| To determine the independent contribution of axotomized neuron, denervated distal nerve stump and denervated muscles to poor functional recovery after delayed nerve repair, quantitative electrophysiological and nerve graft techniques were used in a rat model of peripheral nerve injury. In rat hindlimbs, either tibial (TIB) nerve was cut, a common peroneal (CP) nerve sheath denervated or Tibialis Anterior (TA) muscle denervated for periods of up to 12 months prior to repair. Tibial nerve regeneration was initiated by cross-anastomosis of TIB nerves to CP nerve via a contralateral CP autograft. At least 6 months after the nerve repair, the outcome of nerve regeneration was assessed by measuring how many motor nerve fibers make functional nerve-muscle contacts (motor unit number; MUN) and their ability to branch (motor unit force). Functional recovery was further assessed by whole muscle maximal isometric force, muscle weight, total number of muscle fibers, muscle fiber size and distribution pattern of glycogen-depleted motor units. (Abstract shortened by UMI.). |
