Which of the following is a listed use of muscarinic selective agonists?

• A. Pupil constriction
• B. Bronchodilation
• C. Inhibition of gastric acid secretion
• D. Increased urination

Answer: (A)

Muscarinic selective agonists mimic parasympathetic activation by stimulating M receptors in target tissues. A classic effect is pupil constriction (miosis) due to activation of the iris sphincter muscle via M3 receptors. This ocular action is exploited therapeutically in glaucoma to increase outflow of aqueous humor and lower intraocular pressure, with drugs like pilocarpine as typical examples.

Bronchoconstriction — not bronchodilation — occurs with muscarinic activation in the airways, so bronchodilation is not a listed therapeutic use. Gastric acid secretion is actually stimulated by muscarinic activation on gastric parietal cells, so inhibition wouldn’t be a use. Increased urination can occur and is a possible therapeutic effect in urinary retention, but the most recognized listed use among the options is pupil constriction for glaucoma.