Why does captopril cause proteinuria? ACE inhibitors prevent the formation of Angiotensin II, which will prevent efferent arteriole constriction, which will decrease the GFR, which ultimately decreases the filtration of proteins. Any explanations would be greatly appreciated. I also read on eMedicine that captopril is used as a treatment of proteinuria.

http://www.emedicine.com/med/topic1611.htm


Under "ACE inhibitors listed as a treatment for proteinuria" :confused:


Thanks

Captopril can worsen kindey function in cases of chronic renal failure and renal artery stenosis. This occurs because ACE inhibitors interfere with prostaglandin and NO synthesis by endothelial cells. I suppose the resulting hypoperfusion can lead to proteinuria

I second that. They contraindicated in patients with BILATERAL renal artery stenosis.

Why does captopril cause proteinuria? ACE inhibitors prevent the formation of Angiotensin II, which will prevent efferent arteriole constriction, which will decrease the GFR, which ultimately decreases the filtration of proteins. Any explanations would be greatly appreciated. I also read on eMedicine that captopril is used as a treatment of proteinuria.

http://www.emedicine.com/med/topic1611.htm


Under "ACE inhibitors listed as a treatment for proteinuria" :confused:


Thanks

My thought on it....use of ACEI would increase BK; this would give you cough and potentiated vasodilation. The glomeruli are vessels also, and are fenestrated no doubt. If BK would to vasodilate already leaky vessels, you may get a proteins being filtered into your urine.

just a thought

ucb

My thought on it....use of ACEI would increase BK; this would give you cough and potentiated vasodilation. The glomeruli are vessels also, and are fenestrated no doubt. If BK would to vasodilate already leaky vessels, you may get a proteins being filtered into your urine.

just a thought

ucb

cool, thanks for your perspective.

ACE's are notorious for causing renal failure, pure and simple.

The dichotomy is that ACE's are given to prevent renal failure in diabetics.

blocking AT II increases renal blood flow and GFR (using ARB's or ACE's). This can cause damage to the nephrons and result in proteinuria (another way to look at it)...I dont think vessels can be dilated or leaky enough to leak protein, without being damaged, so Im not sure that BK has a link here. In healthy kidneys, ACE's are fine, and in diabetics, it is worth the tradeoff. Someone with a GFR of 35, however, probably should not be on an ACE. Just my take on it.

blocking AT II increases renal blood flow and GFR (using ARB's or ACE's). .

So, you're saying the increased effect of Q >> than the vasodilation, which is why there is an increased GFR? Losing the vc independently obviously decreases the pressure-->decrs GFR.

Efferent resistance is decreased via blockage of AT II. This is the mechanism by which you increase GFR while not increasing perfusion pressure necessarily. I understand that this may seem counterintuitive, but I believe the correction by the afferent limb comes after this and this allows for greater perfusion.

This is also why, when you have renal artery stenosis, and the afferent arterioles are maximally dilated, you are relying on that efferent limb to provide you with resistance to filter the plasma. When you knock it out (via ACE/ARB) you essentially open the valve and eliminate any glomerular pressure that was filtering...it just rushes through. (Im sure you all knew that).

Im not sure if this is what you are saying or not. I personally dont think the proteinuria comes from 'leakiness' I think it comes from actual kidney damage, which may only be noticeable in someone with poor kidney function anyway.

All interesting points. thanks