Final answer:
Nitroglycerin's primary action is as a vasodilator, due to its ability to trigger the release of nitric oxide, which causes blood vessels to dilate and improves blood flow to the heart.
Step-by-step explanation:
The action of nitroglycerin is primarily as a vasodilator. Nitroglycerin works in the treatment of heart disease by triggering the release of nitric oxide (NO), a gas that functions as a ligand. NO diffuses directly across the plasma membrane and interacts with smooth muscle receptors, inducing relaxation. This relaxation leads to the dilation of blood vessels, particularly the coronary arteries, restoring blood flow to the heart muscle and reducing the symptoms of angina.
While it has other potential benefits, such as decreasing blood pressure by increasing glomerular filtration rate and decreasing sodium reabsorption in the kidneys, the primary action of nitroglycerin in acute settings, like a myocardial infarction (heart attack), is to improve blood flow to the heart via vasodilation. Other treatments for myocardial infarction may include aspirin for its antiplatelet effect, as well as more long-term treatments to address the underlying causes of heart disease.