What mode of action does losartan utilize to lower blood pressure?

Losartan is classified as an angiotensin II receptor blocker (ARB). By blocking the receptors for angiotensin II, it effectively prevents this hormone from exerting its potent vasoconstrictive effects on blood vessels. Angiotensin II typically causes blood vessels to constrict, leading to an increase in blood pressure. By inhibiting these receptors, losartan promotes vasodilation, which helps to lower blood pressure. This mode of action targets the specific pathway of the renin-angiotensin-aldosterone system (RAAS) where angiotensin II plays a critical role in regulating both blood pressure and fluid balance.

The other choices do not reflect the mechanism of action for losartan. For instance, blocking aldosterone receptors is the mechanism of action for a different class of drugs known as aldosterone antagonists. Preventing the conversion of angiotensin I to angiotensin II relates to the action of angiotensin-converting enzyme (ACE) inhibitors, while preventing renin secretion pertains to different types of medications that influence the RAAS at an earlier stage.