Pharmacology · single question

Nitroglycerin is used to treat angina pectoris. Its mechanism of action is BEST described as:

Inhibits beta-1 adrenergic receptors → reduces myocardial oxygen demand
Directly dilates coronary arteries by stimulating adenosine receptors
Blocks calcium channels in vascular smooth muscle → vasodilation
Metabolized to nitric oxide (NO) → increases cGMP → smooth muscle relaxation → vasodilation

Show answer and explanation

Correct answer: D. Metabolized to nitric oxide (NO) → increases cGMP → smooth muscle relaxation → vasodilation

A. Beta-blockers reduce myocardial oxygen demand by blocking beta-1 receptors — not the mechanism of nitroglycerin.
B. Adenosine receptor agonism is not the mechanism of nitroglycerin.
C. Calcium channel blockers (e.g., amlodipine, nifedipine) work by this mechanism — not nitroglycerin.
D. Correct. Nitroglycerin is a prodrug that is metabolized in vascular smooth muscle to nitric oxide (NO). NO activates guanylyl cyclase → increases cGMP → activates protein kinase G → phosphorylates myosin light chain kinase → smooth muscle relaxation → vasodilation. This reduces preload and dilates coronary arteries, relieving anginal pain.

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