Stephens T J, Chen Z-P, Canny B J, Michell B J, Kemp B E, McConell G K
Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
Am J Physiol Endocrinol Metab. 2002 Mar;282(3):E688-94. doi: 10.1152/ajpendo.00101.2001.
The effect of prolonged moderate-intensity exercise on human skeletal muscle AMP-activated protein kinase (AMPK)alpha1 and -alpha2 activity and acetyl-CoA carboxylase (ACCbeta) and neuronal nitric oxide synthase (nNOSmu) phosphorylation was investigated. Seven active healthy individuals cycled for 30 min at a workload requiring 62.8 +/- 1.3% of peak O(2) consumption (VO(2 peak)) with muscle biopsies obtained from the vastus lateralis at rest and at 5 and 30 min of exercise. AMPKalpha1 activity was not altered by exercise; however, AMPKalpha2 activity was significantly (P < 0.05) elevated after 5 min (approximately 2-fold), and further elevated (P < 0.05) after 30 min (approximately 3-fold) of exercise. ACCbeta phosphorylation was increased (P < 0.05) after 5 min (approximately 18-fold compared with rest) and increased (P < 0.05) further after 30 min of exercise (approximately 36-fold compared with rest). Increases in AMPKalpha2 activity were significantly correlated with both increases in ACCbeta phosphorylation and reductions in muscle glycogen content. Fat oxidation tended (P = 0.058) to increase progressively during exercise. Muscle creatine phosphate was lower (P < 0.05), and muscle creatine, calculated free AMP, and free AMP-to-ATP ratio were higher (P < 0.05) at both 5 and 30 min of exercise compared with those at rest. At 30 min of exercise, the values of these metabolites were not significantly different from those at 5 min of exercise. Phosphorylation of nNOSmu was variable, and despite the mean doubling with exercise, statistically significance was not achieved (P = 0.304). Western blots indicated that AMPKapproximately 2 was associated with both nNOSmu and ACCbeta consistent with them both being substrates of AMPKalpha2 in vivo. In conclusion, AMPKalpha2 activity and ACCbeta phosphorylation increase progressively during moderate exercise at approximately 60% of VO(2 peak) in humans, with these responses more closely coupled to muscle glycogen content than muscle AMP/ATP ratio.
研究了长时间中等强度运动对人骨骼肌中AMP激活的蛋白激酶（AMPK）α1和α2活性以及乙酰辅酶A羧化酶（ACCβ）和神经元型一氧化氮合酶（nNOSμ）磷酸化的影响。7名健康活跃个体在一个需要达到峰值耗氧量（VO₂峰值）62.8±1.3%的工作量下进行30分钟的骑行运动，在运动前、运动5分钟和30分钟时从股外侧肌获取肌肉活检样本。运动未改变AMPKα1的活性；然而，AMPKα2的活性在运动5分钟后显著升高（P<0.05）（约2倍），在运动30分钟后进一步升高（P<0.05）（约3倍）。ACCβ的磷酸化在运动5分钟后增加（P<0.05）（与运动前相比约18倍），在运动30分钟后进一步增加（P<0.05）（与运动前相比约36倍）。AMPKα2活性的增加与ACCβ磷酸化的增加以及肌肉糖原含量的降低均显著相关。脂肪氧化在运动过程中呈逐渐增加趋势（P=0.058）。与运动前相比，运动5分钟和30分钟时肌肉磷酸肌酸含量降低（P<0.05），肌肉肌酸、计算得出的游离AMP以及游离AMP与ATP的比值升高（P<0.05）。在运动30分钟时，这些代谢物的值与运动5分钟时无显著差异。nNOSμ的磷酸化情况不一，尽管运动后平均增加了一倍，但未达到统计学显著性（P=0.304）。蛋白质免疫印迹表明，AMPKα2与nNOSμ和ACCβ均相关，这与它们在体内均为AMPKα2的底物相一致。总之，在人类以约60%VO₂峰值进行中等强度运动期间，AMPKα2活性和ACCβ磷酸化逐渐增加，这些反应与肌肉糖原含量的关联比与肌肉AMP/ATP比值更为紧密。
