Neuromuscular blocking drugs

Question 1

Outline neuromuscular transmission

Answer 1

Acetylcholine in vesicles = wait for AP = depolarise terminal = open calcium channels = stimulate the exocytosis of Ach = diffuse towards the post synaptic terminal = ach stimulates nicotinic (type 1 – ion channels) = influx of sodium into the fibre = end plate potential is created (graded)

Question 2

How is ACh reproduced

Answer 2

Breakdown of Ach (via acetylcholinesterase) => choline and acetic acid => choline uptake => acetyl + choline bind via cholineacetyl transferase

Question 3

Agents that reduce Ach release (BAHM)

Answer 3

Hemicholinium (blocks choline uptake)

Botulinum toxin

Aminoglycosides

Mg2+/Co2+

Targets Ca2+ influx

Question 4

Agents that potentiate transmission (5)

Answer 4

Anticholinesterases

Pyridostigmine

Neostigmine

Edrophonium

Distigmine

Physostigmine

Question 5

Competitive neuromuscular blocking drugs

Answer 5

Tubocurarine

vecuronium

Pancuronium

Alcuronium

Atracuronium

Gallamine

Question 6

Depolarising neuromuscular drugs

Answer 6

Suxamethonium

Slows dissociation

Question 7

Describe the action of a nicotinic acetylcholine receptor (nAChR)

Answer 7

2 alpha subunits stimulated by ACh

Extracellular and intracellular domain

Stimulation causes Na+ influx = end plate potential until channel rapidly closes

Question 8

Sites of drug action: central process

Answer 8

Spasmolytics (diazepam/baclofen)

relaxation of skeletal muscle

Question 9

sites of drug action: conductioi