Final answer:
Nitrates such as nitroglycerin alleviate anginal pain through vasodilation of coronary arteries, which improves blood flow and oxygen delivery to the heart muscle.
Step-by-step explanation:
Anginal pain is relieved with nitrates such as nitroglycerin primarily through the mechanism of vasodilation of coronary arteries. Nitroglycerin acts by triggering the release of nitric oxide, a vasodilator that causes blood vessels to dilate (expand), allowing for improved blood flow to the heart muscle and relieving the pain associated with the reduced blood flow in coronary arteries, known as angina. By dilating the coronary vessels, the medication helps to alleviate the oxygen deprivation that the heart muscle experiences during bouts of angina.