What is the mechanism of action for Lisinopril?

Lisinopril works primarily by inhibiting the renin-angiotensin system, which is a crucial regulatory system for blood pressure and fluid balance. Specifically, Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor. By blocking the conversion of angiotensin I to angiotensin II, a potent vasoconstrictor, it leads to dilation of blood vessels and a subsequent decrease in blood pressure. This mechanism is beneficial for conditions like hypertension and heart failure, as it decreases the workload on the heart and helps prevent further cardiovascular complications.

In contrast, other options describe mechanisms that do not apply to Lisinopril's action. For instance, calcium channel blockers function by preventing calcium from entering cells of the heart and blood vessel walls, which reduces heart contractility and dilates blood vessels. Meanwhile, blocking beta-adrenergic receptors primarily affects heart rate and contractility through the sympathetic nervous system. Lastly, promoting aldosterone secretion would lead to fluid retention and increased blood pressure, which is counterproductive to Lisinopril's intended effect. Thus, the selective inhibition of the renin-angiotensin system correctly identifies Lisinopril's therapeutic action.