CFTR Expression in C127 Cells Is Associated with Enhanced Cell Shrinkage and ATP Extrusion in Cl−-Free Medium

Abstract

In this study we have employed three lines of C127 murine cells, C127 CFTRw/t, C127 CFTRΔF508 and C127 mock, transfected with, respectively, wild type, ΔF508 mutant human CFTR cDNA or the vector only. In the first 10 minutes of a Cl−-free incubation the three cell lines exhibit a significant shrinkage due to a loss of K+and Cl−. However, C127 CFTRw/t cells shrink more than C127 CFTRΔF508 and the mock cells. The supplementation of Cl−-free medium with ATP causes a marked decrease in the cell volume of C127 CFTRΔF508 and of the mock cells but not of C127 CFTRw/t cells. ATP effect is mimicked by adenosine 5′-O-(3-thiotriphosphate), but neither by adenosine nor by UTP. Measurements of extracellular ATP indicate that during the Cl−-free incubation C127 CFTRw/t cells extrude more ATP than the other two cell lines. The results are consistent with the hypothesis that CFTR enhances K+and Cl−permeabilities by promoting the extrusion of ATP.