A 58-year-old man with newly diagnosed hypertension, type 2 diabetes, and microalbuminuria is started on ramipril. Which mechanism best explains the renoprotective effect of ACE inhibitors independent of blood pressure lowering?
- A Increased bradykinin-mediated vasodilation of the efferent arteriole
- B Inhibition of aldosterone reducing systemic vascular resistance
- C Preferential vasodilation of the efferent glomerular arteriole reducing intraglomerular pressure ✓
- D Reduced sodium reabsorption in the distal convoluted tubule
Correct answer: C. Preferential vasodilation of the efferent glomerular arteriole reducing intraglomerular pressure
Explanation
ACE inhibitors dilate the efferent arteriole of the glomerulus more than the afferent arteriole, reducing intraglomerular hypertension and proteinuria. This hemodynamic effect is independent of systemic blood pressure reduction and explains renoprotection in diabetic nephropathy. ARBs share this property and are equally acceptable alternatives if ACE inhibitors are not tolerated.
Reference: Brenner and Rector's The Kidney, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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