Extrajunctional acetylcholine receptors on myogenously de=innervated muscle fibers.

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Abstract
To provide visualization of extrajunctional AChR [acetylcholine receptor] in a myogenously dysinnervated model, a central narrow crush lesion of the sternohyoid muscle was performed in anesthesized male rats just distal to the motor endplate zone of innervation. This allowed examination of a proximal innervated segment and of an apparently viable, structurally intact, nondegenerating distal muscle fiber segment parted from neural influence myopathically. Fresh-frozen muscle was evaluated 1-17 days thereafter by light microscopy for the presence of extrajunctional AChR by the .alpha.BT[bungarotoxin]-immunoperoxidase technique. The recovering original fiber segments distal to the crush were essentially normal, although an occasional fiber had an internal nucleus. In spite of this they all had extrajunctional AChR diffusely throughout the sarcolemma as early as 4 days.