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Pharmacology · single question

Nitroglycerin's primary mechanism of action is:

  1. Converted to nitric oxide (NO) → activates guanylyl cyclase → increased cGMP → smooth muscle relaxation/vasodilation
  2. Blocks L-type calcium channels → reduced cardiac contractility
  3. Inhibits cyclooxygenase → reduced prostaglandin synthesis
  4. Stimulates beta-2 adrenergic receptors → vasodilation
Show answer and explanation

Correct answer: A. Converted to nitric oxide (NO) → activates guanylyl cyclase → increased cGMP → smooth muscle relaxation/vasodilation

Nitroglycerin (GTN) is metabolized to nitric oxide (NO) → activates soluble guanylyl cyclase → increased cyclic GMP (cGMP) → smooth muscle relaxation → vasodilation. It primarily dilates venous capacitance vessels (reducing preload) and coronary arteries (relieving vasospasm). Used for acute angina relief and hypertensive emergencies.
  • A. ✅ Nitroglycerin → NO → guanylyl cyclase → cGMP → vascular smooth muscle relaxation. Correct mechanism.
  • B. ❌ L-type calcium channel blockade is the MOA of calcium channel blockers (amlodipine, verapamil).
  • C. ❌ COX inhibition is the MOA of NSAIDs (ibuprofen, aspirin).
  • D. ❌ Beta-2 agonism is the MOA of albuterol (bronchodilator) — not nitroglycerin.

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