Macpherson P C, Schork M A, Faulkner J A
Institute of Gerontology, University of Michigan, Ann Arbor 48109, USA.
Am J Physiol. 1996 Nov;271(5 Pt 1):C1438-46. doi: 10.1152/ajpcell.1996.271.5.C1438.
Susceptibility to contraction-induced injury was investigated in single permeabilized muscle fiber segments from fast extensor digitorum longus and slow soleus muscles of rats. We tested the hypotheses that, after single stretches of varying strains and under three conditions of Ca2+ activation (none, submaximum, and maximum), 1) the magnitude of the deficit in maximum isometric force is dependent on the work done to stretch the fiber, and 2) for each condition of activation and strain, fast fibers incur greater force deficits than slow fibers. When all data on force deficits were analyzed together, the best predictors of the overall force deficits for both fast and slow muscle fibers were linear regression models that introduced the simultaneous but independent effects of strain and average force (r2 = 0.52 and 0.63, respectively). Under comparable conditions, greater force deficits were produced in fast than slows fibers. Despite differences in the strain required to produce injury in fast and slow muscle fibers, for a given force deficit, the ultrastructural damage was strikingly similar.
在大鼠的快肌趾长伸肌和慢肌比目鱼肌的单个通透肌纤维节段中，研究了收缩诱导损伤的易感性。我们检验了以下假设：在不同应变的单次拉伸后，以及在三种钙离子激活条件（无、次最大和最大）下，1）最大等长力的 deficit 大小取决于拉伸纤维所做的功，2）对于每种激活和应变条件，快肌纤维比慢肌纤维产生更大的力 deficit。当对所有关于力 deficit 的数据进行综合分析时，快肌和慢肌纤维总体力 deficit 的最佳预测指标是线性回归模型，该模型引入了应变和平均力的同时但独立的影响（r2 分别为 0.52 和 0.63）。在可比条件下，快肌纤维产生的力 deficit 比慢肌纤维更大。尽管快肌和慢肌纤维产生损伤所需的应变不同，但对于给定的力 deficit，超微结构损伤惊人地相似。
