What is the mechanism of action for nitroglycerin?

• A. It increases heart rate
• B. It dilates blood vessels, reducing the heart's workload
• C. It constricts blood vessels
• D. It increases blood pressure

Answer: (B)

Nitroglycerin primarily acts by dilating blood vessels, which leads to a decrease in the workload on the heart. This vasodilation is achieved through the conversion of nitroglycerin to nitric oxide, a potent vasodilator. As blood vessels relax and widen, there is a reduction in vascular resistance, which lowers the amount of oxygen the heart needs to function. This is particularly beneficial in cases of angina, where the heart is not receiving enough oxygen due to narrowed arteries.

In addition to relieving angina symptoms, this mechanism helps manage conditions such as heart failure and acute myocardial infarction (heart attacks) by optimizing blood flow and decreasing oxygen demand on the heart. Ultimately, the goal is to alleviate chest pain and improve overall cardiac efficiency without causing undue stress on the heart muscle itself.