Biochemical and physiological changes in overloaded rat fast- and slow-twitch ankle extensors.
Biochemical and physiological changes in overloaded rat fast- and slow-twitch ankle extensors.
复制标题
超负荷大鼠快肌和慢肌踝伸肌的生化和生理变化。
DOI：
10.1152/jappl.1985.59.2.639
复制
发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Edgerton,VR
中科院分区：
文献类型：
--
作者：
Roy,RR;Baldwin,KM;Martin,TP;Chimarusti,SP;Edgerton,VR
大鼠比目鱼肌（SOL）或内侧腓肠肌（MG）的慢性超负荷通过去除其主要的协同双边。12-14周后，超负荷SOL（OS）和超负荷MG（OMG）肌肉的横截面积（CSA）比对照组增加约50%。与正常SOL相比，OS的最大抽搐（Pt）和强直（Po）张力约大46%。OMG产生的Pt和Po分别高出10%和37%。两组的比张力（Po/CSA）均未改变（P> 0.05）。收缩时间和半松弛时间不变。肌原纤维和肌球蛋白ATP酶的比活性表明，在OS和红色部分，但不是OMG的白色部分类似于一个较慢的肌肉的转变。一般来说，糖原代谢的标志物减少（P <0.05），在相同的肌肉区域，显示ATP酶活性降低。这些生化结果与这些肌肉区域的快收缩、糖酵解-快收缩、氧化-糖酵解-慢收缩、氧化型纤维的明显组织化学转换相一致。这些结果表明，超载无论是快速或缓慢收缩跖屈肌的肌肉质量和最大张力的增加和代谢的变化，一般类似于在一个较慢的肌肉中观察到的结果。此外，适应程度似乎与肌肉和/或肌肉区域的初始纤维类型组成有关。
The rat soleus (SOL) or medial gastrocnemius (MG) were chronically overloaded by removing their major synergists bilaterally. After 12–14 wks the overloaded SOL (OS) and overloaded MG (OMG) muscles had approximately 50% greater cross-sectional areas (CSA) than the controls. Maximum twitch (Pt) and tetanic (Po) tensions were approximately 46% larger in the OS compared with the normal SOL. The OMG produced 10 and 37% higher Pt and Po, respectively. Specific tension (Po/CSA) was not altered in either group (P greater than 0.05). Contraction times and half-relaxation times were unchanged. Myofibrillar and myosin ATPase specific activities indicated a shift toward that resembling a slower muscle in both the OS and the red portion but not the white portion of the OMG. Generally, markers of glycogen metabolism were reduced (P less than 0.05) in the same muscle areas that showed reduced ATPase activity. These biochemical results were consistent with the apparent histochemical conversion of fibers from fast-twitch, glycolytic----fast-twitch, oxidative-glycolytic----slow-twitch, oxidative types in these muscle areas. These results suggest that overloading either a fast- or slow-twitch plantarflexor results in an increase in muscle mass and maximum tension and in metabolic shifts that generally resemble those observed in a slower muscle. Further, the degree of adaptation appears to be related to the initial fiber type composition of the muscle and/or of the muscle region.