Holloszy J O, Chen M, Cartee G D, Young J C
Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110.
Mech Ageing Dev. 1991 Oct;60(2):199-213. doi: 10.1016/0047-6374(91)90131-i.
This study was undertaken to reevaluate the effects of ageing on skeletal muscle mass and on mitochondrial and glycolytic enzyme levels in the different types of skeletal muscle in rats. It was found that some muscles atrophy with ageing, while others do not, in male rats. Atrophy appears to occur in weight-bearing muscles, and is most marked in those with a high proportion of type IIb fibers. The muscles that did not atrophy are non-weight-bearing, and include the epitrochlearis (predominantly type IIb fibers) and the adductor longus (predominantly type I fibers). The average cross-sectional area of muscle fibers in the plantaris muscles of 28-30-month-old rats was approximately 30% smaller than that of 9-10-month-old animals, providing evidence that the approximately 30% lower weight of the plantaris in the old group was entirely due to fiber atrophy. The proportion of type IIa fibers was decreased and the proportion of type I fibers was increased in the plantaris of the old rats. The respiratory capacity of the soleus muscle (predominantly type I fibers), and the glycolytic capacity of the superficial, white (type IIb) and deep, red (predominantly type IIa) portions of the vastus lateralis, were reduced in the old rats. Our results provide evidence that ageing has differential effects on the three types of skeletal muscle fiber, and on weight-bearing and non-weight-bearing muscles, in the rat.
本研究旨在重新评估衰老对大鼠不同类型骨骼肌的肌肉质量、线粒体及糖酵解酶水平的影响。研究发现，在雄性大鼠中，一些肌肉会随着衰老而萎缩，而另一些则不会。萎缩似乎发生在负重肌肉中，在那些IIb型纤维比例高的肌肉中最为明显。未发生萎缩的肌肉为非负重肌肉，包括肱三头肌（主要为IIb型纤维）和长收肌（主要为I型纤维）。28 - 30月龄大鼠的跖肌中肌纤维的平均横截面积比9 - 10月龄动物的约小30%，这证明老年组跖肌重量约低30%完全是由于纤维萎缩所致。老年大鼠跖肌中IIa型纤维比例降低，I型纤维比例增加。老年大鼠比目鱼肌（主要为I型纤维）的呼吸能力以及股外侧肌浅部白色（IIb型）和深部红色（主要为IIa型）部分的糖酵解能力均降低。我们的结果证明，衰老对大鼠的三种骨骼肌纤维类型以及负重和非负重肌肉有不同的影响。
