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Na/K-ATPase endocytosis couples pumping and leaking activities in renal epithelial cells: a hypothesis

Jiang Liu1

  • 1Department of Medicine, College of Medicine, University of Toledo, Toledo, Ohio 43614, USA. jiang.liu@utoledo.edu

Cellular and Molecular Biology (Noisy-Le-Grand, France)
|May 31, 2007
PubMed

Insights

Cardiotonic steroids (CTS), like ouabain, reduce kidney proximal tubule sodium transport by internalizing Na/K-ATPase. This adaptation is crucial for managing body fluid balance.

Area of Science:

  • Nephrology
  • Molecular Biology
  • Physiology

Background:

  • Renal adaptation to volume expansion and sodium intake involves decreased proximal tubule sodium transport.
  • The molecular mechanisms underlying this transport alteration remain largely unknown.

Purpose of the Study:

  • To investigate the role of cardiotonic steroids (CTS) in renal proximal tubule sodium transport regulation.
  • To elucidate the molecular mechanisms by which CTS affect Na/K-ATPase and NHE3 in renal cells.

Main Methods:

  • Utilized LLC-PK1 cells to study the effects of low ouabain concentration on transepithelial Na+ transport.
  • Investigated changes in intracellular Na+ concentration ([Na+]i) and Na/K-ATPase localization.
  • Examined the impact on apical NHE3 expression and activity.

Main Results:

  • Low ouabain concentrations inhibited transepithelial Na+ transport without altering intracellular Na+ concentration.
  • Ouabain-activated signaling pathways led to basolateral Na/K-ATPase endocytosis.
  • Apical NHE3 was down-regulated in response to ouabain treatment.

Conclusions:

  • Cardiotonic steroids (CTS), including ouabain and marinobufagenin (MBG), are implicated in renal proximal tubule adaptation to volume expansion.
  • CTS-induced Na/K-ATPase endocytosis may link pumping and leaking functions in renal epithelial cells.

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