A 9-year-old girl is brought to the physician by her mother after an episode of difficulty breathing that occurred 2 hours ago that self-resolved after about 5 minutes. She also has a 1-year history of periodic dry cough. Vitals are normal. Pediatric development and history is otherwise unremarkable. The mother gets hay fever every spring, for which she takes an intra-nasal corticosteroid. Which of the following is the mechanism of action of the most appropriate initial pharmacologic therapy for this patient’s acute episodes?
A) Antagonizes G-alpha-q receptors
B) Antagonizes muscarinic receptors
C) Decreases cGMP
D) Increases cAMP
E) Inhibits phosphodiesterase
