title: Localization of epithelial sodium channel and aquaporin-2 in rabbit kidney cortex.
abstract: The amiloride-sensitive epithelial sodium channel (ENaC) and the vasopressin-dependent water channel aquaporin-2 (AQP2) mediate mineralocorticoid-regulated sodium- and vasopressin-regulated water reabsorption, respectively. Distributions of ENaC and AQP2 have been shown by immunohistochemistry in rats. Functional data from rabbits suggest a different distribution pattern of these channels than in rats. We studied, by immunohistochemistry in the rabbit kidney cortex, the distributions of ENaC and AQP2, in conjunction with marker proteins for distal segments. In rabbit cortex ENaC is restricted to the connecting tubule (CNT) cells and cortical collecting duct (CCD) cells. The intracellular distribution of ENaC shifts from the apical membrane in the most upstream CNT cells to a cytoplasmic location further downstream in the CNT and in the CCD cells. AQP2 is detected in the CCD cells exclusively. The anatomic subdivisions in the rabbit distal nephron coincide exactly with distributions of apical transport systems. The differences between rabbits and rats in the distribution patterns of ENaC and AQP2 may explain functional differences in renal salt and water handling between these species.
authors.affiliation: Institute of Anatomy, University of Zurich, CH-8057 Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Loffing
authors.forename: D
authors.initials: D
authors.lastname: Loffing-Cueni
authors.forename: A
authors.initials: A
authors.lastname: Macher
authors.forename: S C
authors.initials: SC
authors.lastname: Hebert
authors.forename: B
authors.initials: B
authors.lastname: Olson
authors.forename: M A
authors.initials: MA
authors.lastname: Knepper
authors.forename: B C
authors.initials: BC
authors.lastname: Rossier
authors.forename: B
authors.initials: B
authors.lastname: Kaissling
mesh_terms: D000818:Animals; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000378:metabolism*; D001581:Benzothiadiazines; D002034:Bumetanide / Q000494:pharmacology; D064026:Calbindins; D002352:Carrier Proteins / Q000187:drug effects* / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology; D053503:Epithelial Sodium Channels; D005260:Female; D007672:Kidney Cortex / Q000033:anatomy & histology / Q000378:metabolism*; D008297:Male; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D015222:Sodium Channels / Q000378:metabolism*; D049993:Sodium Chloride Symporter Inhibitors / Q000494:pharmacology; D028021:Sodium-Potassium-Chloride Symporters; D014018:Tissue Distribution
chemical_list: C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D001581:Benzothiadiazines; D064026:Calbindins; D002352:Carrier Proteins; D004232:Diuretics; D053503:Epithelial Sodium Channels; D064030:S100 Calcium Binding Protein G; D015222:Sodium Channels; D049993:Sodium Chloride Symporter Inhibitors; D028021:Sodium-Potassium-Chloride Symporters; D002034:Bumetanide; D006180:Proton-Translocating ATPases