1. Integrated overview of renal ammonia metabolism.
Integrated overview of renal ammonia metabolism. Renal ammoniagenesis occurs primarily in the proximal tubule, involving glutamine uptake by SNAT3 and BoAT-1, glutamine metabolism forming ammonium and bicarbonate, and apical NH4+ secretion involving NHE3 and parallel H+ and NH3 transport. Ammonia reabsorption in the thick ascending limb, involving apical NKCC2-mediated uptake results in medullary ammonia accumulation. Medullary sulfatides (highlighted in green) reversibly bind NH4+, contributing to medullary accumulation. Ammonia is secreted in the collecting duct via parallel H+ and NH3 secretion. The numbers in blue represent the proportion of total excreted ammonia. BoAT-1, apical Na+-dependent neutral amino acid transporter-1; gsc, galactosylceramide backbone; PDG, phosphate-dependent glutaminase.
I. David Weiner et al. CJASN 2015;10:
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