PMID: 11923259Mar 30, 2002Paper

Enhancement of HCO(3)(-) permeability across the apical membrane of bovine corneal endothelium by multiple signaling pathways

Investigative Ophthalmology & Visual Science
Yan ZhangJ A Bonanno

Abstract

In this study, the involvement of signaling pathways in the regulation of HCO(3)(-) permeability across the apical membrane of the corneal endothelium was examined. Cultured bovine corneal endothelial cells (CBCECs) were grown to confluence on permeable membranes. Apical and basolateral sides were perfused with a HCO(3)(-)-rich Cl(-)-free Ringer's solution (28.5 mM; pH 7.5). Relative changes in apical HCO(3)(-) permeability were assayed by pulsing the apical perfusion bath with a low-HCO(3)(-) Cl(-)-free Ringer's solution (2.85 mM; pH 6.5), in the presence or absence of agonists or inhibitors, and comparing the rates of change in intracellular pH (pH(i)), as measured with a pH-sensitive dye. Ca(2+)-activated signaling was measured with the Ca(2+)-sensitive dye Fura-2. Qualitative changes in membrane potential (E(m)) were measured with a voltage-sensitive dye. RT-PCR using calcium-activated chloride channel (CLCA)-specific primers was used to examine the expression of CLCA in the corneal endothelium. The adenoceptor agonist adenosine (20 M) enhanced HCO(3)(-) permeability by a factor of 2. Forskolin (40 microM) exerted a 6.3-fold increase of HCO(3)(-) permeability, which was inhibited by the Cl(-) channel blockers, glibenclamide...Continue Reading

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