Electrical membrane properties of a cell clone derived from human nonpigmented ciliary epithelium.
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.
Helbig
H
H
Institut für Klinische Physiologie, Klinikum Steglitz, Freien Universität Berlin, Federal Republic of Germany.
Korbmacher
C
C
Wohlfarth
J
J
Coca-Prados
M
M
Wiederholt
M
M
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002924:Ciliary Body / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D002999:Clone Cells; D003494:Cyclamates / Q000494:pharmacology; D004553:Electric Conductivity; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010042:Ouabain / Q000494:pharmacology; D010858:Pigmentation; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology
D002712:Chlorides; D003494:Cyclamates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010042:Ouabain; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium; D002118:Calcium