Effect of unilateral damage to sciatic nerve on phenotype of lumbrical muscles in experimental and contralateral legs in rats.

Expression of slow myosin in fast lumbrical muscle during unilateral damage to the sciatic nerve was studied in rats. Four weeks after unilateral excision of sciatic nerve segment or its crushing, the content of slow fiber in the lumbrical muscle of the contralateral leg tended to increase (detected using monoclonal antibodies against slow myosin). The extrapyramidal system seems to modulate the phenotype of muscle fibers via motoneurons of the spinal cord, while the compensatory activation of this system manifests in pronounced "deceleration" of both the fast and slow muscles in the hind legs.