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Masayuki Takahira, Norimasa Sakurada, Yasunori Segawa, Yutaka Shirao; Two Types of K+ Currents Modulated by Arachidonic Acid in Bovine Corneal Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2001;42(8):1847-1854.
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purpose. Fenamate sensitivity of the large-conductance K+ current in
the corneal epithelium suggests that K+ transport could be
modulated by arachidonic acid (AA) and/or its metabolites, which also
regulate corneal epithelial migration. The main purpose of this study
was to investigate AA-induced modulation of K+ currents
expressed in the bovine corneal epithelium.
methods. Freshly isolated bovine corneal epithelial cells were perfused with
Ringer solution. Whole-cell currents were recorded by using either the
conventional whole-cell–patch or the perforated-patch configuration.
results. Two distinct types of K+ currents dominated the whole-cell
current. The first was a voltage-gated K+ current that was
inactivated completely by membrane depolarization. The inactivating
voltage-gated K+ current was largest in presumptive basal
cells. The second was a noisy, sustained K+ current that
was never inactivated and seemed to be a counterpart of the
large-conductance K+ current reported in the rabbit corneal
epithelium. External application of AA (5–20 μM) inhibited the
inactivating voltage-gated K+ current and augmented the
noisy, sustained K+ current. Identical dual modulation was
induced by other fatty acids (e.g., palmitoleic acid) that are not
substrates for enzymes in the AA cascade.
conclusions. An inactivating voltage-gated K+ channel was identified for
the first time in the corneal epithelium. AA and some fatty acids may
directly activate the large-conductance K+ channel to
augment its housekeeping functions in corneal epithelial
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