Dietary Protein Digestion and Absorption Rates and the Subsequent Postprandial Muscle Protein Synthetic Response Do Not Differ between Young and Elderly Men
Dietary Protein Digestion and Absorption Rates and the Subsequent Postprandial Muscle Protein Synthetic Response Do Not Differ between Young and Elderly Men
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DOI：
10.3945/jn.109.109173
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发表时间：
2009-09-01
影响因子：
4.2
通讯作者：
van Loon, Luc J. C.
中科院分区：
文献类型：
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作者：
Koopman, Rene;Walrand, Stephane;van Loon, Luc J. C.
饮食蛋白质的消化和/或吸收受损会降低餐后血浆氨基酸的利用率，因此可能会降低老年人餐后肌肉蛋白质的合成反应。我们的目的是比较年轻男性和老年男性体内饮食蛋白质的消化和吸收以及随后的餐后肌肉蛋白合成反应。10名老年(+/-1岁)和10名年轻(23+/-1岁)健康男性摄入了一剂35g的专门生产的胶束酪蛋白(CAS)，这种蛋白本质上是L-[1-C-13]标记的。此外，预先连续输注L-[环-H-2(5)]苯丙氨酸、L-[1-C-13]亮氨酸和L-[环-H-2(2)]酪氨酸，并采集血液和肌肉组织样本，以评估循环中膳食蛋白质衍生的苯丙氨酸的出现率以及随后的餐后6小时内肌肉蛋白质合成的比率。蛋白质摄入导致外源性苯丙氨酸在年轻和老年男性中的出现迅速增加。外源性苯丙氨酸总出现率(曲线下面积)青年组为39+/-3亩·6h·kg(-1)，老年组为38+/-2亩·6h·kg(-1)(P=0.73)。相应地，年轻志愿者(72+/-2%)和老年志愿者(73+/-1%)内脏氨基酸提取量无差异(P=0.74)。根据口服示踪剂计算，青年男性和老年男性的肌肉蛋白质合成率分别为0.063+/-0.006和0.054+/-0.004%/h，组间差异无统计学意义(P=0.27)。我们的结论是，在健康的老年男性中，摄入大量完整CAS后的蛋白质消化和吸收动力学以及随后的肌肉蛋白质合成反应没有实质性的损害。J.Nutr.139：1707-1713,2009。
Impaired digestion and/or absorption of dietary protein lowers postprandial plasma amino acid availability and, as such, could reduce the postprandial muscle protein synthetic response in the elderly. We aimed to compare in vivo dietary protein digestion and absorption and the subsequent postprandial muscle protein synthetic response between young and elderly men. Ten elderly (64 +/- 1 y) and 10 young (23 +/- 1 y) healthy males consumed a single bolus of 35 g specifically produced, intrinsically L-[1-C-13] phenylalanine-labeled micellar casein (CAS) protein. Furthermore, primed continuous infusions with L-[ring-H-2(5)]phenylalanine, L-[1-C-13] leucine, and L-[ring-H-2(2)]tyrosine were applied and blood and muscle tissue samples were collected to assess the appearance rate of dietary protein-derived phenylalanine in the circulation and the subsequent muscle protein fractional synthetic rate over a 6-h postprandial period. Protein ingestion resulted in a rapid increase in exogenous phenylalanine appearance in both the young and elderly men. Total exogenous phenylalanine appearance rates (expressed as area under the curve) were 39 +/- 3 mu mol.6 h.kg(-1) in the young men and 38 +/- 2 mu mol.6 h.kg(-1) in the elderly men (P = 0.73). In accordance, splanchnic amino acid extraction did not differ between young (72 +/- 2%) and elderly (73 +/- 1%) volunteers (P = 0.74). Muscle protein synthesis rates, calculated from the oral tracer, were 0.063 +/- 0.006 and 0.054 +/- 0.004%/h in the young and elderly men, respectively, and did not differ between groups (P = 0.27). We conclude that protein digestion and absorption kinetics and the subsequent muscle protein synthetic response following the ingestion of a large bolus of intact CAS are not substantially impaired in healthy, elderly men. J. Nutr. 139: 1707-1713, 2009.