[Changes of acetylcholine receptor distribution at the motor end-plates following muscle transfer].

OBJECTIVE: To investigate the changes of acetylcholine receptor (AChR) distribution at the neuromuscular junction (i.e. motor end-plate) following the free neurovascular muscle transfer. METHODS: AChR in the gracilis muscle of the Wistar rat following free neurovascular transfer were labeled by fluorescent alpha-bungarotoxin and radioiodinated alpha-bungarotoxin. Then confocal microscope and gamma-counting were estimated to ACHR, qualitatively and quantitatively. RESULTS: The junctional AChR numbers decreased to a minimum at the fourth week postoperatively, whereas the extrajunctional receptor numbers increased. From the fifth week postoperatively, the number of junctional AChR's increased. Even at 30 weeks after transfer, the morphology of the neuromuscular junction failed to return to the preoperative style. The number of acetylcholine receptors at the reinnervated neuromuscular junction also remained lower than the control. CONCLUSION: The persistent weakness following free neurovascular muscle transfer may be attributed to these qualitative and quantitative changes at the neuromuscular junction.