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Electrical properties of mammalian lens epithelial gap junction channels
P J Donaldson1, M Roos, C Evans
1Department of Biochemistry and Molecular Biology, School of Biological Sciences, University of Auckland, New Zealand.
Purpose:
To establish an "electrical fingerprint" for the gap junction channels between mammalian lens epithelial cells.
Methods:
The double whole cell patch clamp technique was applied to isolated cell pairs obtained from mouse lens epithelium and a continuous cell line of lens epithelial cells derived from the sheep lens (SLE 2.1).
Results:
The junctional conductance in mouse lens epithelial cells and in cultured SLE 2.1 cells was found to be moderately voltage dependent. SLE 2.1 cells were analyzed in more detail. The voltage dependence could be described by a Boltzmann distribution with Vo = +/- 63.1 mV and Gmin = 0.34. In cell pairs that exhibited spontaneously low junctional conductance, single channel events could be distinguished. Single gap junction channel currents had a linear current-voltage relationship. A frequency histogram of single channel conductances from eight cell pairs had three major peaks of 35, 60 and 97 pS.
Conclusion:
The electrical properties of gap junction channels between mammalian lens epithelial cells were virtually identical to those previously reported for transfected cell lines expressing connexin43. The authors' physiological data are therefore in agreement with molecular studies that have identified connexin43 as the major connexin of lens epithelial cells.