ISSN:
1432-1424
Keywords:
Neuroblastoma cells
;
K+ channels
;
Vacuolar H+-ATPase
;
Resting potential
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The aim of this work was to examine the effects of changes in external K+ concentration (K o ) 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 (K o =5 mm) the membrane potential was −60±1 mV. It was unchanged when K o 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), NO 3 − 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00233481
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