谷胱甘肽）比值增加至对照值的2.5倍判断，NAC可显著阻断这种增加。同样，根据谷胱甘肽状态测量以及使用荧光指示剂5-（和-6）-氯甲基-2'，7'-二氯二氢荧光素测量细胞内ROS水平判断，NAC显著减轻收缩介导的氧化应激（P<0.05）。最后，收缩使AMPK活性和磷酸化增加约10倍，NAC阻断了这些变化的约50%。这些数据表明，内源性产生的ROS，可能是H2O2或其衍生物，在快肌收缩介导的葡萄糖转运激活中起重要作用。
