Effects of aging on in vivo synthesis of skeletal muscle myosin heavy-chain and sarcoplasmic protein in humans
Effects of aging on in vivo synthesis of skeletal muscle myosin heavy-chain and sarcoplasmic protein in humans
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DOI：
10.1152/ajpendo.1997.273.4.e790
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发表时间：
1997-10-01
影响因子：
5.1
通讯作者：
Nair, KS
中科院分区：
文献类型：
--
作者：
Balagopal, P;Rooyackers, OE;Nair, KS
肌肉质量和收缩功能的下降是老年肌肉减少症的显著特征。由于肌球蛋白重链是一种重要的收缩蛋白，因此推测该蛋白的合成在肌肉减少症中减少。肌球蛋白重链的合成率与混合肌肉和肌浆蛋白的合成率同时测定，这些蛋白质是从24名受试者（年龄：20至92岁）在预充的L-[1-C-13]亮氨酸连续输注期间采集的系列穿刺活检样品中纯化的[C-13]亮氨酸的增量。混合肌蛋白质合成率（P < 0.01）和整体蛋白质合成率（P < 0.01）从青年到中年呈下降趋势，但随年龄增长变化不明显。肌球蛋白重链合成率也随年龄增长而下降（P < 0.01），从青年到中年再到老年呈进行性下降。然而，肌浆蛋白的合成并没有随着年龄的增长而下降。肌球蛋白重链合成率与男性和女性的肌力（P < 0.05）、循环胰岛素样生长因子I（P < 0.01）和硫酸脱氢表雄酮（P < 0.05）以及男性的游离睾酮水平（P < 0.01）相关。肌球蛋白重链合成速率的下降意味着重塑这种重要的肌肉收缩蛋白的能力下降，并可能导致老年人肌肉质量和收缩功能下降。
A decline in muscle mass and contractile function are prominent features of the sarcopenia of old age. Because myosin heavy chain is an important contractile protein, it was hypothesized that synthesis of this protein decreases in sarcopenia. The fractional synthesis rate of myosin heavy chain was measured simultaneously with rates of mixed muscle and sarcoplasmic proteins from the increment of [C-13]leucine in these proteins purified from serial needle biopsy samples taken from 24 subjects (age: from 20 to 92 yr) during a primed continuous infusion of L-[1-C-13]leucine. A decline in synthesis rate of mixed muscle protein (P < 0.01) and whole body protein (P < 0.01) was observed from young to middle age with no further change with advancing age. An age-related decline of myosin heavy-chain synthesis rate was also observed (P < 0.01), with progressive decline occurring from young, through middle, to old age. However, sarcoplasmic protein synthesis did not decline with age. Myosin heavy-chain synthesis rate was correlated with measures of muscle strength (P < 0.05), circulating insulin-like growth factor I (P < 0.01), and dehydroepiandrosterone sulfate (P < 0.05) in men and women and free testosterone levels in men (P < 0.01). A decline in the synthesis rate of myosin heavy chain implies a decreased ability to remodel this important muscle contractile protein and likely contributes to the declining muscle mass and contractile function in the elderly.