Cx46 hemichannels contribute to the sodium leak conductance in lens fiber cells

The lens is proposed to have an internal microcirculation system consisting of continuously circulating ionic fluxes that play an essential role in maintaining lens transparency. One of the key components of this system is the sodium leak conductance. Here we investigate the contribution of Cx46 hem...

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Bibliographic Details
Published in:American Journal of Physiology: Cell Physiology Vol. 306; no. 5; p. C506
Main Authors: Ebihara, Lisa, Korzyukov, Yegor, Kothari, Sorabh, Tong, Jun-Jie
Format: Journal Article
Language:English
Published: United States 01.03.2014
Subjects:
Animals
Cell Membrane - metabolism
Cell Membrane Permeability
Connexins - deficiency
Connexins - genetics
Connexins - metabolism
Eye Proteins - genetics
Ion Channel Gating
Ion Transport
Lens, Crystalline - cytology
Lens, Crystalline - metabolism
Membrane Potentials
Mice
Mice, Knockout
Sodium - metabolism
lens
hemichannel
connexin
Cx46
ISSN:1522-1563, 1522-1563
Online Access:Get more information
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Summary:The lens is proposed to have an internal microcirculation system consisting of continuously circulating ionic fluxes that play an essential role in maintaining lens transparency. One of the key components of this system is the sodium leak conductance. Here we investigate the contribution of Cx46 hemichannels to the basal membrane permeability of peripheral fiber cells isolated from transgenic mouse lenses lacking Cx50 or both Cx50 and Cx46 (dKO) using the whole cell patch-clamp technique. Our results show that Cx46 hemichannels were largely closed at a resting voltage of -60 mV in the presence of millimolar divalent cation concentrations. However, even though the vast majority of these channels were closed at -60 mV, a small, persistent, inward current could still be detected. This current could be mostly blocked by exposure to 1 mM La(3+) and was not observed in fiber cells isolated from dKO mouse lenses suggesting that it was due to Cx46 hemichannels. In addition, Cx50(-/-) fiber cells showed increased open channel noise and a depolarized resting potential compared with dKO fiber cells. Exposure of Cx50(-/-) fiber cells to La(3+) hyperpolarized the resting potential to -58 mV, which is similar to the value of resting potential measured in dKO fiber and significantly reduced the open channel noise. In conclusion, these results suggest that Cx46 hemichannels may contribute to the sodium leak conductance in lens fiber cells.
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ISSN:1522-1563
1522-1563
DOI:10.1152/ajpcell.00353.2013