Cleveland Clinic, Pathobiology, Cleveland, OH 44195, USA.
Int J Sports Med. 2013 Aug;34(8):695-9. doi: 10.1055/s-0032-1327659. Epub 2013 Jan 16.
Aging may alter protein metabolism during periods of metabolic and physiologic challenge. The purpose of this study was to assess the effects of age on whole-body amino acid turnover in response to eccentric exercise and hyperglycemia-induced hyperinsulinemia. 16 healthy men were divided into young (N=8) and older (N=8) groups. Protein metabolism was assessed using a [1-13C]-leucine isotopic tracer approach. Measures were obtained under fasted basal conditions and during 3-h hyperglycemic clamps that were performed without (control) and 48 h after eccentric exercise. Exercise reduced leucine oxidation in the younger men (P<0.05), but not in older men. Insulin sensitivity was inversely correlated with leucine oxidation (P<0.05), and was lower in older men (P<0.05). Healthy aging is associated with an impaired capacity to adjust protein oxidation in response to eccentric exercise. The decreased efficiency of protein utilization in older men may contribute to impaired maintenance, growth, and repair of body tissues with advancing age.
衰老可能会改变代谢和生理挑战期间的蛋白质代谢。本研究旨在评估年龄对全身氨基酸周转率的影响，以响应离心运动和高血糖诱导的高胰岛素血症。16 名健康男性被分为年轻组（N=8）和老年组（N=8）。使用[1-13C]-亮氨酸同位素示踪剂方法评估蛋白质代谢。在空腹基础条件下和进行 3 小时高血糖钳夹期间（无（对照）和离心运动后 48 小时）获得测量值。运动降低了年轻男性的亮氨酸氧化（P<0.05），但对老年男性没有影响。胰岛素敏感性与亮氨酸氧化呈负相关（P<0.05），老年男性的胰岛素敏感性较低（P<0.05）。健康衰老与离心运动后蛋白质氧化的调节能力受损有关。随着年龄的增长，老年男性蛋白质利用效率的降低可能导致身体组织的维持、生长和修复受损。
