title: Acid-base transport by the renal distal nephron.
abstract: The functional versatility of the distal nephron is mainly due to the large cytological heterogeneity of the segment. Part of Na+ uptake by distal tubules is dependent on Na+/H+ exchanger 2 (NHE2), implicating a role of distal convoluted cells also in acid-base homeostasis. In addition, intercalated (IC) cells expressed in distal convoluted tubules, connecting tubules and collecting ducts are involved in the final regulation of acid-base excretion. IC cells regulate acid-base handling by 2 main transport proteins, a V-type H+-ATPase and a Cl/HCO3- exchanger, localized at different membrane domains. Type A IC cells are characterized by a luminal H+-ATPase in series with a basolateral Cl/HCO3- exchanger, the anion exchanger AE1. Type B IC cells mediate HCO3- secretion through the apical Cl-/HCO3- exchanger pendrin in series with a H+-ATPase at the basolateral membrane. Alternatively, H+/K+-ATPases have also been found in several distal tubule cells, particularly in type A and B IC cells. All of these mechanisms are finely regulated, and mutations of 1 or more proteins ultimately lead to expressive disorders of acid-base balance.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Luciene R
authors.initials: LR
authors.lastname: Carraro-Lacroix
authors.forename: Gerhard
authors.initials: G
authors.lastname: Malnic
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D000818:Animals; D027963:Chloride-Bicarbonate Antiporters / Q000502:physiology; D017506:H(+)-K(+)-Exchanging ATPase / Q000502:physiology; D006801:Humans; D017136:Ion Transport; D007686:Kidney Tubules, Distal / Q000378:metabolism*; D009399:Nephrons / Q000378:metabolism*; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology; D025262:Vacuolar Proton-Translocating ATPases / Q000502:physiology
chemical_list: D027963:Chloride-Bicarbonate Antiporters; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D025262:Vacuolar Proton-Translocating ATPases; D017506:H(+)-K(+)-Exchanging ATPase