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Neuromuscular junction transmission — FRCA Primary MCQ

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ModeratePhysiologyNeuromuscular junction transmissionFRCA Primary

During recovery from non-depolarising blockade, a patient has fade on train-of-four stimulation. Which physiological process at the motor nerve terminal is most relevant to fade?

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Correct answer: B — Reduced presynaptic acetylcholine mobilisation

Train-of-four fade reflects impaired presynaptic nicotinic receptor function and reduced mobilisation of acetylcholine during repeated stimulation. Skeletal muscle calcium release relates to excitation-contraction coupling rather than fade. Reduced axonal sodium conductance would impair each impulse more uniformly. Understanding fade helps distinguish non-depolarising from phase I depolarising block.

Reference: Ganong Review of Medical Physiology; Peck, Hill & Williams Pharmacology