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H Helbig, C Korbmacher, J Wohlfarth, M Coca-Prados, M Wiederholt; Electrical membrane properties of a cell clone derived from human nonpigmented ciliary epithelium.. Invest. Ophthalmol. Vis. Sci. 1989;30(5):882-889.
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© ARVO (1962-2015); The Authors (2016-present)
Intracellular potentials were measured in a SV-40 virus-transformed cell clone derived from human nonpigmented ciliary epithelium using the microelectrode technique. (1) Membrane potential averaged -50.2 mV (+/- 0.6, n = 207). (2) Increasing the extracellular K+ concentration depolarized the membrane voltage. The amplitude of this potential response was reduced in the presence of 1 mM Ba2+. (3) Superfusing the cells with a Ca2+-free solution containing 1 mM EGTA depolarized the intracellular potential and diminished the voltage response upon increasing extracellular K+. (4) Extracellular alkalinization hyperpolarized the membrane potential and increased the voltage amplitude on increasing extracellular K+. (5) Addition of ouabain immediately reduced the intracellular potential. Removing extracellular K+ depolarized membrane voltage, readdition of K+ after K+ depletion transiently hyperpolarized intracellular voltage. Both potential responses were inhibited in the presence of ouabain. (6) Replacing extracellular Cl- by cyclamate resulted in a transient depolarization followed by a hyperpolarization. In the presence of SITS or DIDS (greater than or equal to 0.1 mM) the electrical responses of the cell membrane to Cl- replacement were blocked. We conclude that cultured human nonpigmented ciliary epithelial cells possess an electrogenic Na+/K+-ATPase, a K+ conductance modulated by Ca2+ and pH, and a Cl- conductance sensitive to stilbene derivatives.
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