Musacchia X J, Steffen J M, Fell R D, Dombrowski M J
Dept. Physiology, University of Louisville, KY 40292, USA.
Physiologist. 1988;31(1 Suppl):S28-9.
This work is a continuation of efforts to assess responses of rat skeletal muscle to weightlessness and earthside laboratory experiments with unloading of hind limbs. The soleus is a slow twitch, load bearing (antigravity) muscle. Both exposure to weightlessness (W) and to the hypokinesia/hypodynamia of whole body suspension (WBS) results in soleus atrophy. Cross sectional areas of both slow and fast twitch fibers decrease during 7 days of W, and 7 or 14 days of WBS. Density and area changes tended to reverse to control levels during 7 days of recovery (R) following WBS. Capillary density was increased with 7 days of W, and 7 or 14 days of WBS. During 7 days of R the capillary density returned toward control levels. In summary, the reduction in fiber cross sectional areas and increase in fiber and capillary densities support the hypothesis that in both forms of disuse, i.e., W and WBS, there is a loss in soleus muscle cell mass and not in fiber numbers.
这项工作是评估大鼠骨骼肌对失重以及后肢卸载的地面实验室实验反应的一系列努力的延续。比目鱼肌是一种慢肌纤维、承重（抗重力）肌肉。暴露于失重（W）以及全身悬吊（WBS）导致的运动减退/动力减退都会致使比目鱼肌萎缩。在失重7天以及全身悬吊7天或14天期间，慢肌纤维和快肌纤维的横截面积均减小。在全身悬吊后的7天恢复（R）期内，密度和面积变化倾向于恢复到对照水平。失重7天以及全身悬吊7天或14天会使毛细血管密度增加。在恢复的7天内，毛细血管密度恢复到对照水平。总之，纤维横截面积的减小以及纤维和毛细血管密度的增加支持了这样一种假说，即在两种废用形式下，即失重和全身悬吊，比目鱼肌细胞质量减少，而不是纤维数量减少。
