Autonomic Pharmacology USMLE Step 1 Practice Question
A 68-year-old man with hypertension and heart failure presents to clinic with a persistent dry cough that began 3 weeks after initiating lisinopril 10 mg daily. His vital signs are stable (BP 138/82 mmHg, HR 72, RR 18), oxygen saturation is 98% on room air, and lung examination reveals clear bilateral breath sounds without wheezing or crackles. Chest X-ray shows no acute infiltrates or pulmonary edema. Serum creatinine remains 1.1 mg/dL (baseline). The lisinopril is discontinued and losartan is started instead. The patient's cough resolves within 10 days. Which of the following best explains why angiotensin II receptor antagonists do not cause the same adverse effect as ACE inhibitors?
Answer choices
- AARBs directly block renin secretion, preventing angiotensin I formation
- BACE inhibitors cause accumulation of bradykinin in pulmonary tissue, whereas ARBs do not inhibit bradykinin-degrading enzymesCorrect answer
- CAngiotensin II receptor blockade increases substance P degradation in airway sensory nerves
- DARBs inhibit angiotensin-converting enzyme more selectively than ACE inhibitors, sparing bradykinin metabolism
- EARBs suppress cough reflex sensitivity by directly blocking nicotinic receptors on vagal afferent nerves
- FLosartan and other ARBs have greater selectivity for AT2 receptors, which mediate bronchial smooth muscle relaxation
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