| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
|
|---|
| Research Abstract |
The purpose of this study was to determine to how extent the stretched muscle length or the dynamic length change of muscle has an effect of preventing muscle atrophy. Four types of ankle splints were applied to one of the legs of the mouse, so as to the m. soleus length in situ was 1) immobilized in shortened position (IS), 2) immobilized in lengthened position (IL), 3) allowed to change only within shortened range (ES), or 4) allowed to change only within lengthened range (EL). After six-weeks' treatment, muscles were isolated, and the muscle length in situ, muscle mass, and the contractile properties were determined.
In all groups, the muscle mass of the splinted legs was less than that of controls. However, the decrease of the mass was less in muscles allowed their partial movements especially in lengthened range. Greater passive tension was observed only in the shortened-length muscles (IS and ES). The maximal rate of tension development was integrated in muscles allowed their partial movements (ES and EL). The normalized isometric length-tension relationship didn't change in all muscles except the slight tension enhancement at longer lengths observed in the muscle fixed at stretched position (IL). The data shows that the dynamic muscle movement may have a stronger effect of preventing muscle atrophy than stretching muscles, and the contractile properties are preserved when the muscles are allowed to contract dynamically.
|
