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BMS03 > Pharmacology Of Cholinergic Transmission > Flashcards

Pharmacology Of Cholinergic Transmission Flashcards

1
Q

What neurotransmitter is released at most autonomic synapses?

What is the exception?

A

Acetylcholine

Sympathetic (eg.blood vessels)

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2
Q

What is ACh formed from?

A

Choline

Acetyl coenzyme A

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3
Q

What enzyme catalyses the formation of ACh?

A

Choline acetyl transferase (CAT)

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4
Q

What is ACh stored in?

A

Pre-synaptic vesicles

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5
Q

By what process are the contents of pre-synaptic vesicles released?

A

Exocytosis

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6
Q

What causes the release of ACh?

A

Increased intracellular calcium ion concentration within nerve terminal

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7
Q

What are the two types of cholinergic receptor?

A

Muscarinic

Nicotinic

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8
Q

What enzyme catalyses the breakdown of ACh?

A

Acetylcholine-esterase (AChE)

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9
Q

Where is acetylcholine-esterase found?

A

In synaptic cleft tethered to post-synaptic membrane

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10
Q

What type of receptor is present at neuromuscular junctions?

A

Cholinergic nicotinic

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11
Q

What is the small brief depolarisation that occurs in the muscle fibre to trigger an action potential?

A

End plate potential

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12
Q

What causes sustained muscle fibre contraction?

A

Frequent action potentials

Causing twitch summation

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13
Q

What three pre-synaptic processes could be targeted to modify synaptic transmission?

A

Synthesis

Storage

Release

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14
Q

What drugs inhibit ACh synthesis?

A

Hemicholiniums

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15
Q

What enzyme do hemicholiniums inhibit?

A

Choline acetyl transferase (CAT)

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16
Q

What drug inhibits storage of ACh?

A

Vesamicol

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17
Q

What does vesamicol inhibit?

A

ACh storage

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18
Q

What inhibits the release of ACh?

A

Botulinum toxin

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19
Q

What is the (only) clinical use of nicotinic agonists?

A

Nicotine patches

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20
Q

What type of drug are muscle relaxants?

A

Reversible competitive antagonists of cholinergic nicotinic receptors

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21
Q

What are the properties of antagonists?

A

Have affinity but no efficacy

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22
Q

What do muscle relaxants do?

A

Bind to cholinergic nicotinic receptors on muscle fibres

Prevents ACh binding/activating receptor

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23
Q

What is an example of a skeletal muscle relaxant?

A

Vecuronium

Atracurium

Pancuronium

TUBOCURARINE

24
Q

Why are ganglion blockers not used clinically (often)?

A

Many side effects

25
Q

What is the major effect caused by ganglion blockers?

A

Reduction in blood pressure

26
Q

What is an example of a ganglion blocker?

A

Hexamethonium

Trimetaphan

27
Q

What is trimetaphan used for clinically?

A

Reduces bleeding during brain surgery

Reduces blood pressure

28
Q

What is botulism?

A

Paralysis (of respiratory muscles)

29
Q

What does botulinum toxin do?

A

Destroys key proteins involved in exocytosis (inhibiting release of ACh)

30
Q

What are some key proteins involved in exocytosis?

A

SNAP-25

Synaptobrevin

Syntaxin

31
Q

How many serotypes of botulinum toxin are there?

Which is most commonly used clinically?

A

7

Serotype A

32
Q

What is botulinum toxin used to treat?

A

Bletharospasm (involuntary tight closure of eyelids)

Bladder hyperreactivity

33
Q

Why is botulinum toxin injected locally?

A

Toxic in blood —> botulism

34
Q

What type of receptor alters ANS (especially parasympathetic) activity?

A

Muscarinic

35
Q

What are parasympathomimetics?

A

Muscarinic agonists that mimic effects of parasympathetic NS

36
Q

What are parasympatholytics?

A

Muscarinic antagonists that block effects of parasympathetic NS

37
Q

Why do drugs acting on muscarinic receptors tend to have side effects when given systemically?

A

Difficult to distinguish between subtypes

38
Q

Which glands are typically innervated by the sympathetic and parasympathetic NS?

A

S = sweat

P = salivary and others

39
Q

What are some effects of activating M3 receptors?

A

Pupil constriction/miosis

Ciliary muscle contraction

Lacrimal gland secretion

Airway smooth muscle constriction

Increased peristalsis

Detrusor contraction

Increased bronchial secretions

40
Q

Where is the M2 receptor found?

A

Heart/SAN

41
Q

What does activation of M2 cause?

A

Decreased heart rate

42
Q

What does M1 activation cause?

A

Gastric acid secretion

43
Q

What is bethanacol used for?

A

Stimulant laxative

Prevent constipation after surgery

44
Q

What are pilocarpine eye drops used to treat?

How?

A

Glaucoma

(Miosis and) contraction of ciliary muscle so suspensory ligaments lose tension

Lens becomes more spherical

Improves aqueous humour flow to reduce intraocular pressure (canal of Schlemm)

45
Q

What was the ‘pilocarpine sweat test’ used to diagnose in the past?

A

Cystic fibrosis

46
Q

What can atropine be used for? (2)

A

Sinus bradycardia (M2)

Preparing patients for surgery by reducing bronchial secretions (M3)

47
Q

What type of drug is atropine?

A

Muscarinic antagonist

48
Q

What drugs may be used to dilate the pupil?

A

Tropicamide

Cyclopentolate

49
Q

What drugs (parasympathetic) may be used to treat asthma (and other chronic obstructive pulmonary diseases)?

A

Ipratropium

Tiotropium

50
Q

What drug is used to treat motion sickness?

A

Hyoscine

51
Q

What drugs may be used to treat Parkinson’s disease?

A

Benzhexol

Benztropine

52
Q

What drug may be used to treat urinary incontinence?*

A

Tolterodine

Oxybutynin

53
Q

What is an example of an AChE inhibitor?

A

Neostigmine

Edrophonium

Dyflos

54
Q

How do AChE inhibitors affect transmission?

A

Prevent breakdown of ACh so increased ACh concentration in synaptic cleft

Enhances transmission in all autonomic ganglia and at parasympathetic neuroeffector junctions

55
Q

What are some physical effects of AChE inhibitors? (5)

A

Increased secretions (saliva, sweat, gastric acid, mucus, lacrimal)

Increased smooth muscle tone (bronchoconstriction, increased peristalsis)

Miosis (decreased intraocular pressure)

Bradycardia

Hypotension

56
Q

What drug is used to reverse the effects of muscle relaxants?

A

Neostigmine

57
Q

What is neostigmine used to treat?

A

Myasthenia gravis (autoimmune disease where autoAbs destroy nicotinic receptors)/neuromuscular weakness

BMS03 (12 decks)

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