TY - JOUR
T1 - Luminal Na+/H+ exchange in the proximal tubule
AU - Bobulescu, I. Alexandru
AU - Moe, Orson W.
N1 - Funding Information:
We thank Dr. Michel Baum for helpful and insightful discussions. The authors were supported by the National Institutes of Health (R01-DK-48482 and P01-DK-020543 to O.W.M.), the Simmons Family Foundation (O.W.M.), the Charles and Jane Pak Center for Mineral Metabolism and Clinical Research (fellowship grant to I.A.B.), and by the American Society of Nephrology (Carl W. Gottschalk Research Scholar Award to I.A.B.).
PY - 2009/5
Y1 - 2009/5
N2 - The proximal tubule is critical for whole-organism volume and acid-base homeostasis by reabsorbing filtered water, NaCl, bicarbonate, and citrate, as well as by excreting acid in the form of hydrogen and ammonium ions and producing new bicarbonate in the process. Filtered organic solutes such as amino acids, oligopeptides, and proteins are also retrieved by the proximal tubule. Luminal membrane Na+/H+ exchangers either directly mediate or indirectly contribute to each of these processes. Na+/H + exchangers are a family of secondary active transporters with diverse tissue and subcellular distributions. Two isoforms, NHE3 and NHE8, are expressed at the luminal membrane of the proximal tubule. NHE3 is the prevalent isoform in adults, is the most extensively studied, and is tightly regulated by a large number of agonists and physiological conditions acting via partially defined molecular mechanisms. Comparatively little is known about NHE8, which is highly expressed at the lumen of the neonatal proximal tubule and is mostly intracellular in adults. This article discusses the physiology of proximal Na+/H+ exchange, the multiple mechanisms of NHE3 regulation, and the reciprocal relationship between NHE3 and NHE8 at the lumen of the proximal tubule.
AB - The proximal tubule is critical for whole-organism volume and acid-base homeostasis by reabsorbing filtered water, NaCl, bicarbonate, and citrate, as well as by excreting acid in the form of hydrogen and ammonium ions and producing new bicarbonate in the process. Filtered organic solutes such as amino acids, oligopeptides, and proteins are also retrieved by the proximal tubule. Luminal membrane Na+/H+ exchangers either directly mediate or indirectly contribute to each of these processes. Na+/H + exchangers are a family of secondary active transporters with diverse tissue and subcellular distributions. Two isoforms, NHE3 and NHE8, are expressed at the luminal membrane of the proximal tubule. NHE3 is the prevalent isoform in adults, is the most extensively studied, and is tightly regulated by a large number of agonists and physiological conditions acting via partially defined molecular mechanisms. Comparatively little is known about NHE8, which is highly expressed at the lumen of the neonatal proximal tubule and is mostly intracellular in adults. This article discusses the physiology of proximal Na+/H+ exchange, the multiple mechanisms of NHE3 regulation, and the reciprocal relationship between NHE3 and NHE8 at the lumen of the proximal tubule.
KW - Acid-based balance
KW - Bicarbonate transport
KW - Chloride transport
KW - Sodium transport
KW - Sodium-hydrogen exchange
KW - Sodium-proton exchange
KW - Volume regulation
KW - pH regulation
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U2 - 10.1007/s00424-008-0595-1
DO - 10.1007/s00424-008-0595-1
M3 - Article
C2 - 18853182
AN - SCOPUS:64149086865
SN - 0031-6768
VL - 458
SP - 5
EP - 21
JO - Pflugers Archiv European Journal of Physiology
JF - Pflugers Archiv European Journal of Physiology
IS - 1
ER -