A regenerating release of acetylcholine from mouse motor nerve terminals treated with anticholinesterase agents.
It was found by intracellular recording with glass microelectrodes that train stimulation (50-200 Hz) of the phrenic nerve of intact or cut mouse diaphragm induced an accumulative depolarization of the endplate and triggered after a few pulses an 'all-or-none' regenerative depolarization lasting for 300-900 ms when acetylcholinesterase was inhibited by neostigmine or diisopropylfluorophosphate. This depolarization was associated with a noise of the membrane potential and a failure of the end plate potential. Low Ca2+ prolonged whereas high Ca2+ shortened the duration of regenerative depolarization which needed no further stimulation once triggered. d-Tubocurarine abolished the depolarization while restoring the end plate potential. A regenerative release of acetylcholine due to an activation of presynaptic cholinoceptors is speculated.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D004558:Electric Stimulation; D005071:Evoked Potentials; D007531:Isoflurophate / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008813:Mice, Inbred ICR; D009045:Motor Endplate / Q000187:drug effects* / Q000502:physiology; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D009388:Neostigmine / Q000494:pharmacology; D009469:Neuromuscular Junction / Q000187:drug effects*; D010791:Phrenic Nerve / Q000187:drug effects / Q000502:physiology*
D002800:Cholinesterase Inhibitors; D007531:Isoflurophate; D009388:Neostigmine; D000109:Acetylcholine