REN and acute kidney injury: Angiotensin-converting enzyme (ACE) inhibitors block the conversion of angiotensin I to a potent vasoconstrictor, angiotensin II, and can be used to treat renin-dependent hypertension.[8] They should, however, be used with caution in patients with ARF because of their potential to cause ARF in cases without preexisting renal disease.[18] Other antihypertensives that can be used include alphamethyldopa and calcium channel blockers.