Functional identity of a purified proximal tubule anion exchanger protein: mediation of chloride/formate and chloride/bicarbonate exchange.

Based on the transport activities and inhibitor sensitivities, different functional modes of anion exchangers have been identified in the kidney proximal tubule including chloride/formate, chloride/oxalate, chloride/hydroxyl, and chloride/bicarbonate exchange. There is little information on the molecular structure and properties of the protein(s) involved in these processes. Previously, using stilbene affinity matrix and Pac Q chromatography, we partially purified a protein with anion exchange properties in brush border membranes (BBM) isolated from rabbit kidney proximal tubules.

Glycosylation of the Na+/H+ exchanger isoform NHE-3 is species specific.

The glycosylation of Na+/H+ exchanger isoform NHE-3 was studied in brush border membrane (BBM) vesicles isolated from rabbit, dog, and rat kidney cortex. Western blot analyses were performed against BBM proteins by using polyclonal antibodies to an NHE-3 fusion protein. In rabbit kidney, NHE-3 antibody recognized a band with approximately 95 kd molecular mass.

Na+/H+ exchanger isoforms NHE-2 and NHE-1 in inner medullary collecting duct cells. Expression, functional localization, and differential regulation.

Recent cloning experiments have identified the existance of four distinct Na+/H+ exchanger isoforms designated as NHE-1, NHE-2, NHE-3, and NHE-4. The cellular distribution, subcellular localization, and regulation of one of these isoforms, NHE-2, in the kidney remains unknown. Northern hybridization showed that NHE-2, along with NHE-1, is expressed in cultured renal medullary collecting duct (mIMCD-3) cells.

Localization of the Na+/H+ exchanger isoform NHE-3 in rabbit and canine kidney.

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.

Acute regulation of Na+/H+ exchange, Na+:HCO3- cotransport, and C1-/base exchange in acid base disorders.

The aim of these experiments was to study acute regulation of proximal tubule H+/HCO3- transport systems in acid-base disorders. Proximal tubular suspensions were prepared from rabbit kidney cortex and incubated in acidic (pH 6.9), control (pH 7.