کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1976223 1060681 2008 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Altered fibre types in gastrocnemius muscle of high wheel-running selected mice with mini-muscle phenotypes
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Altered fibre types in gastrocnemius muscle of high wheel-running selected mice with mini-muscle phenotypes
چکیده انگلیسی

Selective breeding of mice for high voluntary wheel running has favoured characteristics that facilitate sustained, aerobically supported activity, including a “mini-muscle” phenotype with markedly reduced hind limb muscle mass, increased mass-specific activities of oxidative enzymes, decreased % myosin heavy chain IIb, and, in the medial gastrocnemius, reduced twitch speed, reduced mass-specific isotonic power, and increased fatigue resistance. To evaluate whether selection has altered fibre type expression in mice with either “mini” or normal muscle phenotypes, we examined fibre types of red and white gastrocnemius. In both the medial and lateral gastrocnemius, the mini-phenotype increased activities of oxidative enzymes and decreased activities of glycolytic enzymes. In red muscle samples, the mini-phenotype markedly changed fibre types, with the % type I and type IIA fibres and the surface area of type IIA fibres increasing; in addition, mice from selected lines in general had an increased % type IIA fibres and larger type I fibres as compared with mice from control lines. White muscle samples from mini-mice showed dramatic structural alterations, with an atypical distribution of extremely small, unidentifiable fibres surrounded by larger, more oxidative fibres than normally present in white muscle. The increased proportion of oxidative fibres and these atypical small fibres together may explain the reduced mass and increased mitochondrial enzyme activities in mini-muscles. These and previous results demonstrate that extension of selective breeding beyond the time when the response of the selected trait (i.e. distance run) has levelled off can still modify the mechanistic underpinnings of this behaviour.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology - Volume 149, Issue 3, March 2008, Pages 490–500
نویسندگان
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