Pharmacology Intramuscular injection of atropine causes initial bradycardia. The reason for this effect being seen is: A Stimulation of medullary vagal centre B Stimulation of vagal ganglia C Blockade of M2 receptors of SA nodal cells D Blockade of muscarinic autoreceptor on vagal nerve endings 💡 Explanation Intramuscular injection of atropine causes initial bradycardia. The reason for this effect being seen is: ✓ Correct Answer: D. Blockade of muscarinic autoreceptor on vagal nerve endings