Do endplate noise and spikes arise from normal motor endplates?
The concept that the endplate noise and endplate spike components of motor endplate potentials represent normal endplate potentials seems to be flawed. The morphology of the normal miniature endplate potentials described in the physiology literature is different from the morphology of the noise-like component of endplate potentials. This noise-like component is identified as normal in current electromyographic literature. There is strong experimental evidence that one source of the endplate noise component is grossly increased release (up to three orders of magnitude) of acetylcholine from the nerve terminal of that neuromuscular junction. The spikes can be accounted for by release of additional acetylcholine in response to mechanical stimulation by the electromyographic needle. Other possibilities exist.
Simons
D G
DG
Department of Rehabilitation Medicine, Emory University, Atlanta, Georgia, USA.
D000200:Action Potentials; D000818:Animals; D004576:Electromyography; D006801:Humans; D009045:Motor Endplate / Q000502:physiology*