On the effect of muscle activity on the end-plate membrane in denervated mouse muscle.
1. Mouse soleus muscles were denervated and some of them were chronically stimulated. Sixteen to twenty-one days later, the number of junctional acetylcholine receptors (AChR) and their metabolic stability were examined by measuring binding of 125I-alpha-bungarotoxin, their gating properties by analysis of acetylcholine-induced current fluctuations and the ultrastructure of the end-plate membrane by electron microscopy. 2. In agreement with other studies on inactive muscles, no effect of denervation on junctional AChR number could be resolved. However, some of the fast-gating 'adult' AChR channels had been replaced by slowly gating fetal AChRs, their half-life was lowered to 38 h and the folding of the end-plate membrane was reduced. 3. These changes were prevented in denervated but stimulated active muscles: the junctional AChR population remained homogeneously 'adult', the half-life of junctional AChRs was 13 days and folding of the end-plate membrane remained comparable to that in control muscles. 4. The significance of these results is discussed with respect to the role of muscle activity in end-plate development.
Brenner
H R
HR
Department of Physiology, University of Basel, Switzerland.
Rudin
W
W
D000818:Animals; D002038:Bungarotoxins / Q000494:pharmacology; D003714:Denervation; D004558:Electric Stimulation; D051379:Mice; D008854:Microscopy, Electron; D009132:Muscles / Q000294:innervation* / Q000502:physiology; D009469:Neuromuscular Junction / Q000648:ultrastructure*; D011950:Receptors, Cholinergic / Q000378:metabolism*
D002038:Bungarotoxins; D011950:Receptors, Cholinergic