Biomaterial Database

Expression of Na+/H+ exchanger isoforms in inner segment of inner medullary collecting duct. 1998

A M Sun, and Y Liu, and J Centracchio, and L D Dworkin

Division of Renal Diseases, Rhode Island Hospital, Brown University School of Medicine, Providence, Rhode Island 02903, USA.

Na+/H+ exchangers (NHE) play a critical role in many cellular and transport processes in the inner medullary collecting duct (IMCD). Morphologically, the IMCD is divided into the outer (IMCD1), middle (IMCD2), and inner (IMCD3) segments. The inner, IMCD3 segment contains only one cell type, the IMCD cell, which is distinct in ultrastructure and in function from the principal and intercalated cells that are present in other portions of the IMCD. NHEs constitute a gene family containing several isoforms (NHE1, NHE2, NHE3, NHE4 and NHE5) which possess distinct characteristics and serve specialized functions. To understand the molecular basis of NHE-related processes in the IMCD, it is critical to know the molecular identity of the NHEs in this tubule segment. The purpose of the present study was to identify the NHE isoforms present and their polar distribution in IMCD3. Applying the reverse transcription-polymerase chain reaction (RT-PCR) technique to IMCD3 (obtained from distal 50% of inner medulla) of mouse and rat kidneys, we found that NHE1, NHE2 and NHE4, but not NHE3 were expressed in both species. The polar localization of NHE in IMCD3 was examined in tubules isolated from rats and perfused in vitro with HEPES-buffered solutions under isotonic conditions. pHi was measured by BCECF fluorescence. Na+-dependent, amiloride-inhibitable pHi recovery from cell acidification (consistent with NHE) was detected in the basolateral, but not the apical, membrane of IMCD3. We conclude that NHE1, NHE2 and NHE4, but not NHE3, are present in both the mouse and rat IMCD3. Functionally, NHE is limited to the basolateral membrane. Additional studies are needed to determine the physiological roles and regulation of basolateral NHE isoforms in this tubule segment.

UI	MeSH Term	Description	Entries
D007679	Kidney Medulla	The internal portion of the kidney, consisting of striated conical masses, the renal pyramids, whose bases are adjacent to the cortex and whose apices form prominent papillae projecting into the lumen of the minor calyces.	Kidney Papilla,Kidney Medullas,Kidney Papillas,Medulla, Kidney,Medullas, Kidney,Papilla, Kidney,Papillas, Kidney
D007685	Kidney Tubules, Collecting	Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of Bellini) which opens on the summit of the papilla.	Kidney Collecting Ducts,Kidney Collecting Duct,Collecting Duct, Kidney,Collecting Ducts, Kidney
D008297	Male		Males
D004232	Diuretics	Agents that promote the excretion of urine through their effects on kidney function.	Diuretic,Diuretic Effect,Diuretic Effects,Effect, Diuretic,Effects, Diuretic
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000584	Amiloride	A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)	Amidal,Amiduret Trom,Amiloberag,Amiloride Hydrochloride,Amiloride Hydrochloride, Anhydrous,Kaluril,Midamor,Midoride,Modamide,Anhydrous Amiloride Hydrochloride,Hydrochloride, Amiloride,Hydrochloride, Anhydrous Amiloride,Trom, Amiduret
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012333	RNA, Messenger	RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.	Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated
D015870	Gene Expression	The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.	Expression, Gene,Expressions, Gene,Gene Expressions
D016133	Polymerase Chain Reaction	In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.	Anchored PCR,Inverse PCR,Nested PCR,PCR,Anchored Polymerase Chain Reaction,Inverse Polymerase Chain Reaction,Nested Polymerase Chain Reaction,PCR, Anchored,PCR, Inverse,PCR, Nested,Polymerase Chain Reactions,Reaction, Polymerase Chain,Reactions, Polymerase Chain