Properties of whole-cell ionic currents in cultured human corneal epithelial cells.
OBJECTIVE
To identify and partially characterize the ionic currents contributing to the whole-cell conductance of cultured human corneal epithelial cells.


METHODS
Epithelial cells were scraped from human donor corneas and cultured for use in patch-clamp experiments. Amphotericin B and the perforated-patch configuration were used to measure whole-cell currents in cells isolated from confluent monolayers.


RESULTS
Cell monolayers exhibited cobblestone morphology and were immunopositive for corneal epithelium-specific cytokeratin. Single cells had a capacitance of 21 +/- 2 pF and expressed similar types of ionic currents regardless of passage number. In descending order of frequency of occurrence, cells exhibited a nonselective cation current active at depolarized voltages and insensitive to Ba2+ and Gd3+; an outwardly rectifying K+ current active at depolarized voltages, stimulated by flufenamic acid and inhibited by tetraethylammonium; a voltage-gated inward Na+ current; an outwardly rectifying K+ current active at hyperpolarized voltages, stimulated by flufenamic acid, blocked by Ba2+, and insensitive to diltiazem; an inwardly rectifying K+ current; and a nonselective cation current inhibited by flufenamic acid.


CONCLUSIONS
Our results are consistent with those in previous studies of noncultured epithelia from rabbit and human corneas showing an outwardly rectifying K+ current active at hyperpolarized voltages and a nonselective cation current active at depolarized voltages and insensitive to Ba2+. These data suggest cultured cells may be useful in determining the physiological role of ion channels in corneal epithelia and may aid in the development of a cell-based model for the examination of the effects of wounding and toxic agents on the human cornea.
Bockman
C S
CS
Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska, USA.
Griffith
M
M
Watsky
M A
MA
D000666:Amphotericin B / Q000494:pharmacology; D002478:Cells, Cultured; D019573:Epithelium, Corneal / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005439:Flufenamic Acid / Q000494:pharmacology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007473:Ion Channels / Q000502:physiology*; D017136:Ion Transport; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000502:physiology; D012964:Sodium / Q000378:metabolism
D007473:Ion Channels; D015221:Potassium Channels; D005439:Flufenamic Acid; D000666:Amphotericin B; D012964:Sodium; D011188:Potassium