Na+/H+ exchanger isoforms NHE-2 and NHE-1 in inner medullary collecting duct cells

Expression, functional localization, and differential regulation

Manoocher Soleimani, Gurinder Singh, Gwen L. Bizal, Steven R. Gullans, James A. McAteerll

Research output: Contribution to journalArticle

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Abstract

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. Acid-stimulated, dimethyl amiloride-sensitive 22Na+ uptake and sodium-dependent pHi recovery occurred only from the basolateral surface of the cells, indicating localization of Na+/H+ exchanger to the basolateral membrane domain. Incubation of IMCD cells in high osmolality media (510 mosm/liter) for 72 h stimulated the Na+/H+ exchanger activity by 59% (p < 0.001). NHE-1 mRNA abundance decreased, whereas NHE-2 mRNA increased in high osmolality media. Incubation of IMCD cells in acid media (pH 7.1) for 48 h did not affect the Na+/H+ exchanger activity compared with control (pH 7.4) (p > 0.05). Northern hybridization, however, indicated that NHE-1 mRNA increased, whereas NHE-2 mRNA decreased in acid media. In conclusion, mIMCD-3 cells express NHE-1 and NHE-2 mRNAs. The cell functional studies in mIMCD-3 cells strongly suggest that NHE-2, along with NHE-1, is expressed in the basolateral membrane domain. They further demonstrate differential regulation of NHE-1 and NHE-2 mRNAs in response to acidosis and high osmolality and suggest that NHE-2 may be involved in volume regulation of IMCD cells.

Original languageEnglish
Pages (from-to)27973-27978
Number of pages6
JournalJournal of Biological Chemistry
Volume269
Issue number45
StatePublished - Nov 11 1994

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Sodium-Hydrogen Antiporter
Ducts
Protein Isoforms
Messenger RNA
Membranes
Acids
Amiloride
Cloning
Osmolar Concentration
Kidney
Sodium
Recovery
Acidosis
Organism Cloning
Experiments

ASJC Scopus subject areas

  • Biochemistry

Cite this

Na+/H+ exchanger isoforms NHE-2 and NHE-1 in inner medullary collecting duct cells : Expression, functional localization, and differential regulation. / Soleimani, Manoocher; Singh, Gurinder; Bizal, Gwen L.; Gullans, Steven R.; McAteerll, James A.

In: Journal of Biological Chemistry, Vol. 269, No. 45, 11.11.1994, p. 27973-27978.

Research output: Contribution to journalArticle

Soleimani, Manoocher ; Singh, Gurinder ; Bizal, Gwen L. ; Gullans, Steven R. ; McAteerll, James A. / Na+/H+ exchanger isoforms NHE-2 and NHE-1 in inner medullary collecting duct cells : Expression, functional localization, and differential regulation. In: Journal of Biological Chemistry. 1994 ; Vol. 269, No. 45. pp. 27973-27978.
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abstract = "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. Acid-stimulated, dimethyl amiloride-sensitive 22Na+ uptake and sodium-dependent pHi recovery occurred only from the basolateral surface of the cells, indicating localization of Na+/H+ exchanger to the basolateral membrane domain. Incubation of IMCD cells in high osmolality media (510 mosm/liter) for 72 h stimulated the Na+/H+ exchanger activity by 59{\%} (p < 0.001). NHE-1 mRNA abundance decreased, whereas NHE-2 mRNA increased in high osmolality media. Incubation of IMCD cells in acid media (pH 7.1) for 48 h did not affect the Na+/H+ exchanger activity compared with control (pH 7.4) (p > 0.05). Northern hybridization, however, indicated that NHE-1 mRNA increased, whereas NHE-2 mRNA decreased in acid media. In conclusion, mIMCD-3 cells express NHE-1 and NHE-2 mRNAs. The cell functional studies in mIMCD-3 cells strongly suggest that NHE-2, along with NHE-1, is expressed in the basolateral membrane domain. They further demonstrate differential regulation of NHE-1 and NHE-2 mRNAs in response to acidosis and high osmolality and suggest that NHE-2 may be involved in volume regulation of IMCD cells.",
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