Aging does not impair the anabolic response to a protein-rich meal
Aging does not impair the anabolic response to a protein-rich meal
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DOI：
10.1093/ajcn/86.2.451
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发表时间：
2007-08-01
影响因子：
7.1
通讯作者：
Paddon-Jones, Douglas
中科院分区：
文献类型：
--
作者：
Symons, T. Brock;Schutzler, Scott E.;Paddon-Jones, Douglas
背景资料：肌肉减少症是一种使老年人衰弱的疾病，可能是由于膳食蛋白质摄入不足或无效所致。我们以前表明，自由形式的必需氨基酸急性刺激肌肉蛋白质的合成在年轻人和老年人。然而，一种实际的富含蛋白质的食物是否能刺激年轻人和老年人的肌肉合成还没有被探索。目的：我们旨在描述健康年轻人血浆氨基酸浓度的变化，并量化肌肉蛋白质的合成（41 +/- 8岁; n = 10）和老年（70 +/- 5岁; n = 10）人摄入113克（4盎司）的瘦牛肉后。设计：静脉血样本和股外侧肌活检样本在预充期间获得。（2.0 μ mol/kg）恒定输注（0.08 μ mol中心点kg（-1）中心点min（-1））L-[环-C-13（6）]苯丙氨酸。结果：老年人和老年人的混合肌肉合成率（FSR）分别比对照组增加了51%和100%，而老年人和老年人的FSR分别比对照组增加了51%和100%，（平均值+/- SE测量值：0.072 +/- 0.004%/h和0.108 +/- 0.006%/h）和年轻人（0.074 +/- 0.005%/h和0.113 +/- 0.005%/h）。两个年龄组的血浆氨基酸浓度在摄入牛肉后约100分钟达到峰值，但老年人的血浆氨基酸浓度要高得多（2185 +/- 134 nmol/mL与1403 +/- 96 nmol/mL相比; P < 0.001）。尽管血浆前体库中氨基酸的浓度不同，在摄取普通的富含蛋白质的食物后，衰老不会损害急性合成肌肉蛋白质的能力。
Background: Sarcopenia is a debilitating condition afflicting the elderly that may be facilitated by insufficient or ineffectual intake of dietary protein. We previously showed that free-form essential amino acids acutely stimulate muscle protein synthesis in both the young and the elderly. However, the ability of an actual protein-rich food to stimulate anabolism in the young and the elderly has not been explored.Objective: We aimed to characterize changes in plasma amino acid concentrations and to quantify muscle protein synthesis in healthy young (41 +/- 8 y old; n = 10) and elderly (70 +/- 5 y old; n = 10) persons after ingestion of a 113-g (4-oz) serving of lean beef.Design: Venous blood samples and vastus lateralis muscle biopsy samples were obtained during a primed (2.0 mu mol/kg) constant infusion (0.08 mu mol center dot kg(-1)center dot min(-1)) of L-[ring-C-13(6)] phenylalanine. Plasma amino acid concentrations were measured and a mixed-muscle fractional synthesis rate (FSR) was calculated during the premeal period and for 5 h after beef ingestion.Results: Mixed-muscle FSR increased by approximate to 51% in both the elderly (mean +/- SE measurements: 0.072 +/- 0.004%/h and 0.108 +/- 0.006%/h before and after the meal, respectively) and the young (0.074 +/- 0.005%/h and 0.113 +/- 0.005%/h before and after the meal, respectively) after beef ingestion (P < 0.001). Plasma amino acid concentrations peaked at approximate to 100 min after beef ingestion in both age groups but were substantially higher in the elderly (2185 +/- 134 nmol/mL compared with 1403 +/- 96 nmol/mL; P < 0.001).Conclusion: Despite differences in the concentration of amino acids in the plasma precursor pool, aging does not impair the ability to acutely synthesize muscle protein after ingestion of a common protein-rich food.