Benedek C, Berclaz P Y, Jéquier E, Schutz Y
Faculty of Medecine, Institut of Physiology, University of Lausanne, Switzerland.
Am J Physiol. 1995 Jun;268(6 Pt 1):E1083-8. doi: 10.1152/ajpendo.1995.268.6.E1083.
Body composition, resting energy expenditure (REE), and whole body protein metabolism were studied in 26 young and 28 elderly Gambian men matched for body mass index during the dry season in a rural village in The Gambia. REE was measured by indirect calorimetry (hood system) in the fasting state and after five successive meals. Rates of whole body nitrogen flux, protein synthesis, and protein breakdown were determined in the fed state from the level of isotopic enrichment of urinary ammonia over a period of 12 h after a single oral dose of [15N]glycine. Expressed in absolute value, REE was significantly lower in the elderly compared with the young group (3.21 +/- 0.07 vs. 4.04 +/- 0.07 kJ/min, P < 0.001) and when adjusted to body weight (3.29 +/- 0.05 vs. 3.96 +/- 0.05 kJ/min, P < 0.0001) and fat-free mass (FFM; 3.38 +/- 0.01 vs. 3.87 +/- 0.01 kJ/min, P < 0.0001). The rate of protein synthesis averaged 207 +/- 13 g protein/day in the elderly and 230 +/- 13 g protein/day in the young group, whereas protein breakdown averaged 184 +/- 13 g protein/day in the elderly and 203 +/- 13 g protein/day in the young group (nonsignificant). When values were adjusted for body weight or FFM, they did not reveal any difference between the two groups. It is concluded that the reduced REE adjusted for body composition observed in elderly Gambian men is not explained by a decrease in protein turnover.
在冈比亚一个乡村的旱季，对26名年轻和28名老年冈比亚男性进行了身体成分、静息能量消耗（REE）和全身蛋白质代谢的研究，这些男性的体重指数相匹配。通过间接测热法（面罩系统）在禁食状态和连续五餐后测量REE。在单次口服[15N]甘氨酸后12小时内，根据尿氨的同位素富集水平，在进食状态下测定全身氮通量、蛋白质合成和蛋白质分解速率。以绝对值表示，老年组的REE显著低于年轻组（3.21±0.07 vs. 4.04±0.07 kJ/分钟，P<0.001），在根据体重（3.29±0.05 vs. 3.96±0.05 kJ/分钟，P<0.0001）和去脂体重（FFM；3.38±0.01 vs. 3.87±0.01 kJ/分钟，P<0.0001）调整后也是如此。老年组蛋白质合成速率平均为207±13克蛋白质/天，年轻组为230±13克蛋白质/天，而老年组蛋白质分解平均为184±13克蛋白质/天，年轻组为203±13克蛋白质/天（无显著差异）。当根据体重或FFM调整这些值时，两组之间没有显示出任何差异。得出的结论是，在老年冈比亚男性中观察到的根据身体成分调整后的REE降低，不能用蛋白质周转率的降低来解释。
