Peripheral neural transmission: cholinergic (muscarinic) transmission Flashcards Preview

MODA > Peripheral neural transmission: cholinergic (muscarinic) transmission > Flashcards

Flashcards in Peripheral neural transmission: cholinergic (muscarinic) transmission Deck (12):
1

Acetylcholine

Non-selective muscarinic agonist
Only muscarinic agonist readily broken down by cholinesterases.

2

Carbachol

Non-selective muscarinic agonist

3

Muscarine

Non-selective muscarinic agonist
First isolated from fly agaric mushroom in 1869, no current use in UK.

4

Methacholine

Non-selective muscarinic agonist

2 isomers. Neither hydrolysed by BuChE
(+) methacholine is a substrate for AChE, and also ~200x more potent than the (-) isomer at muscarinic receptors

5

Bethanechol

Non-selective muscarinic agonist
Poorly absorbed from GI tract
Used systemically in bladder dysfunction.

6

Pilocarpine

Non-selective muscarinic agonist
Poorly absorbed from GI tract.

Treatment of glaucoma:
Administered by instillation as eye drops, readily absorbed across conjunctival membrane.
Contracts ciliary muscle -> produces traction on the trabecular meshwork, opens Canal of Schlemm-> facilitates aqueous humour drainage, lowering intraocular pressure.

7

Cevimeline

M3 selective agonist
Used to increase salivation & lacrimation in e.g dry mouth, Sjogren's syndrome (AI disease of glands that secrete fluid)

8

Atropine

Non-selective muscarinic antagonist
Produces dilatation of the pupils (mydriasis) for opthalmic examination/ cosmetic purposes.
Duration of action is v long, adrenoceptor agonists more suitable.

9

Benzilylcholine mustard

Non-selective muscarinic irreversible antagonist.

10

Pirenzepine

M1 selective antagonist

Had a wider use as an antisecretory agent in the treatment of gastroduodenal ulcers (was thought to act on intramural nerves serving the oxyntic cells)

11

Darifenacin

Selective M3 antagonist
(M3 receptors mediate bladder constriction)
Treatment of urinary incontinence.

12

Uses of muscarinic antagonists

Treatment of peptic ulcers until H2 histamine receptor blockers developed
Treatment of diarrhoea until opiate receptor agonist developed (effective in the enteric nervous system without significantly crossing BBB & acting centrally)

Used for premedication prior to anaesthesia.