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Lisa Ebihara, Yegor Korzyukov; Characterization Of Membrane Properties Of Lens Fiber Cells Isolated From Double Knockout (Cx46(-/-);Cx50(-/-)) Mouse Lenses. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1048.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the membrane properties of differentiating fiber cells isolated from double knockout (Cx46(-/-); Cx50(-/-)) mouse lenses.
Differentiating fiber cells were isolated from mouse lenses using collagenase.. Membrane currents were recorded using whole cell patch clamping.
We studied fiber cells from double knockout lenses ranging between 50 and 500 microns in length. All of the fiber cells were dominated by K(+) conductances with little contribution from Cl(-) or other cation conductances when measured in isotonic NaCl Ringers containing 1 mM Ca(2+) and 1 mM Mg(2+). Two K(+) conductances were identified: (1) an outwardly rectifying K(+) conductance that could be blocked by replacing internal K(+) by Cs(+); (2) a barium-sensitive inward rectifier. There was no correlation between the size of the fiber cell, its resting potential or the magnitude of the whole cell K(+) currents. To study the effects of hypotonic stress, fiber cells isolated from double knockout lenses were exposed to solution rendered hypoosmotic by omission of mannitol. Exposure of the fiber cell to hypoosmotic challenge produced a detectible swelling. This swelling was accompanied by an increase in an outwardly activating component of the whole-cell current at large depolarizing potentials. The whole cell current recovered to its control state following reperfusion with isotonic NaCl Ringers. The properties of this current were similar to those of the volume activated chloride current found in other tissues.
Our results demonstrate that membrane conductance of peripheral fiber cells isolated from double knockout lenses are dominated by K(+) conductances which permit the fiber cells to maintain a negative resting potential and normal transmembrane ionic gradients even in the absence of gap junctional coupling. They also contain volume activated chloride channels.
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