Ouabain stimulates Na-K-ATPase through a sodium/hydrogen exchanger-1 (NHE-1)-dependent mechanism in human kidney proximal tubule cells

Kristine A. Holthouser, Amritlal Mandal, Michael L. Merchant, Jeffrey R. Schelling, Nicholas A Delamere, Ronald R. Valdes, Suresh C. Tyagi, Eleanor D. Lederer, Syed J. Khundmiri

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Abstract

Recent investigations demonstrate increased Na/H exchanger-1 (NHE-1) activity and plasma levels of ouabain-like factor in spontaneously hypertensive rats. At nanomolar concentrations, ouabain increases Na-K-ATPase activity, induces cell proliferation, and activates complex signaling cascades. We hypothesize that the activity of NHE-1 and Na-K-ATPase are interdependent. To test whether treatment with picomolar ouabain regulates Na-K-ATPase through an NHE-1-dependent mechanism, we examined the role of NHE-1 in ouabain-mediated stimulation of Na-K-ATPase in kidney proximal tubule cell lines [opossum kidney (OK), HK-2, HKC-5, and HKC-11] and rat kidney basolateral membranes. Ouabain stimulated Na-K-ATPase activity and tyrosine phosphorylation in cells that express NHE-1 (OK, HKC-5, and HKC-11) but not in HK-2 cells that express very low levels of NHE-1. Inhibition of NHE-1 with 5 μM EIPA, a NHE-1-specific inhibitor, prevented ouabain-mediated stimulation of 86Rb uptake and Na-K-ATPase phosphorylation in OK, HKC-5, and HKC-11 cells. Expression of wild-type NHE-1 in HK2 cells restored regulation of Na-K-ATPase by picomolar ouabain. Treatment with picomolar ouabain increased membrane expression of Na-K-ATPase and enhanced NHE-1-Na-K-ATPase α1-subunit association. Treatment with ouabain (1 μg·kg body wt-1·day -1) increased Na-KATPase activity, expression, phosphorylation, and association with NHE-1 increased in rat kidney cortical basolateral membranes. Eight days' treatment with ouabain (1 μg·kg body wt -1·day-1) resulted in increased blood pressure in these rats. These results suggest that the association of NHE-1 with Na-K-ATPase is critical for ouabain-mediated regulation of Na-K-ATPase and that these effects may play a role in cardioglycoside-stimulated hypertension.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Physiology
Volume299
Issue number1
DOIs
StatePublished - Jul 2010

Fingerprint

Proximal Kidney Tubule
Sodium-Hydrogen Antiporter
Ouabain
Opossums
Kidney
Phosphorylation
Membranes
sodium-translocating ATPase
Inbred SHR Rats
Tyrosine

Keywords

  • Cardioglycosides
  • Phosphorylation

ASJC Scopus subject areas

  • Physiology
  • Urology

Cite this

Ouabain stimulates Na-K-ATPase through a sodium/hydrogen exchanger-1 (NHE-1)-dependent mechanism in human kidney proximal tubule cells. / Holthouser, Kristine A.; Mandal, Amritlal; Merchant, Michael L.; Schelling, Jeffrey R.; Delamere, Nicholas A; Valdes, Ronald R.; Tyagi, Suresh C.; Lederer, Eleanor D.; Khundmiri, Syed J.

In: American Journal of Physiology - Renal Physiology, Vol. 299, No. 1, 07.2010.

Research output: Contribution to journalArticle

Holthouser, Kristine A. ; Mandal, Amritlal ; Merchant, Michael L. ; Schelling, Jeffrey R. ; Delamere, Nicholas A ; Valdes, Ronald R. ; Tyagi, Suresh C. ; Lederer, Eleanor D. ; Khundmiri, Syed J. / Ouabain stimulates Na-K-ATPase through a sodium/hydrogen exchanger-1 (NHE-1)-dependent mechanism in human kidney proximal tubule cells. In: American Journal of Physiology - Renal Physiology. 2010 ; Vol. 299, No. 1.
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