Nictotinic Acetylcholine Receptor (nAChR) Flashcards Preview

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Flashcards in Nictotinic Acetylcholine Receptor (nAChR) Deck (7):
0

Subfamily

Pentametric Ligand-gated Receptors (GABAaR, GlyR, and 5-HT3R)

1

Function

Non-selective cation channel, allows Na and other cations, strictly impermeable to anions. Results in depolarization and AP in neurons and muscle cells

2

Agonists

ACh, Nicotine, Choline, carbachol, etc
*Needs two molecules of ACh to bind for activation
*Dissociation of ACh is slow, so channel may open and close several times before the ACh is removed
* Agonist usually remain bound until the channel closes, then they leave.

3

Antagonists

alpha-bungarotoxin (snake venom), tubocurarine (arrow head poison for South American Indians) - Competitively and irreversibly block nAChR = spastic paralysis, respiratory failure, and death.
*Synthesized antagonists include mecamylamine and memantine.

4

Desensitization

Prolonged or repeated exposure to ACh can result in desensitization and lack of response. Can also desensitize due to receptor phosphorylation by PKA or PKC

5

Neuromuscular Junction

ACh usually acts as a messenger at the neuromuscular junction, results in depolarization of the muscle cell and generation of an AP.

6

nAChR in the CNS

Endogenous ACh and exogenous nicotine facilitate DA release in the brain (elevating mood)
Mecamylamine is a non-competative antagonist used for smoking cessation