[Ion transport in nasal and paranasal sinus mucosa in mucoviscidosis and chronic sinusitis].
Cystic fibrosis (CF) is the most commonly inherited disease in Caucasians and is caused by a mutation in the gene encoding a membrane transport protein. This cystic fibrosis transmembrane conductance regulator (CFTR) is thought to be an apical Cl- channel activated by intracellular cAMP. Most recent findings suggest that CFTR is more than a pure Cl- channel and might be involved in the regulation of other transport systems. In the present study we show that CFTR as a Cl- channel plays only a minor role in primary cultured human nasal epithelium derived from non-CF and CF patients. These findings are especially of interest for non-CF human nasal epithelia in which CFTR is correctly inserted. In both tissues Cl- secretion is negligible as compared with Na+ absorption. We confirm and expand our previous observations that Na+ absorption in human nasal epithelium is the dominant ion transport process and that Cl- secretion is detectable in both CF and non-CF tissue. Moreover, we show that cAMP and ATP were not able to stimulate any silent Cl- channels in CF or non-CF human nasal epithelial cells. We further give evidence that in human nasal CF and non-CF epithelium Na+ absorption is mediated by epithelial Na+ channels (ENaC) that are either different from those of other epithelia or which exhibit altered regulation. These differences between Na+ channels of human nasal epithelium and "classical" epithelial Na+ channels include lack of activation by the intracellular second messenger cAMP and the steroid hormone aldosterone. We show further that human nasal Na+ channels are inhibited by Cl- channel blockers and exhibit a different pharmacology towards common Na+ channel blockers.
Rückes-Nilges
C
C
Institut für Tierphysiologie, Justus-Liebig-Universität Giessen.
Weber
U
U
Popp
C
C
Fryen
A
A
Klimek
T
T
Glanz
H
H
Lindemann
H
H
Münker
G
G
Clauss
W
W
Weber
W M
WM
D018118:Chloride Channels / Q000235:genetics / Q000502:physiology*; D002908:Chronic Disease; D046508:Culture Techniques; D000242:Cyclic AMP / Q000502:physiology; D003550:Cystic Fibrosis / Q000235:genetics / Q000503:physiopathology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000502:physiology; D006801:Humans; D009297:Nasal Mucosa / Q000503:physiopathology*; D009298:Nasal Polyps / Q000235:genetics / Q000503:physiopathology; D009669:Nose Neoplasms / Q000235:genetics / Q000503:physiopathology; D010256:Paranasal Sinuses / Q000503:physiopathology*; D012016:Reference Values; D012852:Sinusitis / Q000235:genetics / Q000503:physiopathology*; D015222:Sodium Channels / Q000235:genetics / Q000502:physiology*
C505032:CFTR protein, human; D018118:Chloride Channels; D015222:Sodium Channels; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000242:Cyclic AMP