Rapid fast to slow fiber transformation in response to chronic stimulation of immobilized muscles of the rabbit.

摘要: Abstract Limb immobilization causes muscle atrophy particularly of slow oxidative fibers which also suffer the greatest decrement in neural activation. In this study a fast muscle, tibialis anterior, was chronically stimulated using an activity pattern characteristic nerve to muscles see whether or not could prevent induced fiber atrophy. Four groups rabbits were used: unoperated controls, (10 Hz, 8 h/day), immobilized (neutral position), and plus group. The experimental period 28 30 days 44 50 days. Immobilization caused significant decrease area completely prevented by stimulation. animals tested for longer there 56% hypertrophy. addition, combination stimulation two-fold increase number greatly increased proportion intermediate fibers. Stimulation without had no effect. Slow bimodal distribution; large (mean 7059 μm2) same as contralateral muscles, suggesting that they preexisting fibers, small population 3143 represented newly converted We conclude units benefit from restoration chronic accelerates conversion. suggest isometric conditions well enhanced glucocorticoid effects account these findings.