What is the mechanism of action of nitroglycerin in treating angina?

Nitroglycerin functions primarily through vasodilation, which is the widening of blood vessels. When administered, nitroglycerin is converted into nitric oxide in the body, leading to relaxation of smooth muscles in the vascular wall. This vasodilation effectively reduces the preload on the heart by decreasing venous return, thereby lowering the myocardial oxygen demand. It also dilates coronary arteries, which improves blood flow to the heart muscle itself, alleviating symptoms of angina caused by ischemia.

This mechanism allows nitroglycerin to quickly relieve episodes of angina by addressing both the decreased oxygen supply to the myocardium and the increased oxygen demand during physical exertion or stress. The other options do not accurately reflect the primary action of nitroglycerin in the management of angina, as they involve different physiological processes unrelated to the drug’s action on blood vessels.