Dept. of Physiology, Univ. of Melbourne, Victoria, Australia.
Am J Physiol Endocrinol Metab. 2010 Mar;298(3):E577-85. doi: 10.1152/ajpendo.00239.2009. Epub 2009 Dec 15.
Reactive oxygen species (ROS) and nitric oxide (NO) have been implicated in the regulation of skeletal muscle glucose uptake during contraction, and there is evidence that they do so via interaction with AMP-activated protein kinase (AMPK). In this study, we tested the hypothesis that ROS and NO regulate skeletal muscle glucose uptake during contraction via an AMPK-independent mechanism. Isolated extensor digitorum longus (EDL) and soleus muscles from mice that expressed a muscle-specific kinase dead AMPKalpha2 isoform (AMPK-KD) and wild-type litter mates (WT) were stimulated to contract, and glucose uptake was measured in the presence or absence of the antioxidant N-acetyl-l-cysteine (NAC) or the nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-l-arginine (l-NMMA). Contraction increased AMPKalpha2 activity in WT but not AMPK-KD EDL muscles. However, contraction increased glucose uptake in the EDL and soleus muscles of AMPK-KD and WT mice to a similar extent. In EDL muscles, NAC and l-NMMA prevented contraction-stimulated increases in oxidant levels (dichloroflourescein fluorescence) and NOS activity, respectively, and attenuated contraction-stimulated glucose uptake in both genotypes to a similar extent. In soleus muscles of AMPK-KD and WT mice, NAC prevented contraction-stimulated glucose uptake and l-NMMA had no effect. This is likely attributed to the relative lack of neuronal NOS in the soleus muscles compared with EDL muscles. Contraction increased AMPKalpha Thr(172) phosphorylation in EDL and soleus muscles of WT but not AMPK-KD mice, and this was not affected by NAC or l-NMMA treatment. In conclusion, ROS and NO are involved in regulating skeletal muscle glucose uptake during contraction via an AMPK-independent mechanism.
活性氧（ROS）和一氧化氮（NO）被认为参与了收缩过程中骨骼肌葡萄糖摄取的调节，有证据表明它们通过与 AMP 激活的蛋白激酶（AMPK）相互作用来实现这一功能。在这项研究中，我们测试了一个假设，即 ROS 和 NO 通过一种 AMPK 独立的机制来调节收缩过程中骨骼肌的葡萄糖摄取。我们从表达肌肉特异性激酶失活 AMPKα2 同工型（AMPK-KD）的小鼠和野生型同窝仔鼠（WT）中分离出伸趾长肌（EDL）和比目鱼肌，刺激它们收缩，并在存在或不存在抗氧化剂 N-乙酰-L-半胱氨酸（NAC）或一氧化氮合酶（NOS）抑制剂 N(G)-单甲基-L-精氨酸（l-NMMA）的情况下测量葡萄糖摄取。收缩增加了 WT 但不是 AMPK-KD EDL 肌肉中 AMPKα2 的活性。然而，收缩使 AMPK-KD 和 WT 小鼠的 EDL 和比目鱼肌中的葡萄糖摄取增加到相似的程度。在 EDL 肌肉中，NAC 和 l-NMMA 分别防止了收缩刺激引起的氧化剂水平（二氯荧光素荧光）和 NOS 活性的增加，并使两种基因型的收缩刺激引起的葡萄糖摄取减少到相似的程度。在 AMPK-KD 和 WT 小鼠的比目鱼肌中，NAC 阻止了收缩刺激引起的葡萄糖摄取，而 l-NMMA 没有影响。这可能归因于与 EDL 肌肉相比，比目鱼肌中神经元 NOS 的相对缺乏。收缩增加了 WT 但不是 AMPK-KD 小鼠的 EDL 和比目鱼肌中 AMPKα Thr(172)的磷酸化，而 NAC 或 l-NMMA 处理对此没有影响。总之，ROS 和 NO 通过一种 AMPK 独立的机制参与了收缩过程中骨骼肌葡萄糖摄取的调节。
