ACE inhibitors block the conversion of angiotensin I to what substance?

ACE inhibitors, or Angiotensin-Converting Enzyme inhibitors, are primarily used to manage conditions such as hypertension and heart failure. Their mechanism of action involves blocking the conversion of angiotensin I, an inactive precursor, into angiotensin II, a potent vasoconstrictive peptide.

Angiotensin II serves multiple functions, including increasing blood pressure by causing blood vessels to constrict and stimulating the secretion of aldosterone, which leads to sodium and water retention. By inhibiting the formation of angiotensin II, ACE inhibitors reduce vasoconstriction and promote vasodilation, ultimately lowering blood pressure and reducing the workload on the heart.

While other options may be related to the renin-angiotensin-aldosterone system, they do not represent the direct product of the conversion that ACE inhibitors block. This is why angiotensin II is correctly identified as the substance whose formation is inhibited by ACE inhibitors.