Which antianginal agent primarily acts by dilating the vascular smooth muscle?

Nitrates are a class of antianginal agents that primarily function by dilating vascular smooth muscle. This vasodilation occurs mainly through the conversion of nitrates to nitric oxide (NO), which relaxes smooth muscle in the blood vessels, leading to increased blood flow and decreased myocardial oxygen demand. By widening the blood vessels, nitrates effectively alleviate symptoms of angina, especially in conditions where the heart demands more oxygen, such as during physical exertion or stress.

In contrast, while beta-blockers can help manage angina by reducing heart rate and contractility, their primary mechanism does not involve direct vascular smooth muscle dilation. Calcium channel blockers also play a role in vasodilation but primarily do so by inhibiting calcium influx into vascular smooth muscle cells, rather than utilizing the nitric oxide pathway as nitrates do. Angiotensin II inhibitors focus on blocking the effects of angiotensin II, which primarily affects blood pressure and does not directly cause vascular smooth muscle dilation in the same way that nitrates do.