| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1997: ¥1,200,000 (Direct Cost: ¥1,200,000)
|
|---|
| Research Abstract |
As the immobilization of muscle in stretched position have an effect on preventing muscle atrophy, it is thought that the stretch is one of the important determinants of muscle hypertrophy. However it is also known that the much greater hypertrophy is induced by muscle contractions than only by a passive tension without muscle movement. To determine to how extent the muscle movement without passive tension have an effect on muscle hypertrophy, two experiment were carried out ; 1) in the cultured cell, and 2) in the skeletal muscle in vivo.
1) Chronic passive shortening was applied on cultured skeletal myotube cells. Myoblast and fibroblast cells from the new born rat were plated onto the preliminary stretched collagen-coated silicone sheet and cultured for four days. After myotube differentiation was induced, passive shortening by 2% of the length and its recovery to the first length were applied at every five seconds, while the control cells were cultured silently. After four-days 'exercise', cells were collected from the sheet and their protein component was analyzed. SDS-PAGE revealed a slight increase in the protein of 6OkDa, while no change was observed in other molecular weight components of the protein.
2) A splint which restricts the muscle movement of the lower limb partially in the shortened or stretched position was administrated on one of the legs of a mouse. After five-weeks' treatment, muscles from both a splinted leg and a contralateral leg were isolated, and the muscle properties were determined. The muscle mass of the splinted legs was less than that of controls, and the decrease of the mass were greater in shortened-exercise muscle than in stretched-exercise muscle. Greater passive tension was observed only in the shortened-exercise muscle, and the normalized isometric length-twitch tension relation didn't changed in both of the exercise-restricted groups.
|
