Cholinergic Drugs and Neuromuscular Blockers

Question 1

What receptors do cholinergic drugs act on?

Answer 1

ACh receptors (exist in PNS, SNS, and somatic nervous systems)

Question 2

What are the 5 steps of the ACh life cycle? and where does each step occur?

Answer 2

1. Synthesis (presynaptic cell)
2. Storage (presynaptic cell)
3. Release (presynaptic cell)
4. Receptor binding (postynaptic cell)
5. Degradation (synaptic cleft)

Question 3

What happens in the synthesis step (1st) of the ACh life cycle?

Answer 3

The enzyme choline acetyl tranferase uses the precursors acytel coenzyme A and choline to make ACh

Question 4

What happens in the storage step (2nd) of the ACh life cycle?

Answer 4

ACh is loaded into synaptic vesicles where it is protected from degradation and also kept in a ready to release format

Question 5

What happens in the release step (3rd) of the ACh life cycle?

Answer 5

Occurs in response to an action potential that signals synaptic vesicle fusion with the synaptic membrane. 100 or more vesicles fuse in one signaling event. ACh is released into synaptic cleft.

Question 6

What happens in the receptor binding step (4th) of the ACh life cycle?

Answer 6

2 types of ACh receptors: nAChR and mAChR

Question 7

What happens in the degradation step (5th) of the ACh life cycle?

Answer 7

Enzyme Acetylcholinesterase (ACE) metabolizes ACh into choline and acetate, in an extremely fast and efficient reaction, w/in 150 microseconds of release. Choline is scavenge by transporters on the presynaptic cell and is recycled to make more ACh.

Question 8

What drugs act on Muscarinic ACh receptors?

Answer 8

1. Bethanechol (agonist)
2. Carbachol (agonist)
3. Prilocarpine (agonist)
4. Atropine sulfate (antagonist)
5. Scopolamine (antagonist)

Question 9

What drug acts on the metabolic pathway: ACE inhibitors?

Answer 9

Neostigmine

Question 10

What drugs act as neuromuscular blockers?

Answer 10

1. D-tubocurarine

2. Succinylcholine