Characterization of Na+/H+ Exchange Activity in Cultured Rat Hippocampal Astrocytes

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)191-198
Journal / PublicationJournal of Neuroscience Research
Issue number2
Publication statusPublished - 15 Apr 1996
Externally publishedYes


Astrocytes actively maintain their intracellular pH (pHi) more alkaline than expected by passive distribution of H+. Acid extruding transporters such as the amiloride-sensitive Na+/H+ exchanger (NHE) are necessary for pH regulation. Currently, four mammalian NHEs (NHE1-NHE4) have been cloned, with a fifth (NHE5) partially cloned. We attempted to determine which isoform(s) of NHE was present in cultured hippocampal astrocytes using amiloride sensitivity and immunospecificity as criteria. In the absence of HCO3-, amiloride blocked pH(i) recovery after an acid load with an IC50 of ~3.18 μM, similar to values reported for the amiloride-sensitive isoforms NHE1 and NHE2. Immunoblotting with a highly specific antibody for NHE1 identified a 100 kDa protein, indicating the presence of NHE1 in whole brain, hippocampus, and cultured hippocampal astrocytes. Further probing for an additional amiloride-sensitive NHE failed to detect evidence of the presence of NHE4. Surprisingly, application of the potent analog of amiloride, ethylisopropylamiloride (EIPA), caused a reversible alkalinization of PH(i), suggesting the presence of an additional acid/base transport mechanism that is EIPA-sensitive.

Research Area(s)

  • amiloride, antibody, BCECF, EIPA, glia, Na+/H+ exchanger, Western blot

Citation Format(s)