ACEi Efferent Dilation GFR Drop — FRCA Primary MCQ

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HardPhysiology - RenalACEi Efferent Dilation GFR DropFRCA Primary

ACE inhibitors reduce GFR in patients with renal artery stenosis because:

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Correct answer: C — They dilate the efferent arteriole reducing glomerular capillary pressure

In renal artery stenosis the kidney maintains GFR by angiotensin II-mediated efferent arteriolar constriction which sustains glomerular capillary pressure. ACE inhibitors block AII formation / dilate the efferent arteriole / and reduce glomerular capillary pressure potentially causing acute kidney injury. This is why ACEi/ARBs are used cautiously in bilateral renal artery stenosis.

Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist