Klitgaard H, Zhou M, Schiaffino S, Betto R, Salviati G, Saltin B
August Krogh Institute, University of Copenhagen, Denmark.
Acta Physiol Scand. 1990 Sep;140(1):55-62. doi: 10.1111/j.1748-1716.1990.tb08975.x.
The myosin heavy chain composition of single fibres (n = 1088) was analysed with an electrophoretic technique in biopsy material from m. vastus lateralis (n = 5) and m. biceps brachii (n = 4) of young (23-31 years old) and elderly men (68-70 years old). In m. vastus lateralis, elderly subjects had a higher proportion of fibres showing a coexistence of myosin heavy chain types I and IIa (20 +/- 3% vs 8 +/- 1%, P less than 0.05) and of myosin heavy chain types IIa and IIb (33 +/- 2% vs 12 +/- 4%, P less than 0.05). In contrast, the young subjects had a higher proportion of fibres containing only myosin heavy chain type I (50 +/- 5% vs 33 +/- %, P less than 0.05) and type IIa (26 +/- 3% vs 12 +/- 2%, P less than 0.05). A similar pattern of myosin heavy chain expression was found in single fibres from m. biceps brachii, with the exception that the elderly subjects had a lower proportion of fibres with coexistence of types IIa and IIb (23 +/- 1% vs 34 +/- 2%, P less than 0.05) and a higher proportion of fibres containing only myosin heavy chain type IIa (25 +/- 5% vs 12 +/- 2%, P less than 0.05). Three fibres from m. biceps brachii contained all three isoforms. These results indicate that coexistence of myosin heavy chain isoforms in single fibres is present in skeletal muscles of young adults, and that there is an increased occurrence of this phenomenon with ageing.(ABSTRACT TRUNCATED AT 250 WORDS)
采用电泳技术对来自青年(23 - 31岁)和老年男性(68 - 70岁)的股外侧肌(n = 5)和肱二头肌(n = 4)活检材料中的单根肌纤维(n = 1088)的肌球蛋白重链组成进行了分析。在股外侧肌中,老年受试者中显示肌球蛋白重链I型和IIa型共存的纤维比例更高(20±3%对8±1%,P<0.05),以及肌球蛋白重链IIa型和IIb型共存的纤维比例更高(33±2%对12±4%,P<0.05)。相反,青年受试者中仅含肌球蛋白重链I型(50±5%对33±%,P<0.05)和IIa型(26±3%对12±2%,P<0.05)的纤维比例更高。在肱二头肌的单根肌纤维中发现了类似的肌球蛋白重链表达模式,不同的是老年受试者中IIa型和IIb型共存的纤维比例较低(23±1%对34±2%,P<0.05),而仅含肌球蛋白重链IIa型的纤维比例较高(25±5%对12±2%,P<0.05)。肱二头肌的三根纤维包含所有三种异构体。这些结果表明,单根肌纤维中肌球蛋白重链异构体的共存存在于年轻成年人的骨骼肌中,并且随着年龄增长这种现象的发生率增加。(摘要截短于250字)