3. Old stuff
          3.1. Old pharm stuff (pre 2009)
              3.1.4. Physiology
                  3.1.4.2. Neurophysiology
 3.1.4.2.3. Acetylcholine 

Acetylcholine

[WG21:p101-103]

=== Unfinished ===

Need to consolidate and re-organise some of the stuff from [Neuromuscular junction], [Acetylcholine] and [Receptors]

 

Botulinum toxin works by inhibition of ACh synthesis and release [???]

 

 

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  • Acetylcholine is acetyl ester of choline

Synthesis of acetylcholine

Reaction
= Choline + Acetyl-CoA --> Acetylcholine --> Choline + Acetate

 

NB:

  • Acetylcholine, after formation, is taken up into synaptic vesicles by a vesicular transporter VAChT

Enzymes involved

  • Formation of acetylcholine is catalysed by choline acetyltransferase
    * High concentration in cytoplasm of cholinergic nerve endings
  • Breakdown of acetylcholine is catalysed by acetylcholinesterase

NB:

  • Choline is actively taken up via a transporter into cholinergic neurons
    * The transporter is a sodium dependent carrier protein, blocked by hemicholinium [BGK9:p78]
  • Choline is also synthesised in neurons

Catabolism of acetylcholine

  • Acetylcholine is rapidly broken down in the synapse
    * By hydrolysis which is catalysed by acetylcholinesterase
    * Into choline and acetate
    * Choline is actively taken up by the motor nerve ending
  • Acetylcholinesterase is located in neuromuscular junction
  • ACh is also broken down by plasma cholinesterase to lesser extent [SH4:p263]