10 - NM Blocking Drugs

Question 1

Where do NM drugs act?

Answer 1

NOT in the autonomic nervous system. In the somatic nervous system.

alpha motor neurons (cell body)
vertebral column, ventral horns
single axons innervating muscles

Question 2

Outline the process of transmission

Answer 2

Choline acetyltransferase synthesizes ACh from choline + Acetyl CoA

Packaged in vesicles
AP (opening of VSCCs)
Exocytosis
Receptors on endplate region
Influx of Na+ (endplate potential) (graded potential) - all or nothing AP

The endplate region is approximately in the middle of skeletal muscle fibre

Acetylcholinesterase breaks down NT

Question 3

Are somatic nAChRs the same as ganglionic ones?

Answer 3

No

This has allowed drugs with a degree of selectivity to have been produced

Especially applies to antagonists
a1, a2, b1, y, d subunits in receptor
2ACh molecules need to bind (one to each alpha subunit)

Question 4

Give some examples of drugs that target somatic nAChRs

Answer 4

Tubocurarine, Atracurium - competitive

Suxamethonium - depolarizing