Composition and size of type I, IIA, IID/X, and IIB fibers and citrate synthase activity of rat muscle
Composition and size of type I, IIA, IID/X, and IIB fibers and citrate synthase activity of rat muscle
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DOI：
10.1152/jappl.1996.80.1.261
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发表时间：
1996-01-01
影响因子：
3.3
通讯作者：
Duan, CP
中科院分区：
文献类型：
--
作者：
Delp, MD;Duan, CP
最近在大鼠肌肉中发现了一群含有肌球蛋白重链异构体IId（或2x）的肌纤维。本研究的目的是通过组织化学方法测定由IID/X型纤维以及I、IIA和IIB型纤维组成的肌纤维的相对数量和大小，以估计大鼠肌肉中不同类型纤维的绝对质量。此外，测定肌肉柠檬酸合成酶活性，以确定纤维成分与肌肉氧化能力之间的关系。取3只成年雄性（4.5-5月龄）Sprague-Dawley大鼠面部、颈部、肩部、手臂、躯干、臀部、大腿和腿部的76块肌肉或肌肉部位，称重后冷冻进行组织化学和生化分析。数据表明，IIB型纤维占总肌肉质量的71%，IID/X型纤维占18%，IIA型纤维占5%，I型纤维占6%。IIB型纤维的平均横截面积为5078 +/- 175 μ m(2)， IID/X型纤维的平均横截面积为3078 +/- 105 μ m(2)， IIA型纤维的平均横截面积为2045 +/- 80 μ m(2)， I型纤维的平均横截面积为1898 +/- 90 μ m(2)。肌肉线粒体含量指标柠檬酸合成酶活性与IIA型纤维群体关系最为密切，其等级为> I > IID/X > IIB。nadh -四氮唑还原酶染色强度也证实了这一顺序。这些数据表明，IID/X型纤维占成年大鼠肌肉质量的很大一部分，在纤维大小和氧化电位方面介于IIA和IIB型纤维之间。
A population of muscle fibers containing a myosin heavy-chain isoform IId (or 2x) has recently been identified in rat muscle. The purpose of this study was to histochemically determine the relative population and size of muscle fibers composed of type IID/X fibers as well as type I, IIA, and IIB fibers to estimate the absolute mass of the different types of fibers in rat muscle. In addition, muscle citrate synthase activity was measured to determine the relationship between fiber composition and muscle oxidative capacity. Seventy-six muscles or muscle parts from the face, neck, shoulder, arm, trunk, hip, thigh, and leg of three adult (4.5-5 mo of age) male Sprague-Dawley rats were removed, weighed, and frozen for histochemical and biochemical analyses. The data demonstrated that type IIB fibers make up 71% of the total muscle mass, type IID/X fibers 18%, type IIA fibers 5%, and type I fibers 6%. The mean cross-sectional area across all muscles was 5,078 +/- 175 mu m(2) for type IIB fibers, 3,078 +/- 105 mu m(2) for type IID/X fibers, 2,045 +/- 80 mu m(2) for type IIA fibers, and 1,898 +/- 90 mu m(2) for type I fibers. Citrate synthase activity, an indicator of muscle mitochondrial content, was most closely related to the population of type IIA fibers and was in the rank order of type IIA > I > IID/X > IIB. NADH-tetrazolium reductase staining intensity also confirmed this order. These data demonstrate that type IID/X fibers make up a significant portion of the adult rat muscle mass and are intermediate to type IIA and IIB fibers in regard to fiber size and oxidative potential.