Brooks S V, Faulkner J A
Department of Physiology, University of Michigan, Ann Arbor 48109-0622.
Am J Physiol. 1990 Mar;258(3 Pt 1):C436-42. doi: 10.1152/ajpcell.1990.258.3.C436.
We tested the hypothesis that after the same amount of contraction-induced injury, skeletal muscles in old mice regenerate less well than muscles in young mice. Extensor digitorum longus (EDL) muscles in young and old mice were exposed to 15 min of lengthening contractions. The amount of injury was evaluated at 3, 7, 14, 28, and 60 days by measurements of maximum isometric tetanic force (Po) and number of fibers per cross section. When values 3 days after lengthening contractions were expressed as a percentage of control values, the Po (approximately 34%) and fiber number (approximately 80%) for muscles in old mice were not different from those in young mice, suggesting that muscles in old and young mice were injured to the same degree. By 28 days, injured muscles in young mice regained control values for Po and fiber number. In contrast, at 28 days, injured muscles in old mice recovered approximately 84 and approximately 87% of control values for Po and fiber number, respectively, and deficits in Po persisted at 60 days. We conclude that injured muscles regenerate less well in old mice than in young mice.
在同等程度的收缩诱导损伤后，老年小鼠的骨骼肌再生能力不如年轻小鼠的肌肉。对年轻和老年小鼠的趾长伸肌（EDL）施加15分钟的拉长收缩。在第3、7、14、28和60天，通过测量最大等长强直收缩力（Po）和每横截面积的纤维数量来评估损伤程度。当将拉长收缩后3天的值表示为对照值的百分比时，老年小鼠肌肉的Po（约34%）和纤维数量（约80%）与年轻小鼠的并无差异，这表明老年和年轻小鼠的肌肉受到的损伤程度相同。到第28天，年轻小鼠受损肌肉的Po和纤维数量恢复到对照值。相比之下，在第28天，老年小鼠受损肌肉的Po和纤维数量分别恢复到对照值的约84%和约87%，并且在第60天Po仍存在不足。我们得出结论，受损肌肉在老年小鼠中的再生能力不如在年轻小鼠中。
