Autonomic and Neuromuscular Pharmacology

Question 1

Describe inhibition of transmission at NMJ

Answer 1

Inhibit choline transporter 6-7
Block voltage gated Ca2+ channels 3
Block vesicle fusion (e.g. botulinium toxins) 4
Use non-depolarising nicotinic receptor blockers 5
Use depolarising nicotinic receptor blockers 5, agonist, keeps channel open, cell stays depolarised

Question 2

Describe potentiation at NMJ

Answer 2

Block acetylcholinesterase (e.g. eserine) 6
Wont be able to inactivate transmitter

Question 3

What are the clinical application of affecting transmission at NMJ

Answer 3

Non-depolarising/depolarising blockers used for paralysis in:
Surgical procedures
Electroconvulsive therapy
Controlling spasms in tetanus

Botulinum toxin
Treating muscle spasms
Cosmetic procedures

Anti-cholinesterases
Treating myasthenia gravis
Reversing action of non-depolarising blockers
Countering botulinum poisoning

Question 4

Describe muscarinic receptor agonists and antagonists

Answer 4

Muscarinic receptor agonists Mimic effect of parasympathetic system

Muscarinic receptor antagonists (e.g. atropine)
Block effects of parasympathetic system

(i.e. slow heart rate, contract smooth muscle in airways and bladder, increase gut motility, increase bronchial secretions and salivation, constrict pupil)

(therefore increase heart rate, relax smooth muscle in airways* and bladder, reduce gut motility, bronchial secretions and salivation, dilate pupil)

Question 5

Describe inhibition of Sympathetic postganglionic transmission

Answer 5

Block enzymes that produce noradrenaline
Introduce “false” transmitter
Activate inhibitory presynaptic (α2) autoreceptors (blocks voltage gated Ca+ channels)
Block α or β postsynaptic receptors

Question 6

Describe potentiating of Sympathetic postganglionic transmission

Answer 6

Stimulate noradrenaline release
Inhibit uptake into neurons or glia
Activate postsynaptic receptors

Question 7

What are the clinical appliction of affecting sympathetic transmission

Answer 7

α1 agonists as decongestants and to dilate the pupil (mydriatics)

α2 agonists for the treatment of hypertension

β2 agonists for the treatment of asthma

β1 antagonists for the treatment of hypertension, angina and cardiac arrhythmias