Dow Douglas E, Dennis Robert G, Faulkner John A
Institute of Gerontology, University of Michigan, Ann Arbor, MI 48109-2007, USA.
J Gerontol A Biol Sci Med Sci. 2005 Apr;60(4):416-24. doi: 10.1093/gerona/60.4.416.
Skeletal muscles of old rats and elderly humans lose muscle mass and maximum force. Denervation is a major cause of age-related muscle atrophy and weakness, because denervated fibers do not contract, and undergo atrophy. At any age, surgical denervation causes even more dramatic muscle atrophy and loss in force than aging does. Electrical stimulation that generates tetanic contractions of denervated muscles reduces the denervation-induced declines. We investigated whether a stimulation protocol that maintains mass and force of denervated extensor digitorum longus muscles of adult rats would also maintain these properties in denervated muscles of old rats during a 2-month period of age-induced declines in these properties. Contractile activity generated by the electrical stimulation eliminated age-related losses in muscle mass and reduced the deficit in force by 50%. These data provide support for the hypothesis that during aging, lack of contractile activity in fibers contributes to muscle atrophy and weakness.
老年大鼠和老年人的骨骼肌会出现肌肉质量和最大力量的丧失。去神经支配是与年龄相关的肌肉萎缩和无力的主要原因，因为去神经支配的纤维不再收缩，并会发生萎缩。在任何年龄段，手术去神经支配所导致的肌肉萎缩和力量丧失都比衰老更为显著。能使去神经支配的肌肉产生强直收缩的电刺激可减轻去神经支配引起的肌肉衰退。我们研究了一种能维持成年大鼠去神经支配的趾长伸肌质量和力量的刺激方案，在两个月的时间里，随着年龄增长这些特性出现衰退时，该方案是否也能维持老年大鼠去神经支配肌肉的这些特性。电刺激产生的收缩活动消除了与年龄相关的肌肉质量损失，并使力量 deficit 减少了 50%。这些数据为以下假设提供了支持：在衰老过程中，纤维中缺乏收缩活动会导致肌肉萎缩和无力。
