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Research Article Free access | 10.1172/JCI119128

Chronic metabolic acidosis enhances NHE-3 protein abundance and transport activity in the rat thick ascending limb by increasing NHE-3 mRNA.

K Laghmani, P Borensztein, P Ambühl, M Froissart, M Bichara, O W Moe, R J Alpern, and M Paillard

Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Institut National de la Santé et de la Recherche Médicale U.356, Université Pierre et Marie Curie, Centre Hospitalo-Universitaire Broussais, Paris, France.

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Published January 1, 1997 - More info

Published in Volume 99, Issue 1 on January 1, 1997
J Clin Invest. 1997;99(1):24–30. https://doi.org/10.1172/JCI119128.
© 1997 The American Society for Clinical Investigation
Published January 1, 1997 - Version history
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Abstract

Chronic metabolic acidosis (CMA) is associated with an adaptive increase in the bicarbonate absorptive capacity of the rat medullary thick ascending limb (MTAL). To specify whether NHE-3, the apical MTAL Na/H exchanger, is involved in this adaptation, NHE-3 mRNA was quantified by a competitive RT-PCR using an internal standard which differed from the wild-type NHE-3 mRNA by an 80-bp deletion. CMA increased NHE-3 mRNA from 0.025+/-0.003 to 0.042+/-0.009 amol/ng total RNA (P < 0.005). NHE-3 transport activity was measured as the initial proton flux rate calculated from the Na-dependent cell pH recovery of Na-depleted acidified MTAL cells in the presence of 50 microM HOE694 which specifically blocks NHE-1, the basolateral MTAL NHE isoform. CMA caused a 68% increase in NHE-3 transport activity (P < 0.001). In addition, CMA was associated with a 71% increase in NHE-3 protein abundance (P < 0.05) as determined by Western blot analysis on MTAL membranes using a polyclonal antiserum directed against a cytoplasmic epitope of rat NHE-3. Thus, NHE-3 adapts to CMA in the rat MTAL via an increase in the mRNA transcript that enhances NHE-3 protein abundance and transport activity.

Version history
  • Version 1 (January 1, 1997): No description
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