Determination of the membrane potential of cultured mammalian schwann cells and its sensitivity to potassium using a thiocarbocyanine fluorescent dye
✍ Scribed by P. T. Hargittai; S. J. Youmans; E. M. Lieberman
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 602 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0894-1491
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✦ Synopsis
The membrane potential of cultured rat sciatic nerve Schwann cells was determined with conventional microelectrode and voltage-sensitive fluorescent dye, Di-S-C,(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/lOx A[K'l, 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 C1F 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.