Role of cholinergic neuromuscular transmission in the neuroregulation of the autophosphorylatable regulatory subunit of cyclic AMP-dependent protein kinase type II and the acetylcholine receptor content in skeletal muscle.
Previously, we found that the in vitro [32P]-autophosphorylation of the regulatory subunit of cyclic AMP-dependent protein kinase type II in rat soleus muscles is subject to a nerve-stump-length-dependent neuroregulation which indicates that this event is dependent upon some neural signal other than the impulse-directed release of acetylcholine. In this investigation, tetrodotoxin and alpha-bungarotoxin were also administered to further differentiate the effect of impulse-directed and spontaneously released acetylcholine upon this event and also upon the appearance of new acetylcholine receptors as measured by the binding of radioiodinated bungarotoxin. A 24 h blockade of cholinergic transmission with either neurotoxin did not change the phosphorylation level of the regulatory subunit, while a significant increase is observed when solei are surgically denervated for this period. The phosphorylation level and also the acetylcholine receptor content were increased only after more prolonged (48-96 h) muscle inactivity was produced with the neurotoxins. However, then their effects may not be solely related to alterations in cholinergic transmission. Taken together, our results do not support a trophic role for spontaneously released acetylcholine with respect to the two neurotrophic events studied.
D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D002038:Bungarotoxins / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000032:analysis / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000502:physiology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000032:analysis*; D009435:Synaptic Transmission
D002038:Bungarotoxins; D011950:Receptors, Cholinergic; D011494:Protein Kinases; D000109:Acetylcholine