Daw C K, Starnes J W, White T P
Department of Kinesiology, University of Michigan, Ann Arbor 48109-2214.
J Appl Physiol (1985). 1988 Jun;64(6):2428-32. doi: 10.1152/jappl.1988.64.6.2428.
The purpose of this work is to study the influence of aging, training, and food restriction on skeletal muscle mass and fiber number. Male Fischer 344 rats (n = 49) at 3 mo postpartum were assigned to three groups: 1) sedentary control (confined to cage), 2) exercise trained (18 m/min, 8 degrees grade, 20 min/day, 5 days/wk), or 3) food restricted (alternate days of free access and no access to food). At 12 and 27 mo postpartum the soleus and extensor digitorum longus (EDL) muscles were excised, weighed, and fiber number was quantified after HNO3 digestion. At 27 mo the masses of soleus and EDL muscles of sedentary control rats were 83 and 70%, respectively, of 12-mo values (138 +/- 5 and 151 +/- 4 mg). At 27 mo, soleus muscle mass of trained rats was 113% of sedentary control values, whereas EDL muscle mass was unaffected by training. At 27 mo, food restriction had no effect on the mass of both muscles compared with 27-mo sedentary control values. Fiber number was not affected by training or food restriction in both muscles. Fiber number for soleus and EDL muscles of combined groups declined with age by 5.6 and 4.2%, respectively. With aging, the small loss of muscle fibers can account at most for approximately 25% of the observed skeletal muscle atrophy.
本研究的目的是探讨衰老、训练和食物限制对骨骼肌质量和纤维数量的影响。将产后3个月的雄性Fischer 344大鼠（n = 49）分为三组：1）久坐对照组（关在笼中），2）运动训练组（速度18米/分钟，坡度8度，每天20分钟，每周5天），或3）食物限制组（隔天自由进食和禁食）。在产后12个月和27个月时，切除比目鱼肌和趾长伸肌（EDL），称重，并在硝酸消化后对纤维数量进行定量分析。在27个月时，久坐对照组大鼠的比目鱼肌和EDL肌肉质量分别为12个月时的83%和70%（138±5和151±4毫克）。在27个月时，训练组大鼠的比目鱼肌质量是久坐对照组的113%，而EDL肌肉质量不受训练影响。在27个月时，与27个月的久坐对照组相比，食物限制对这两块肌肉的质量均无影响。两块肌肉的纤维数量均不受训练或食物限制的影响。合并组的比目鱼肌和EDL肌肉纤维数量随年龄增长分别下降了5.6%和4.2%。随着年龄的增长，肌肉纤维的少量损失最多可解释约25%的观察到的骨骼肌萎缩。
