Effect of unilateral denervation on maximum specific force in rat diaphragm muscle fibers
Effect of unilateral denervation on maximum specific force in rat diaphragm muscle fibers
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DOI：
10.1152/jappl.2001.90.4.1196
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发表时间：
2001-04-01
影响因子：
3.3
通讯作者：
Sieck, GC
中科院分区：
文献类型：
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作者：
Geiger, PC;Cody, MJ;Sieck, GC
我们假设1)去神经支配（DNV）的影响在表达快速肌球蛋白重链（MHC）亚型的纤维中更为明显；2)DNV对最大比力的影响反映了每半个肌节中MHC含量或平行交叉桥数量的减少。在pCa （-log Ca2+浓度）为4.0时，对单个Triton x -100渗透纤维进行了研究。通过SDS-PAGE凝胶的密度分析和与已知MHC浓度的标准曲线比较，确定每半个肌节的MHC含量。DNV 2周后，表达MHC2x的纤维的最大比力下降了约40% （MHC2x没有表达），而表达MHC2A和MHCslow的纤维的最大比力仅下降了约20%。DNV还降低了表达MHC2x的纤维中MHC的含量，而对表达MHC2A和MHCslow的纤维没有影响。当对每半个肌节的MHC含量进行归一化时，与对照纤维相比，表达MHC2x和MHC2A的DNV纤维产生的力降低了。这些结果表明，每个过桥的力也受到DNV的影响。
We hypothesize that 1) the effect of denervation (DNV) is more pronounced in fibers expressing fast myosin heavy chain (MHC) isoforms and 2) the effect of DNV on maximum specific force reflects a reduction in MHC content per half sarcomere or the number of cross bridges in parallel. Studies were performed on single Triton X-100-permeabilized fibers activated at a pCa (-log Ca2+ concentration) of 4.0. MHC content per half sarcomere was determined by densitometric analysis of SDS-PAGE gels and comparison to a standard curve of known MHC concentrations. After 2 of wk DNV, the maximum specific force of fibers expressing MHC2x was reduced by similar to 40% (MHC2x expression was absent), whereas the maximum specific force of fibers expressing MHC2A and MHCslow decreased by only similar to 20%. DNV also reduced the MHC content in fibers expressing MHC2x with no effect on fibers expressing MHC2A and MHCslow. When normalized for MHC content per half sarcomere, force generated by DNV fibers expressing MHC2x and MHC2A was decreased compared with control fibers. These results suggest the force per cross bridge is also affected by DNV.