HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Al-Nakkash, L. Articles by Reinach, P. S. Search for Related Content PubMed PubMed Citation Articles by Al-Nakkash, L. Articles by Reinach, P. S.

Activation of a CFTR-Mediated Chloride Current in a Rabbit Corneal Epithelial Cell Line

¹ From the Department of Physiology, School of Medicine, University of Missouri-Columbia; and ² Department Biological Sciences, SUNY College of Optometry, New York, New York.

PURPOSE. To determine whether there is gene expression and functional activity of cystic fibrosis transmembrane conductance regulator protein (CFTR) in an SV40-immortalized rabbit corneal epithelial cell line, tRCE.

METHODS. Both whole-cell and cell-attached patch-clamp techniques were used to examine the biophysical characteristics of the cAMP-dependent chloride current. The molecular identity of this conductance was evaluated using RT-PCR analysis.

RESULTS. In whole-cell patch-clamp studies, a cAMP-dependent chloride conductance was further facilitated by the known CFTR activator genistein (20 µM). Kinetic analysis of cell-attached patches containing few channels ascertained that genistein increased the chloride channel activity by increasing channel open probability (via an increased channel open time and a decreased channel closed time). In addition, in the presence of a reduced forskolin concentration (i.e., 100 nM), the chloride conductance generated could be augmented by the nonspecific phosphodiesterase enzyme inhibitor, IBMX (100 µM), implicating the importance of intracellular cAMP in the regulation of this conductance. Furthermore, this conductance exhibited voltage-dependent inhibition in the presence of the CFTR chloride channel blocker glibenclamide (250 µM), but was DIDS insensitive (500 µM). Consistent with the presence of a CFTR-mediated chloride conductance, the expression of CFTR-mRNA was detected using RT-PCR. Sequence analysis of the product revealed 99.4% homology to that described for rabbit CFTR.

CONCLUSIONS. In tRCE cells, there is gene expression and functional CFTR activity. Its presence may have important therapeutic implications in corneal epithelial diseases resulting from declines in transepithelial secretory and fluid transport activity.

This article has been cited by other articles:

				M. H. Levin and A. S. Verkman CFTR-Regulated Chloride Transport at the Ocular Surface in Living Mice Measured by Potential Differences Invest. Ophthalmol. Vis. Sci., April 1, 2005; 46(4): 1428 - 1434. [Abstract] [Full Text] [PDF]

				P. G. Milhaud, S. R. Pondugula, J. H. Lee, M. Herzog, J. Lehouelleur, P. Wangemann, A. Sans, and D. C. Marcus Chloride secretion by semicircular canal duct epithelium is stimulated via beta 2-adrenergic receptors Am J Physiol Cell Physiol, December 1, 2002; 283(6): C1752 - C1760. [Abstract] [Full Text] [PDF]