title: Localization of the Na+/H+ exchanger isoform NHE-3 in rabbit and canine kidney.
abstract: The distribution and subcellular localization of Na+/H+ exchanger isoform NHE-3 was studied in rabbit and canine kidney using polyclonal antibodies to an NHE-3 fusion protein. Western blot analyses were performed against microsomal, brush-border, and basolateral membranes isolated from rabbit kidney cortex, outer medulla, and inner medulla. Immunoblots indicated that NHE-3 antibody recognized a strong band with 95-100 kDa molecular mass in cortical microsomes. Subcellular localization studies showed that NHE-3 was expressed in brush-border membranes of kidney cortex. Expression of NHE-3 in the medullary regions was studied by immunoblot analysis of NHE-3 antibody against the microsomal membranes from the outer and inner medulla. NHE-3 antibody specifically labelled a 95-100 kDa protein in outer but not inner medulla. Subcellular localization studies demonstrated that NHE-3 is localized to the brush-border membranes of the outer medulla. Immunoblot analysis against brush-border membranes from canine kidney cortex and outer medulla demonstrated the presence of an 83-90 kDa protein. The above experiments suggest that NHE-3 in rabbit kidney is a 95-100 kDa protein and is expressed in brush-border membranes of the cortex and outer medulla. The canine kidney NHE-3 is a 83-90 kDa protein and is expressed in brush-border membranes of the cortex and outer medulla. Based on its subcellular localization, we conclude that NHE-3 may be involved in vectorial Na+ and HCO3- transport and pHo regulation.
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis 46202-5116.
authors.forename: M
authors.initials: M
authors.lastname: Soleimani
authors.forename: C
authors.initials: C
authors.lastname: Bookstein
authors.forename: G L
authors.initials: GL
authors.lastname: Bizal
authors.forename: M W
authors.initials: MW
authors.lastname: Musch
authors.forename: Y J
authors.initials: YJ
authors.lastname: Hattabaugh
authors.forename: M C
authors.initials: MC
authors.lastname: Rao
authors.forename: E B
authors.initials: EB
authors.lastname: Chang
mesh_terms: D000818:Animals; D004285:Dogs; D015151:Immunoblotting; D007672:Kidney Cortex / Q000737:chemistry* / Q000648:ultrastructure; D007679:Kidney Medulla / Q000737:chemistry; D008297:Male; D008861:Microsomes / Q000737:chemistry; D008871:Microvilli / Q000737:chemistry; D008970:Molecular Weight; D011817:Rabbits; D017923:Sodium-Hydrogen Exchangers / Q000032:analysis* / Q000737:chemistry
chemical_list: D017923:Sodium-Hydrogen Exchangers