Relationship between membrane potential and external potassium in human glioblastoma cells in tissue culture

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Abstract
Cells from a human glioblastoma (TC 526) maintained in tissue culture for ten years had a mean membrane potential of 27 ± 0.9 mV at an external potassium concentration [K0] of 5.3 mM. When [K0] was varied between 2.5 and 5.3 mM, membrane potential changes were close to those predicted by the Nernst equation. At higher [K0], the Nernstian slope was approached only in the presence of 10−5 M ouabain, which did not affect membrane potential at a [K0] of 5.3 mM. An electrogenic sodium pump activated by high [K0] could explain these findings; such a mechanism has been demonstrated in other tissues.