Contribution of a H+ pump in determining the resting potential of neuroblastoma cells.

Abstract

The aim of this work was to examine the effects of changes in external K+ concentration (Ko) around its physiological value, of various K+ channels blockers, including internal Cs+, of vacuolar H(+)-ATPase inhibitors and of the protonophore CCCP on the resting potential and the voltage-dependent K+ current of differentiated neuroblastoma x glioma hybrid NG108-15 cells using the whole-cell patch-clamp technique. The results are as follows: (i) under standard conditions (Ko = 5 mM) the membrane potential was -60 +/- 1 mV. It was unchanged when Ko was decreased to 1 mM and was depolarized by 4 +/- 1 mV when Ko was increased to 10 mM. (ii) Internal Cs+ depolarized the membrane by 21 +/- 3 mV. (iii) The internal application of the vacuolar H(+)-ATPase inhibitors N-ethylmaleimide (NEM), NO3- and bafilomycin A1 (BFA) depolarized the membrane by 15 +/- 2, 18 +/- 2 and 16 +/- 2 mV, respectively. (iv) When NEM or BFA were added to the internal medium containing Cs+, the membrane was depolarized by 45 +/- 1 and 42 +/- 2 mV, respectively. (v) The external application of CCCP induced a transient depolarization followed by a prolonged hyperpolarization. This hyperpolarization was absent in BFA-treated cells. The voltage-dependent K+ current was increased at negative voltages and decreased at positive voltages by NEM, BFA and CCCP. Taken together, these results suggest that under physiological conditions, the resting potential of NG108-15 neuroblastoma cells is maintained at negative values by both voltage-dependent K+ channels and an electrogenic vacuolar type H(+)-ATPase.

• Authors: V Gérard, B Rouzaire-Dubois, J M Dubois
• Journal: The Journal of membrane biology (J Membr Biol) Vol. 137 Issue 2 Pg. 119-25 (Jan 1994) ISSN: 0022-2631 [Print] United States
• PMID: 8006950 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Antifungal Agents
• Macrolides
• Nitrites
• Potassium Channels
• Proton Pumps
• Cesium
• Carbonyl Cyanide m-Chlorophenyl Hydrazone
• Ouabain
• bafilomycin A1
• Ethylmaleimide
• Potassium

Topics

• Animals
• Anti-Bacterial Agents (pharmacology)
• Antifungal Agents (pharmacology)
• Carbonyl Cyanide m-Chlorophenyl Hydrazone (pharmacology)
• Cell Membrane (physiology, ultrastructure)
• Cesium (pharmacology)
• Ethylmaleimide (pharmacology)
• Glioma (pathology, physiopathology, ultrastructure)
• Macrolides
• Membrane Potentials (physiology)
• Mice
• Neuroblastoma (pathology, physiopathology, ultrastructure)
• Nitrites (pharmacology)
• Ouabain (pharmacology)
• Potassium (pharmacology)
• Potassium Channels (physiology)
• Proton Pumps (physiology)
• Rats
• Time Factors
• Tumor Cells, Cultured