Activation of Cl- currents by intracellular chloride in fibroblasts stably expressing the human cystic fibrosis transmembrane conductance regulator.
The Cl- conductance of a mouse fibroblast cell line (LTK- cells) that was stably transfected with the human CFTR (cystic fibrosis transmembrane conductance regulator) complementary DNA was studied. Single Cl- channel activity was observed only after treatment of the cells with forskolin, the single-channel conductance being 6.2 +/- 0.2 pS with a linear current-voltage relationship. In CFTR+ cells, the whole-cell current at +90 mV increased from 7.3 +/- 2.7 pA/pF (n = 12) to 46.1 +/- 11.2 pA/pF (n = 5) after addition of dibutyryl-cyclic AMP (10(-4) M) to the bath. Increasing the intracellular Cl- concentration to 150 mM activated linear Cl- currents in the absence of cyclic AMP in CFTR+ (n = 42) but not in CFTR- cells (n = 4). Similar Cl- current was also activated by high intracellular I- concentration. These results indicate that the CFTR-induced Cl- conductance in LTK- cells can be activated by either cyclic AMP or high intracellular halide concentrations.
Wang
X
X
Respiratory Research Division, Hospital for Sick Children, University of Toronto, ON, Canada.
Marunaka
Y
Y
Fedorko
L
L
Dho
S
S
Foskett
J K
JK
O'Brodovich
H
H
D000818:Animals; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism; D003550:Cystic Fibrosis / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009431:Neural Conduction / Q000502:physiology
C505032:CFTR protein, human; D018118:Chloride Channels; D002712:Chlorides; D008565:Membrane Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D000242:Cyclic AMP