Autonomic Pharmacology USMLE Step 1 Practice Question
A 58-year-old man with hypertension and a 3-year history of erectile dysfunction presents to his cardiologist, who initiates lisinopril 10 mg daily. Vital signs show BP 148/92 mmHg, HR 78/min, RR 16/min. After 6 weeks, his erectile function improves significantly. Serum creatinine is 0.9 mg/dL, potassium is 4.2 mEq/L, and fasting glucose is 98 mg/dL. Physical examination reveals no peripheral edema. He denies chest pain or dyspnea. Which of the following best explains the mechanism by which ACE inhibitors improve erectile function in this patient?
Answer choices
- AACE inhibitors block muscarinic receptors in the corpus cavernosum
- BACE inhibitors increase dopamine release from the hypothalamus
- CACE inhibitors directly stimulate phosphodiesterase-5 in corpus cavernosum
- DACE inhibitors increase sympathetic activity to improve penile tumescence
- EACE inhibitors reduce angiotensin II-mediated vasoconstriction, allowing improved penile blood flow and nitric oxide signalingCorrect answer
- FACE inhibitors increase bradykinin in the corpus cavernosum, directly stimulating cGMP production and penile smooth muscle relaxation
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