Toth M J, Arciero P J, Gardner A W, Calles-Escandon J, Poehlman E T
Division of Gerontology, Department of Medicine, University of Maryland, Gerontology Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, MD 21201, USA.
J Appl Physiol (1985). 1996 Feb;80(2):506-11. doi: 10.1152/jappl.1996.80.2.506.
Alterations in the mobilization and oxidation of fat may partially account for age-related alterations in body composition. To investigate age-related alterations in fat metabolism, we compared basal rate of appearance of free fatty acids (FFAapp) and total body fat oxidation as measured by infusions of [14C] palmitate and indirect calorimetry, respectively, in 18 younger (23 +/- 1 yr) and 30 older (69 +/- 1 yr) men. We also examined whether age-related differences in body composition, body fat distribution, peak oxygen consumption, dietary intake, and/or fasting insulin levels may explain age-related variation in FFAapp and total body fat oxidation. The FFAapp showed a tendency to be higher in older compared with younger men (1,134 +/- 184 vs. 680 +/- 105 mu mol/min; P = 0.07), whereas total body fat oxidation was similar between groups (257 +/- 25 vs. 222 +/- 9 mu mol/min). The estimated rate of nonoxidative disposal of free fatty acids showed a tendency to be higher in the older (913 +/- 182 mu mol/min) than in younger men (423 +/- 103 mu mol/min; P = 0.06). Fat-free mass was the most significant predictor of FFAapp in younger (r = 0.63; P < 0.01) and older (r = 0.41; P < 0.05) men. These results suggest that older men recruit fatty acids from adipose tissue stores in excess of the energy needs of respiring tissue. However, variation in FFAapp between the age groups could not be explained by differences in body habitus or fasting insulin levels.
脂肪动员和氧化的改变可能部分解释了与年龄相关的身体成分变化。为了研究与年龄相关的脂肪代谢变化，我们分别通过输注[14C]棕榈酸酯和间接量热法，比较了18名年轻男性（23±1岁）和30名老年男性（69±1岁）的游离脂肪酸基础出现率（FFAapp）和全身脂肪氧化情况。我们还研究了与年龄相关的身体成分、体脂分布、峰值耗氧量、饮食摄入量和/或空腹胰岛素水平差异是否可以解释FFAapp和全身脂肪氧化的年龄相关变化。与年轻男性相比，老年男性的FFAapp有升高趋势（1134±184对680±105μmol/min；P = 0.07），而两组间的全身脂肪氧化相似（257±25对222±9μmol/min）。游离脂肪酸的非氧化处理估计速率在老年男性中（913±182μmol/min）有高于年轻男性的趋势（423±103μmol/min；P = 0.06）。无脂肪量是年轻男性（r = 0.63；P < 0.01）和老年男性（r = 0.41；P < 0.05）中FFAapp的最显著预测因素。这些结果表明，老年男性从脂肪组织储存中募集的脂肪酸超过了呼吸组织的能量需求。然而，年龄组之间FFAapp的差异不能通过身体形态或空腹胰岛素水平的差异来解释。
