title: CFTR regulation of intracellular calcium in normal and cystic fibrosis human airway epithelia.
abstract: In cystic fibrosis airway epithelia, mutation of the CFTR protein causes a reduced response of Cl(-) secretion to secretagogues acting via cAMP. Using a Ca(2+) imaging system, the hypothesis that CFTR activation may permit ATP release and regulate [Ca(2+)](i) via a receptor-mediated mechanism, is tested in this study. Application of external nucleotides produced a significant increase in [Ca(2+)](i) in normal (16HBE14o(-) cell line and primary lung culture) and in cystic fibrosis (CFTE29o(-) cell line) human airway epithelia. The potency order of nucleotides on [Ca(2+)](i) variation was UTP >> ATP > UDP > ADP > AMP > adenosine in both cell types. The nucleotide [Ca(2+)](i) response could be mimicked by activation of CFTR with forskolin (20 microm) in a temperature-dependent manner. In 16HBE14o(-) cells, the forskolin-induced [Ca(2+)](i) response increased with increasing temperature. In CFTE29o(-) cells, forskolin had no effect on [Ca(2+)](i) at body temperature-forskolin-induced [Ca(2+)](i) response in CF cells could only be observed at low experimental temperature (14 degrees C) or when cells were cultured at 26 degrees C instead of 37 degrees C. Pretreatment with CFTR channel blockers glibenclamide (100 microm) and DPC (100 microm), with hexokinase (0.5 U/mg), and with the purinoceptor antagonist suramin (100 microm), inhibited the forskolin [Ca(2+)](i) response. Together, these results demonstrate that once activated, CFTR regulates [Ca(2+)](i) by mediating nucleotide release and activating cell surface purinoceptors in normal and CF human airway epithelia.
authors.affiliation: Wellcome Trust Cellular Physiology Research Unit, Department of Physiology, University College Cork, Ireland.
authors.forename: D E
authors.initials: DE
authors.lastname: Walsh
authors.forename: B J
authors.initials: BJ
authors.lastname: Harvey
authors.forename: V
authors.initials: V
authors.lastname: Urbach
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003550:Cystic Fibrosis / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005905:Glyburide / Q000494:pharmacology; D006593:Hexokinase / Q000494:pharmacology; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D009711:Nucleotides / Q000494:pharmacology; D011983:Receptors, Purinergic / Q000187:drug effects / Q000378:metabolism; D013498:Suramin / Q000494:pharmacology; D013696:Temperature; D062367:ortho-Aminobenzoates / Q000494:pharmacology
chemical_list: C505032:CFTR protein, human; D009711:Nucleotides; D011983:Receptors, Purinergic; D062367:ortho-Aminobenzoates; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; D013498:Suramin; D000255:Adenosine Triphosphate; C001209:fenamic acid; D006593:Hexokinase; D005905:Glyburide; D002118:Calcium