Stelzer Julian E, Widrick Jeffrey J
Department of Exercise and Sport Science, Oregon State University, Corvallis, OR 97331, USA.
J Appl Physiol (1985). 2003 Dec;95(6):2425-33. doi: 10.1152/japplphysiol.01091.2002. Epub 2003 Aug 29.
Cross-sectional area (CSA), peak Ca2+-activated force (Po), fiber specific force (Po/CSA), and unloaded shortening velocity (Vo) were measured in slow-twitch [containing type I myosin heavy chain (MHC)] and fast-twitch (containing type II MHC) chemically skinned soleus muscle fiber segments obtained from three strains of weight-bearing and 7-day hindlimb-suspended (HS) mice. HS reduced soleus slow MHC content (from approximately 50 to approximately 33%) in CBA/J and ICR strains without affecting slow MHC content in C57BL/6 mice ( approximately 20% of total MHC). Two-way ANOVA revealed HS-induced reductions in CSA, Po, and Po/CSA of slow and fast fibers from all strains. Fiber Vo was elevated post-HS, but not consistently across strains. No MHC x HS treatment interactions were observed for any variable for C57BL/6 and CBA/J mice, and the two significant interactions found for the ICR strain (CSA, Po) appeared related to inherent pre-HS differences in slow vs. fast fiber CSA. In the mouse HS models studied here, fiber atrophy and contractile dysfunction were partially dependent on animal strain and generally independent of fiber MHC isoform content.
在从三种负重和7天悬吊后肢（HS）小鼠品系获得的慢肌纤维[含I型肌球蛋白重链（MHC）]和快肌纤维（含II型MHC）化学去表皮比目鱼肌纤维节段中，测量了横截面积（CSA）、峰值Ca2+激活力（Po）、纤维比力（Po/CSA）和无负荷缩短速度（Vo）。HS降低了CBA/J和ICR品系比目鱼肌慢MHC含量（从约50%降至约33%），但不影响C57BL/6小鼠的慢MHC含量（占总MHC的约20%）。双向方差分析显示，HS导致所有品系的慢肌纤维和快肌纤维的CSA、Po和Po/CSA降低。HS后纤维Vo升高，但各品系间不一致。对于C57BL/6和CBA/J小鼠，未观察到任何变量的MHC×HS处理交互作用，而在ICR品系中发现的两个显著交互作用（CSA、Po）似乎与慢肌纤维和快肌纤维CSA的HS前固有差异有关。在此研究的小鼠HS模型中，纤维萎缩和收缩功能障碍部分取决于动物品系，且通常与纤维MHC同工型含量无关。
