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Updated: May 19, 2026

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane
07:38

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

Published on: March 30, 2015

Na+,K+-ATPase functionally interacts with the plasma membrane Na+,Ca2+ exchanger to prevent Ca2+ overload and

Dmitry A Sibarov1, Artemiy E Bolshakov, Polina A Abushik

  • 1Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.

The Journal of Pharmacology and Experimental Therapeutics
|August 29, 2012
PubMed

Insights

Ouabain prevents neuron death from excitotoxicity by enhancing calcium extrusion via the sodium-calcium exchanger. This neuroprotective effect, independent of Na(+),K(+)-ATPase pump activity, suggests a novel role for this pathway in brain cell survival.

Area of Science:

  • Neuroscience
  • Cell Biology
  • Pharmacology

Background:

  • Excitotoxicity, triggered by glutamate receptor agonists like NMDA and kainate, is a major cause of neuronal apoptosis.
  • Intracellular calcium (Ca2+) overload and altered synaptic activity are key mediators of excitotoxic neuronal injury.
  • The Na(+),K(+)-ATPase, a critical ion pump, has a binding site for ouabain, a cardiac glycoside.

Purpose of the Study:

  • To investigate the neuroprotective effects of ouabain against glutamate receptor agonist-induced apoptosis in cultured rat cortical neurons.
  • To elucidate the mechanisms underlying ouabain's potential anti-apoptotic actions, particularly its role in calcium homeostasis and synaptic activity.
  • To explore the potential involvement of the Na(+),K(+)-ATPase and Na(+)-Ca(2+) exchanger in ouabain's neuroprotective effects.

Main Methods:

  • Fluorescent viability assays to quantify neuronal survival.
  • Immunocytochemistry to assess the expression of the anti-apoptotic protein Bcl-2.
  • Patch-clamp recordings and Ca(2+) imaging to analyze synaptic activity and intracellular calcium levels.
  • Pharmacological inhibition of the Na(+)-Ca(2+) exchanger using KB-R7943.

Main Results:

  • Ouabain (0.1-1 nM) completely prevented NMDA- or kainate-induced apoptosis in cultured rat cortical neurons.
  • Ouabain treatment maintained neuronal survival and Bcl-2 expression levels comparable to control conditions.
  • Subnanomolar ouabain concentrations inhibited NMDA/kainate-induced increases in excitatory postsynaptic current frequency and intracellular Ca(2+) overload.
  • Ouabain's neuroprotective effects were abolished by inhibiting the Na(+)-Ca(2+) exchanger, indicating its crucial role.

Conclusions:

  • Ouabain confers significant neuroprotection against excitotoxicity by accelerating Ca(2+) extrusion via the Na(+)-Ca(2+) exchanger.
  • This anti-apoptotic mechanism is independent of the Na(+),K(+)-ATPase's ion transport function.
  • The findings suggest a novel neuroprotective role for the Na(+),K(+)-ATPase system, activated by endogenous ouabain-like compounds, in preventing neuronal death.

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