When the neurotransmitter acetylcholine is applied to skeletal muscle cells it a

Question

When the neurotransmitter acetylcholine is applied to skeletal muscle cells it activates the acetylcholine receptor that is a calcium ion channel causing the muscle cells to contract. In other words, acetylcholine is an agonist for the receptor. A similar molecule, succinylcholine, has been demonstrated to bind the same acetylcholine receptor on skeletal muscle cells and is sometimes used by surgeons as a muscle relaxant. Why does succinylcholine causes muscle relaxation instead of contraction, as acetylcholine does? In other words, what would you call succinylcholine?

Explanation / Answer

Succinyl is a non competitive nicotinic agonist i.e., it acts at a different site than acetylcholine but on the same receptor. In initial stage Succinylcholine causez depolarization and thus contraction just as acetylcholine. At the end, however acetylcholine breaks into acetyl and choline by acetyl cholinesterase and choline enters back into presynaptic nerve.

But this is not true for Succinylcholine. Succinylcholine maintains its depolarization, the muscle innervated by the nerve will relax. Due to depolarization of succinylcholine the acetylcholine is no longer to act or bind leading to paralysis.

Succinyl choline is therefore classified as depolarising neuromuscular blocker.

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