Plasmalemmal V-H+-ATPases regulate intracellular pH in human lung microvascular endothelial cells

José D. Rojas, Souad R. Sennoune, Debasish Maiti, Gloria M. Martínez, Karina Bakunts, Donald E. Wesson, Raul Martínez-Zaguilán

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

The lung endothelium layer is exposed to continuous CO2 transit which exposes the endothelium to a substantial acid load that could be detrimental to cell function. The Na+/H+ exchanger and HCO3--dependent H+-transporting mechanisms regulate intracellular pH (pHcyt) in most cells. Cells that cope with high acid loads might require additional primary energy-dependent mechanisms. V-H+-ATPases localized at the plasma membranes (pmV-ATPases) have emerged as a novel pH regulatory system. We hypothesized that human lung microvascular endothelial (HLMVE) cells use pmV-ATPases, in addition to Na +/H+ exchanger and HCO3--based H+-transporting mechanisms, to maintain pHcyt homeostasis. Immunocytochemical studies revealed V-H+-ATPase at the plasma membrane, in addition to the predicted distribution in vacuolar compartments. Acid-loaded HLMVE cells exhibited proton fluxes in the absence of Na+ and HCO3- that were similar to those observed in the presence of either Na+, or Na+ and HCO3 -. The Na+- and HCO3--independent pHcyt recovery was inhibited by bafilomycin A1, a V-H +-ATPase inhibitor. These studies show a Na+- and HCO 3--independent pHcyt regulatory mechanism in HLMVE cells that is mediated by pmV-ATPases.

Original languageEnglish (US)
Pages (from-to)1123-1132
Number of pages10
JournalBiochemical and Biophysical Research Communications
Volume320
Issue number4
DOIs
StatePublished - Aug 6 2004
Externally publishedYes

Keywords

  • Capillary endothelium
  • Fluorescence spectroscopy
  • Immunocytochemistry
  • Intracellular pH
  • Proton pumps

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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