There are two types of acetylcholine receptors:

Muscarinic receptors, M1-M5, are:

• Found in smooth muscle, glands, the heart and the brain
• G protein-linked; their actions are mimicked by muscarine
• Blocked by atropine

Nicotinic receptors

There are two types of acetylcholine receptors:

Muscarinic receptors, M1-M5, are:

• Found in smooth muscle, glands, the heart and the brain
• G protein-linked; their actions are mimicked by muscarine
• Blocked by atropine

Nicotinic receptors are:

• Found in the sympathetic ganglia and the motor end-plates of skeletal muscle
• Ligand-gated ion channel receptors; their actions are mimicked by nicotine, but unaffected by atropine

Question: When reversing non-depolarizing neuromuscular blockade, what classes of agent are given, and why?

Answer

There are two types of acetylcholine receptors:

Muscarinic receptors, M1-M5, are:

• Found in smooth muscle, glands, the heart and the brain
• G protein-linked; their actions are mimicked by muscarine
• Blocked by atropine

Nicotinic receptors are:

• Found in the sympathetic ganglia and the motor end-plates of skeletal muscle
• Ligand-gated ion channel receptors; their actions are mimicked by nicotine, but unaffected by atropine

Question: When reversing non-depolarizing neuromuscular blockade, what classes of agent are given, and why?

Answer: An anticholinesterase (neostigmine) is given to increase ACh levels. At the at the motor end-plate of the neuromuscular junction blocker (nicotinic) this reverses the effect of the muscle relaxant.

Unwanted muscarinic effects of the ACh are prevented by the use of an agent such as atropine or glycopyrrolate.