Cystic fibrosis affects chloride and sodium channels in human airway epithelia

1989 ◽  
Vol 67 (10) ◽  
pp. 1362-1365 ◽  
Author(s):  
Marek Duszyk ◽  
Andrew S. French ◽  
S. F. Paul Man
Keyword(s):  
Cystic Fibrosis ◽  
Sodium Channels ◽  
Chloride Channels ◽  
Genetic Defect ◽  
Airway Epithelial Cells ◽  
Cell Membrane Permeability ◽  
Single Type ◽  
Airway Epithelial ◽  
Patch Clamp Technique ◽  
The One

Abnormalities of epithelial function in cystic fibrosis (CF) have been linked to defects in cell membrane permeability to chloride or sodium ions. Recently, a class of chloride channels in airway epithelial cells have been reported to lack their usual sensitivity to phosphorylation via cAMP-dependent protein kinase, suggesting that CF could be due to a single genetic defect in these channels. We have examined single chloride and sodium channels in control and CF human nasal epithelia using the patch-clamp technique. The most common chloride channel was not the one previously associated with CF, but it was also abnormal in CF cells. In addition, the number of sodium channels was unusually high in CF. These findings suggest a wider disturbance of ion channel properties in CF than would be produced by a defect in a single type of channel.Key words: ion channels, cystic fibrosis, airway, epithelium.

Basal chloride currents in murine airway epithelial cells: modulation by CFTR

1998 ◽  
Vol 274 (4) ◽  
pp. C904-C913 ◽  
Author(s):  
R. Tarran ◽  
M. A. Gray ◽  
M. J. Evans ◽  
W. H. Colledge ◽  
R. Ratcliff ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Airway Epithelial Cells ◽  
Transmembrane Conductance Regulator ◽  
Airway Epithelial ◽  
Wild Type ◽  
Patch Clamp Technique ◽  
Chloride Currents ◽  
Cation Permeability ◽  
Current Voltage ◽  
Respiratory Cells

We have isolated ciliated respiratory cells from the nasal epithelium of wild-type and cystic fibrosis (CF) null mice and used the patch-clamp technique to investigate their basal conductances. Current-clamp experiments on unstimulated cells indicated the presence of K+ and Cl− conductances and, under certain conditions, a small Na+conductance. Voltage-clamp experiments revealed three distinct Cl− conductances. I tv-indep was time and voltage independent with a linear current-voltage ( I- V) plot; I v-actexhibited activation at potentials greater than ±50 mV, giving an S-shaped I- Vplot; and I hyp-act was activated by hyperpolarizing potentials and had an inwardly rectified I- Vplot. The current density sequence was I hyp-act = I v-act ≫ I tv-indep. These conductances had Cl−-to- N-methyl-d-glucamine cation permeability ratios of between 2.8 and 10.3 and were unaffected by tamoxifen, flufenamate, glibenclamide, DIDS, and 5-nitro-2-(3-phenylpropylamino) benzoic acid but were inhibited by Zn2+ and Gd3+. I tv-indep and I v-act were present in wild-type and CF cells at equal density and frequency. However, I hyp-actwas detected in only 3% of CF cells compared with 26% of wild-type cells, suggesting that this conductance may be modulated by cystic fibrosis transmembrane conductance regulator (CFTR).

scholarly journals Lubiprostone activates non-CFTR-dependent respiratory epithelial chloride secretion in cystic fibrosis mice

2008 ◽  
Vol 295 (5) ◽  
pp. L933-L940 ◽  
Author(s):  
Kelvin D. MacDonald ◽  
Karen R. McKenzie ◽  
Mark J. Henderson ◽  
Charles E. Hawkins ◽  
Neeraj Vij ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Chloride Channels ◽  
Chloride Secretion ◽  
Airway Epithelial Cells ◽  
Sodium Reabsorption ◽  
Airway Epithelial ◽  
Wild Type ◽  
Voltage Dependent ◽  
Clear Dose Response ◽  
Apical Membranes

