acetylcholine
    n 1: a neurotransmitter that is a derivative of choline;
         released at the ends of nerve fibers in the somatic and
         parasympathetic nervous systems

acetylcholine \acetylcholine\ n.
   1. a neurotransmitter released by the transmitting dendron at
      autononmous synapses and at neuromuscular junctions. It is
      a quaternary amine with an obligatory negative counterion.
      The nominal formula for the hydroxide form is C7H17NO3.
      Structural formula (CH3)3N(+)CH2CH2.O.CO.CH3.OH(-).

   Note: Acetylcholine is the first recognized and best-studied
         of the neurotransmitters. At receptors it is recycled
         into choline by the action of acetylcholinesterase.
         Acetylcholinesterase inhibitors therefore function as
         nerve poisons. For biochemical studies it is prepared
         typically in the chloride or bromide forms.
         [WordNet 1.5 +PJC]