PROTEIN METABOLISM IN HEALTHY ELDERLY ADULTS

瘦体重和骨骼肌质量随着年龄的增长而下降。 尽管如此，总体上，身体蛋白质代谢的参数 60岁到60岁之间的年轻人和老年人的情况大致相同 当数据以单位瘦质量表示时为75年。健康 老年人有能力维持蛋白质中的氮平衡 摄入量与年轻人的需要水平一致，并在 一般情况下，健康的老年受试者可以在 饮食蛋白质摄入量与年轻人相似的时尚 减少了。蛋白质周转稳定的特点是 同位素标记的氨基酸和质谱学。什么时候 校正了健康人的瘦体重和全身蛋白质周转率 老年人与年轻人的数据没有什么不同。 然而，非肌肉组织对 由于部分肌肉的存在，整个身体的蛋白质周转增加 蛋白质合成率随年龄增长而下降。这一减少 然而，肌肉蛋白质合成并不是简单的 衰老本身，因为在以下情况下，比率恢复到年轻人的值 老化的肌肉可以对抗抵抗力。此外，运动训练 改善老年人的肌肉质量和力量。与年龄相关的 生长激素分泌减少不太可能是 老年人的肌肉质量减少，因为有益的影响 抵抗力运动训练对肌肉功能的影响不大 通过补充生长激素治疗。

Lean body mass and skeletal muscle mass decline with aging. Nonetheless, on the whole, the parameters of body protein metabolism are much the same in young and elder adults between the ages of 60 and 75 years when the data are expressed per unit lean mass. Healthy elderly adults are capable of maintaining nitrogen balance at protein intakes consistent with the young adult requirement level and, in general, healthy older subjects can reestablish nitrogen balance in a fashion similar to young adults when dietary protein intake is reduced. Protein turnover can be characterized with stable isotopically labeled amino acids and mass spectrometry. When corrected for lean mass, whole body protein turnover in healthy elderly adults is no different from that measured in younger adults. Nevertheless, the proportional contribution of non-muscle tissues to whole body protein turnover is increased since the fractional muscle protein synthesis rate declines with age. This reduction in muscle protein synthesis, however, is not simply a consequence of aging per se because the rate returns to a young adult value when aging muscles work against resistance. Further, exercise training improves muscle mass and strength in older adults. The age-dependent diminution in growth hormone secretion is not likely the cause of reduced muscle mass in the elderly since the beneficial effects of resistance exercise training along on muscle function are not enhanced by supplemental growth hormone treatment.