Autonomic and Neuromuscular Pharmacology

Question 1

Synaptic transmission in the ANS

Answer 1

Transmitter synthesised and packaged into vesicles
Na action potential evokes Ca dependent exocytosis of vesicles
Transmitter binds to iontropic and/or metabotropic receptors on the post-synaptic membrane
Transmitter also binds to presynaptic autorecptors which inhibit voltage gated Ca channels and curtail further transmitter release
Transmitter is inactivated and is metabolised within cells

Question 2

Synaptic transmission in the NMJ

Answer 2

ACh transmitter, receptors all nicotinic (but different from the autonomic ganglia)
Released ACh is broken down by acetylcholinesterases into acetate and choline
Taken back up into neurones and recycled into new ACh

Question 3

Hemicholinium

Answer 3

Blocks choline transport (affects all cholinergic synapses)

Question 4

Black widow spider toxin

Answer 4

Blocks voltage-gated Ca channels

Question 5

D-tubocurarine

Answer 5

Competitive antagonist to stop ACh activating the post-synaptic nicotinic receptors

Question 6

Botulinum toxin

Answer 6

Prevents vesicle fusion