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Determination of the membrane potential of cultured mammalian schwann cells and its sensitivity to potassium using a thiocarbocyanine fluorescent dye
Author(s) -
Hargittai P. T.,
Youmans S. J.,
Lieberman E. M.
Publication year - 1991
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.440040608
Subject(s) - valinomycin , membrane potential , ionophore , biophysics , gramicidin , membrane , fluorescence , microelectrode , potassium , biology , voltage sensitive dye , chemistry , biochemistry , optics , electrode , physics , organic chemistry
Abstract The membrane potential of cultured rat sciatic nerve Schwann cells was determined with conventional microelectrode and voltage‐sensitive fluorescent dye, Di‐S‐C 3 (5), optical techniques. The value for membrane potential obtained with microelectrodes was −42.1 ± 4.7 mV (n = 8). Using optically determined fluorescent intensity changes caused by changes in external potassium ion concentration, in the presence or absence of valinomycin (null point method), the membrane potential was estimated at −45.7 ± 6.2 mV (n = 7); with a gramicidin and valinomycin double ionophore method it was −52.2 ± 9.1 (n = 4). The membrane potential of Schwann cells was found to be potassium sensitive at and above the physiological range of [K + ] at 27.5 mV/10 × Δ[K + ], which is approximately half the Nernstian value. This result suggests that other ion permeabilities strongly influence the resting membrane potential of cultured Schwann cells. Since Na + had little effect on the membrane potential, it is concluded that Cl − is a likely candidate for the other permeant ionic species. The optical method has been shown to be a useful tool for the systematic study of the membrane potential of Schwann cells in culture and for the characterization of its ionic basis and regulation.