Age-related changes in ATP-producing pathways in human skeletal muscle in vivo
Age-related changes in ATP-producing pathways in human skeletal muscle in vivo
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DOI：
10.1152/japplphysiol.00566.2005
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发表时间：
2005-11-01
影响因子：
3.3
通讯作者：
Kent-Braun, JA
中科院分区：
文献类型：
--
作者：
Lanza, IR;Befroy, DE;Kent-Braun, JA
肌肉收缩所需的能量由1)通过肌酸激酶反应使磷酸肌酸(PCr)净水解、2)氧化磷酸化和3)无氧糖酵解产生的ATP提供。老年对这些途径的影响尚不清楚。本研究的目的是研究在最大自主等长收缩(MVIC)过程中，年龄是否会影响这些途径的ATP合成率。用磷磁共振波谱分析了8名年轻男性(20-35岁)和8名老年男性(65-80岁)骨骼肌中高能磷代谢物的浓度。从16-S MVIC后的聚合酶链式反应恢复来评估氧化能力。我们确定了在60-S MVIC期间每条途径对总三磷酸腺苷合成的贡献。不同年龄组的氧化能力相似。在60-S MVIC期间，年轻男性和老年男性从聚合酶水解和氧化磷酸化合成三磷酸腺苷的速率相似。在60-S收缩期间，年轻人的糖酵解通量高于老年男性(P<；0.001)。相对于总的三磷酸腺苷合成速率，老年男性比年轻男性更依赖氧化磷酸化(P=0.014)，从无氧糖酵解中获得三磷酸腺苷的比例较小(P<；0.001)。这些数据表明，尽管氧化能力没有随着年龄的增长而改变，但在高强度收缩期间，老年男性无氧糖酵解的峰值糖酵解通量和总的ATP产量较低。这是否代表了糖酵解代谢的年龄相关限制，还是偏爱于氧化的三磷酸腺苷生产，仍有待确定。
Energy for muscle contractions is supplied by ATP generated from 1) the net hydrolysis of phosphocreatine (PCr) through the creatine kinase reaction, 2) oxidative phosphorylation, and 3) anaerobic glycolysis. The effect of old age on these pathways is unclear. The purpose of this study was to examine whether age may affect ATP synthesis rates from these pathways during maximal voluntary isometric contractions (MVIC). Phosphorus magnetic resonance spectroscopy was used to assess high-energy phosphate metabolite concentrations in skeletal muscle of eight young ( 20 - 35 yr) and eight older ( 65 - 80 yr) men. Oxidative capacity was assessed from PCr recovery after a 16-s MVIC. We determined the contribution of each pathway to total ATP synthesis during a 60-s MVIC. Oxidative capacity was similar across age groups. Similar rates of ATP synthesis from PCr hydrolysis and oxidative phosphorylation were observed in young and older men during the 60-s MVIC. Glycolytic flux was higher in young than older men during the 60-s contraction ( P < 0.001). When expressed relative to the overall ATP synthesis rate, older men relied on oxidative phosphorylation more than young men ( P = 0.014) and derived a smaller proportion of ATP from anaerobic glycolysis ( P < 0.001). These data demonstrate that although oxidative capacity was unaltered with age, peak glycolytic flux and overall ATP production from anaerobic glycolysis were lower in older men during a high-intensity contraction. Whether this represents an age-related limitation in glycolytic metabolism or a preferential reliance on oxidative ATP production remains to be determined.