Contraction-induced injury to single permeabilized muscle fibers from mdx, transgenic mdx, and control mice
Contraction-induced injury to single permeabilized muscle fibers from mdx, transgenic mdx, and control mice
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DOI：
10.1152/ajpcell.2000.279.4.c1290
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发表时间：
2000-10-01
影响因子：
5.5
通讯作者：
Faulkner, JA
中科院分区：
文献类型：
--
作者：
Lynch, GS;Rafael, JA;Faulkner, JA
缺乏肌营养不良蛋白的 mdx 小鼠的肌肉纤维更容易受到收缩引起的损伤，特别是在拉伸时。相比之下，过度表达肌营养不良蛋白的转基因 mdx (tg-mdx) 小鼠没有表现出营养不良的形态或功能迹象。透化破坏了 mdx、tg-mdx 和对照小鼠肌肉的纤维肌膜。我们测试了零假设，即在最大程度激活的单根透化纤维单次拉伸后，来自 mdx、tg-mdx 或对照小鼠的指长伸肌的纤维之间的力缺陷没有差异。纤维被 Ca2+ (pCa 4.5) 最大限度地激活，然后以 0.5 L-f/s 的速度拉伸纤维长度 (L-f) 的 10%、20% 或 30% 的应变。每次拉紧后，三组小鼠的纤维的力不足没有差异。当与 mdx、tg-mdx 和对照小鼠整个肌肉中膜完整纤维的研究进行比较时，这些结果表明，营养不良症状不是由肌原纤维内的因素引起的，而是由肌膜完整性的破坏引起的，而肌膜完整性通常提供针对收缩引起的损伤的保护。
Muscle fibers of mdx mice that lack dystrophin are more susceptible to contraction-induced injury, particularly when stretched. In contrast, transgenic mdx (tg-mdx) mice, which overexpress dystrophin, show no morphological or functional signs of dystrophy. Permeabilization disrupts the sarcolemma of fibers from muscles of mdx, tg-mdx, and control mice. We tested the null hypothesis stating that, after single stretches of maximally activated single permeabilized fibers, force deficits do not differ among fibers from extensor digitorum longus muscles of mdx, tg-mdx, or control mice. Fibers were maximally activated by Ca2+ (pCa 4.5) and then stretched through strains of 10%, 20%, or 30% of fiber length (L-f) at a velocity of 0.5 L-f/s. Immediately after each strain, the force deficits were not different for fibers from each of the three groups of mice. When collated with studies of membrane-intact fibers in whole muscles of mdx, tg-mdx, and control mice, these results indicate that dystrophic symptoms do not arise from factors within myofibrils but, rather, from disruption of the sarcolemmal integrity that normally provides protection from contraction-induced injury.