Which of the following cause an increase in ACh release from the presynaptic neuron?
(A) Blocking calcium channels on presynaptic (B) Blocking chloride channel on presynaptic (C) Blocking Na channel (D) Blocking K channels
(D) Ans. D. Blocking K channels* Potassium channel blocker will cause an increase in ACh release from the presynaptic neuron.* Blockade of presynaptic potassium channels promotes activation of voltage-gated calcium channels leading to the increased release of acetylcholine in the neuromuscular junction. Aminopyridines used in the treatment of Lambe-Eaton myasthenic syndrome acts by this mechanism and improves the muscle strength in the patients