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Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles
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Na(+)-H+ exchange in resident alveolar macrophages: activation by osmotic cell shrinkage

T A Heming1, A Bidani

  • 1Department of Internal Medicine & Physiology, University of Texas Medical Branch, Galveston 77555-0561, USA.

Journal of Leukocyte Biology
|April 1, 1995
PubMed

Insights

Resident alveolar macrophages use the sodium-hydrogen exchanger (NHE) to regulate intracellular pH (pHi) during osmotic cell shrinkage. This finding suggests the NHE plays a role in the cell volume regulatory response.

Area of Science:

  • Cellular Physiology
  • Macrophage Biology
  • Ion Transport

Background:

  • Intracellular pH (pHi) homeostasis in alveolar macrophages is mainly regulated by H(+)-ATPase.
  • The Na(+)-H+ exchanger (NHE) has a limited role in pHi regulation under physiological conditions.

Purpose of the Study:

  • To investigate the physiological significance of the NHE in resident alveolar macrophages.
  • To determine the role of NHE in pHi regulation under hyperosmotic conditions.

Main Methods:

  • Resident rabbit alveolar macrophages were subjected to hyperosmotic challenges.
  • Intracellular pH (pHi) and Na(+)-H+ exchanger activity were measured.
  • Amiloride sensitivity was assessed.

Main Results:

  • Hyperosmotic stress induced cell shrinkage and an amiloride-sensitive increase in baseline pHi.
  • NHE-mediated pHi recovery from acid loads was enhanced under hyperosmotic conditions.
  • Cell shrinkage shifted the NHE's pHi set point without affecting extracellular Na+ affinity.

Conclusions:

  • Na(+)-H+ exchange in alveolar macrophages is activated by osmotic cell shrinkage.
  • The NHE may be involved in the volume regulatory response of these cells.

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