Agents that activate protein kinase C reduce acetylcholine sensitivity in cultured myotubes.
We have examined acetylcholine (ACh)-elicited potentials or currents in current- or voltage-clamped cultured myotubes exposed to 12-O-tetradecanoyl-phorbol-13-acetate (TPA), a potent tumor promoter that activates protein kinase C. Although this agent had little action on either membrane resting potential or electrical resistance, a reversible decrease in ACh sensitivity was induced on 3-4-d-old chick myotubes. Depression of transmitter action by TPA was extended to 7-8-d mouse myotubes only when they were treated with phosphatidylserine. Glyceryl dioleate had effects on myotubes similar to those of TPA but with a reduced efficacy. We conclude that the activation of protein kinase C might be involved with the capacity of ACh receptors to respond to transmitter stimulation.
Eusebi
F
F
Molinaro
M
M
Zani
B M
BM
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D004594:Electrophysiology; D004789:Enzyme Activation / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009132:Muscles / Q000187:drug effects / Q000502:physiology*; D010704:Phorbols / Q000494:pharmacology*; D011493:Protein Kinase C; D011494:Protein Kinases / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D010704:Phorbols; D011950:Receptors, Cholinergic; D011494:Protein Kinases; D011493:Protein Kinase C; D000109:Acetylcholine; D013755:Tetradecanoylphorbol Acetate