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ChAT Enzyme — FRCA Primary MCQ

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HardPhysiology - NeurophysiologyChAT EnzymeFRCA Primary

At a cholinergic nerve terminal, vesamicol inhibits the vesicular acetylcholine transporter. Which consequence is most likely with repeated nerve stimulation?

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Correct answer: D — Reduced quantal acetylcholine release despite preserved cytosolic synthesis

The best answer is “Reduced quantal acetylcholine release despite preserved cytosolic synthesis”. Vesamicol blocks loading of acetylcholine into synaptic vesicles, so cytosolic synthesis may continue but releasable quantal transmitter falls during stimulation. Hemicholinium impairs high-affinity choline uptake and hence synthesis. Acetylcholinesterase inhibitors prolong synaptic action. Neither vesamicol nor choline-acetyltransferase inhibition is a direct nicotinic-receptor antagonist.

Reference: RCoA, Primary FRCA syllabus: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf; The Vesicular Acetylcholine Transporter Is Required for Neuromuscular Development and Function: https://pmc.ncbi.nlm.nih.gov/articles/PMC2747982/