BIOM 3090 Lecture Notes - Lecture 13: Acetylcholine Receptor, Parasympathomimetic Drug, Nicotinic Acetylcholine Receptor
9 Jun 2018
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Cholinergic drugs
Basic pharmacology and clinical applications of:
1) Cholinomimetics: mimic actions of ACh
a. Direcr (receptor agonists)
b. Indirect (AChE inhibitors)
2) Cholinergic antagonists:
a. Antimuscarinic
b. Antinicotinic
Direct acting cholinomimetics
1) esters of choline
a. acetylcholine
b. bethanechol
→ not absorbed/distributed well
2) Alkaloids:
a. Muscarinic
b. Nicotine
c. Pilocarpine
→ absorbed and distributed well, even in CNS
- cholinergic receptor agonists used clinically are not receptor sub-type
selective
- Receptor activation:
o Muscarinic: responses same as PSNS activation
▪ Sweat glands
▪ Endothelial derived relaxation of blood vessels
▪ Remember these receptors because they will be directly
activated by the drugs
o Nicotinic: activates PSNS and SNS
▪ Skeletal muscle contraction (nicotine: initially stimulates then
blocks)
▪ Nicotinic act on ganglion
o In different tissues, one of these systems will be more dominant
Muscarinic receptor agonists
- M3 and M5 receptors on endothelial cells
- Parasympathetic nerved do not innervate most blood
vessels but M receptors are prevent still… therefore
muscarinic agonists → vasodilation
Organ system effects muscarinic activation
- Pilocarpine is used to treat glaucoma (increase
intraocular pressure). What effect will it have in the
eye?
o M3 → contraction of sphincter muscle =
contraction of pupil (miosis) → contraction of
ciliary muscle (accommodation) opens up the
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