Atropine is used to reverse bradycardia during general anesthesia. Which of the following effects would atropine NOT be expected to produce?

• A Increased heart rate through SA node M2 blockade
• B Dilation of bronchi through M3 blockade
• C Reduced salivary secretion
• D Pupillary constriction (miosis) in the eye ✓

Explanation

Atropine blocks muscarinic M3 receptors in the iris sphincter pupillae, preventing acetylcholine-induced constriction, which leads to mydriasis (pupillary dilation), not miosis. Miosis is produced by muscarinic agonists or anticholinesterases. Atropine increases heart rate via M2 blockade at the SA node, causes bronchodilation via M3 blockade in bronchial smooth muscle, and reduces all secretions including salivary.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.