What is the role of glomerular capillaries in the pathophysiology of proteinuria?

Updated: Mar 25, 2020
  • Author: Beje Thomas, MD; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Glomerular capillaries are internally lined by endothelial cells that are in contact with the bloodstream. A unique feature of glomerular endothelial cells is their fenestrations—holes in the cell that permit passage of fluid across the glomerular capillary wall. Although these fenestrations are much larger than albumin, the endothelial surface has a covering coat made up of negatively charged glycocalyx, glycosaminoglycans and proteoglycans that retards the positively charged albumin and other plasma proteins. This cellular coat acts as both a size- and charge-based barrier. In addition, endothelium activation and loss of selectivity leads to prolonged exposure of podocytes to proteins. This results in the activation of renin-angiotensin in podocytes [6] and alteration of size selectivity. Damage to podocytes in turns leads to decrease in vascular endothelial growth factor (VEGF) required for endothelial fenestrae formation [7]


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