Periciliary fluid balance is maintained by the coordination of sodium and chloride channels in the apical membranes of the airways. In the absence of the cystic fibrosis transmembrane regulator (CFTR), chloride secretion is diminished and sodium reabsorption exaggerated. ClC-2, a pH- and voltage-dependent chloride channel, is present on the apical membranes of airway epithelial cells. We hypothesized that ClC-2 agonists would provide a parallel pathway for chloride secretion. Using nasal potential difference (NPD) measurements, we quantified lubiprostone-mediated Cl− transport in sedated cystic fibrosis null (gut-corrected), C57Bl/6, and A/J mice during nasal perfusion of lubiprostone (a putative ClC-2 agonist). Baseline, amiloride-inhibited, chloride-free gluconate-substituted Ringer with amiloride and low-chloride Ringer plus lubiprostone (at increasing concentrations of lubiprostone) were perfused, and the NPD was continuously recorded. A clear dose-response relationship was detected in all murine strains. The magnitude of the NPD response to 20 μM lubiprostone was −5.8 ± 2.1 mV (CF, n = 12), −8.1 ± 2.6 mV (C57Bl/6 wild-type, n = 12), and −5.3 ± 1.2 mV (AJ wild-type, n = 8). A cohort of ClC-2 knockout mice did not respond to 20 μM lubiprostone ( n = 6, P = 0.27). In C57Bl/6 mice, inhibition of CFTR with topical application of CFTR inhibitor-172 did not abolish the lubiprostone response, thus confirming the response seen is independent of CFTR regulation. RT-PCR confirmed expression of ClC-2 mRNA in murine lung homogenate. The direct application of lubiprostone in the CF murine nasal airway restores nearly normal levels of chloride secretion in nasal epithelia.

scholarly journals Expression of the chloride channel CLC-K in human airway epithelial cells

2005 ◽  
Vol 83 (12) ◽  
pp. 1123-1128 ◽  
Author(s):  
Jennifer L. Mummery ◽  
Jennifer Killey ◽  
Paul Linsdell
Keyword(s):  
Cystic Fibrosis ◽  
Chloride Channel ◽  
Chloride Channels ◽  
Human Cell Line ◽  
Genetic Mutation ◽  
Airway Epithelial Cells ◽  
K Channel ◽  
Airway Epithelial ◽  
Submucosal Gland ◽  
Patch Clamp Recording

Airway submucosal gland function is severely disrupted in cystic fibrosis (CF), as a result of genetic mutation of the cystic fibrosis transmembrane conductance regulator (CFTR), an apical membrane Cl– channel. To identify other Cl– channel types that could potentially substitute for lost CFTR function in these cells, we investigated the functional and molecular expression of Cl– channels in Calu-3 cells, a human cell line model of the submucosal gland serous cell. Whole cell patch clamp recording from these cells identified outwardly rectified, pH- and calcium-sensitive Cl– currents that resemble those previously ascribed to ClC-K type chloride channels. Using reverse transcription – polymerase chain reaction, we identified expression of mRNA for ClC-2, ClC-3, ClC-4, ClC-5, ClC-6, ClC-7, ClC-Ka, and ClC-Kb, as well as the common ClC-K channel β subunit barttin. Western blotting confirmed that Calu-3 cells express both ClC-K and barttin protein. Thus, Calu-3 cells express multiple members of the ClC family of Cl– channels that, if also expressed in native submucosal gland serous cells within the CF lung, could perhaps act to partially substitute lost CFTR function. Furthermore, this work represents the first evidence for functional ClC-K chloride channel expression within the lung.

Differential expression of ORCC and CFTR induced by low temperature in CF airway epithelial cells

1995 ◽  
Vol 268 (1) ◽  
pp. C243-C251 ◽  
Author(s):  
M. E. Egan ◽  
E. M. Schwiebert ◽  
W. B. Guggino
Keyword(s):  
Cystic Fibrosis ◽  
Epithelial Cells ◽  
Incubation Temperature ◽  
Cell Types ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Channel Activity ◽  
Patch Clamp Recording ◽  
Cl Channel ◽  
Channel Expression

When nonepithelial cell types expressing the delta F508-cystic fibrosis transmembrane conductance regulator (CFTR) mutation are grown at reduced temperatures, the mutant protein can be properly processed. The effect of low temperatures on Cl- channel activity in airway epithelial cells that endogenously express the delta F508-CFTR mutation has not been investigated. Therefore, we examined the effect of incubation temperature on both CFTR and outwardly rectifying Cl- channel (ORCC) activity in normal, in cystic fibrosis (CF)-affected, and in wild-type CFTR-complemented CF airway epithelia with use of a combination of inside-out and whole cell patch-clamp recording, 36Cl- efflux assays, and immunocytochemistry. We report that incubation of CF-affected airway epithelial cells at 25-27 degrees C is associated with the appearance of a protein kinase A-stimulated CFTR-like Cl- conductance. In addition to the appearance of CFTR Cl- channel activity, there is, however, a decrease in the number of active ORCC when cells are grown at 25-27 degrees C, suggesting that the decrease in incubation temperature may be associated with multiple alterations in ion channel expression and/or regulation in airway epithelial cells.

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