Fast repetitive stretch suppresses denervation-induced muscle fibrosis.

INTRODUCTION We aimed to examine the influence of different speeds of stretching on denervation-induced skeletal muscle fibrosis. METHODS Stretching was passively applied to rat plantaris muscle denervated by sciatic nerve excision in three different cycles of 0.5, 3 or 12 cycles/min, for 20 min/day for 2 weeks. RESULTS Gene analysis results showed greater expression of fibrosis-related factors with fast stretching compared with non-stretched muscle. Laser Doppler blood flow analysis indicated reduced intramuscular blood flow during stretching. Histological analysis demonstrated fibrotic area decreases in 12 cycles/min stretched muscle compared with non-stretched muscle. DISCUSSION Slower stretching induced greater mRNA expression of collagen and fibroblasts and greater decrement of blood flow. Histologically, faster stretching suppressed fibrosis. These results suggest that fast repetitive stretching of denervated muscle might suppress processes of muscle fibrosis.