Studies on H+-ATPase in cultured rabbit nonpigmented ciliary epithelium

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Studies were conducted to examine the influence of the H+-ATPase inhibitor bafilomycin A1 on cultured rabbit nonpigmented ciliary epithelial cells (NPE). Cytoplasmic pH and sodium concentrations were measured by digital fluorescence microscopy using BCECF and SBFI respectively. In some experiments, cell sodium content was measured by atomic absorption spectroscopy. Added alone, bafilomycin A1 (100 nM) failed to change cytoplasmic pH but it caused an increase of cytoplasmic sodium concentration which occurred within 10 min. It is likely that the rise of cytoplasmic sodium concentration was responsible for the stimulation of active sodium- potassium transport which occurred in bafilomycin A1-treated cells as judged by a 50% increase of ouabain sensitive potassium (86Rb) uptake. In bafilomycin A1-treated cells, but not in control cells, dimethylamiloride (DMA) inhibited ouabain-sensitive potassium (86Rb) uptake in a dose- dependent manner with an IC50 of ~2 μM. DMA (10 μM) also prevented the increase of cytoplasmic sodium caused by bafilomycin A1. Added alone, DMA (10 μM) failed to change cytoplasmic sodium content but reduced cytoplasmic pH by ~0.4 pH units. In cells that first received 10μM DMA, the subsequent addition of bafilomycin A1 (100 nM) caused a further cytoplasmic pH reduction of ~0.3 pH units. Taken together, the results suggest H+-ATPase might contribute to the regulation of basal cytoplasmic pH in cultured NPE. In the presence of bafilomycin A1, Na-H exchanger activity appears to be stimulated, so stabilizing cytoplasmic pH but resulting in an increase of cytoplasmic sodium concentration and consequent stimulation of active sodium- potassium transport.

Original languageEnglish (US)
Pages (from-to)67-72
Number of pages6
JournalThe Journal of Membrane Biology
Volume173
Issue number1
DOIs
StatePublished - Jan 1 2000
Externally publishedYes

Fingerprint

Proton-Translocating ATPases
Epithelium
Sodium
Rabbits
Potassium
Ouabain
Sodium-Hydrogen Antiporter
bafilomycin A1
Fluorescence Microscopy
Inhibitory Concentration 50
Spectrum Analysis
Epithelial Cells
5-dimethylamiloride

Keywords

  • Bafilomycin A
  • Cytoplasmic pH
  • Cytoplasmic sodium
  • Dimethylamiloride
  • H-ATPase

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

Cite this

Studies on H+-ATPase in cultured rabbit nonpigmented ciliary epithelium. / Hou, Y.; Delamere, Nicholas A.

In: The Journal of Membrane Biology, Vol. 173, No. 1, 01.01.2000, p. 67-72.

Research output: Contribution to journalArticle

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