Pharmacology Botulinum toxin blocks neuromuscular transmission by the following mechanism: A Closure of Ca++ channels at presynaptic membrane B Closure of Na+ channels at the postsynaptic membrane C Opening of K+ channels at the presynaptic membrane D Opening of Cl- channels at the postsynaptic membrane 💡 Explanation Botulinum toxin blocks neuromuscular transmission by the following mechanism: ✓ Correct Answer: A. Closure of Ca++ channels at presynaptic membrane