title: Human cortical distal nephron: distribution of electrolyte and water transport pathways.
abstract: The exact distributions of the different salt transport systems along the human cortical distal nephron are unknown. Immunohistochemistry was performed on serial cryostat sections of healthy parts of tumor nephrectomized human kidneys to study the distributions in the distal convolution of the thiazide-sensitive Na-Cl cotransporter (NCC), the beta subunit of the amiloride-sensitive epithelial Na channel (ENaC), the vasopressin-sensitive water channel aquaporin 2 (AQP2), and aquaporin 3 (AQP3), the H(+) ATPase, the Na-Ca exchanger (NCX), plasma membrane calcium-ATPase, and calbindin-D28k (CaBP). The entire human distal convolution and the cortical collecting duct (CCD) display calbindin-D28k, although in variable amounts. Approximately 30% of the distal convolution profiles reveal NCC, characterizing the distal convoluted tubule. NCC overlaps with ENaC in a short portion at the end of the distal convoluted tubule. ENaC is displayed all along the connecting tubule (70% of the distal convolution) and the CCD. The major part of the connecting tubule and the CCD coexpress aquaporin 2 with ENaC. Intercalated cells, undetected in the first 20% of the distal convolution, were interspersed among the segment-specific cells of the remainder of the distal convolution, and of the CCD. The basolateral calcium extruding proteins, Na-Ca exchanger (NCX), and the plasma membrane Ca(2+)-ATPase were found all along the distal convolution, and, in contrast to other species, along the CCD, although in varying amounts. The knowledge regarding the precise distribution patterns of transport proteins in the human distal nephron and the knowledge regarding the differences from that in laboratory animals may be helpful for diagnostic purposes and may also help refine the therapeutic management of electrolyte disorders.
authors.affiliation: *Anatomical Department, University of Zurich, Zurich, Switzerland; UMR CNRS 7519, University Louis Pasteur, Strasbourg, France; National Heart, Lung, and Blood Institute, Bethesda, Maryland; and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Helena Lagger
authors.initials: HL
authors.lastname: Biner
authors.affiliation: *Anatomical Department, University of Zurich, Zurich, Switzerland; UMR CNRS 7519, University Louis Pasteur, Strasbourg, France; National Heart, Lung, and Blood Institute, Bethesda, Maryland; and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Arpin-Bott
authors.affiliation: *Anatomical Department, University of Zurich, Zurich, Switzerland; UMR CNRS 7519, University Louis Pasteur, Strasbourg, France; National Heart, Lung, and Blood Institute, Bethesda, Maryland; and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Johannes
authors.initials: J
authors.lastname: Loffing
authors.affiliation: *Anatomical Department, University of Zurich, Zurich, Switzerland; UMR CNRS 7519, University Louis Pasteur, Strasbourg, France; National Heart, Lung, and Blood Institute, Bethesda, Maryland; and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.affiliation: *Anatomical Department, University of Zurich, Zurich, Switzerland; UMR CNRS 7519, University Louis Pasteur, Strasbourg, France; National Heart, Lung, and Blood Institute, Bethesda, Maryland; and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Mark
authors.initials: M
authors.lastname: Knepper
authors.affiliation: *Anatomical Department, University of Zurich, Zurich, Switzerland; UMR CNRS 7519, University Louis Pasteur, Strasbourg, France; National Heart, Lung, and Blood Institute, Bethesda, Maryland; and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Steve C
authors.initials: SC
authors.lastname: Hebert
authors.affiliation: *Anatomical Department, University of Zurich, Zurich, Switzerland; UMR CNRS 7519, University Louis Pasteur, Strasbourg, France; National Heart, Lung, and Blood Institute, Bethesda, Maryland; and Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Kaissling
mesh_terms: D000368:Aged; D001692:Biological Transport; D001834:Body Water / Q000378:metabolism*; D064092:Calbindin 1; D064026:Calbindins; D002352:Carrier Proteins / Q000378:metabolism; D004573:Electrolytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000378:metabolism; D007672:Kidney Cortex; D007685:Kidney Tubules, Collecting / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D009399:Nephrons / Q000378:metabolism*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: C576498:CALB1 protein, human; D064092:Calbindin 1; D064026:Calbindins; D002352:Carrier Proteins; D004573:Electrolytes; D008565:Membrane Proteins; D064030:S100 Calcium Binding Protein G