What effect does RAAS activation have on the kidney, and how do ACE inhibitors alter this?

• A. RAAS activation increases glomerular pressure and promotes fibrosis; ACE inhibitors reduce proteinuria and slow progression.
• B. RAAS activation decreases glomerular pressure; ACE inhibitors worsen progression.
• C. ACE inhibitors have no effect on proteinuria.
• D. RAAS activation reduces fibrosis; ACE inhibitors increase proteinuria.

Answer: (A)

RAAS activation raises angiotensin II, which constricts the efferent arteriole of the glomerulus. This raises intraglomerular pressure, increasing filtration pressure and, over time, promoting proteinuria and fibrotic changes in the kidney. ACE inhibitors block the formation of angiotensin II, causing efferent arteriole dilation and a drop in intraglomerular pressure. The result is less protein leakage, and reduced fibrotic remodeling, which slows progression of kidney disease.