Regulation of Ca(2+)-activated chloride channels by cAMP and CFTR in parotid acinar cells.
The effect of intracellular cAMP and cystic fibrosis conductance regulator (CFTR) protein on the calcium-activated chloride current (ICaCl) present in parotid acinar cells was studied using the patch clamp technique. Application of 1 mM of 8-(4-chlorophenylthio)adenosine 3':5'-cyclic monophosphate (CPT-cAMP), a permeable analog of cAMP, inhibited ICaCl only at positive potentials. This inhibition was partially abolished in cells dialyzed with 20 nM PKI 6-22 amide, a potent peptide that specifically inhibits PKA. Because cAMP is an activator of the CFTR Cl- channel, a known regulator of ICaCl, we also investigated if the inhibition of ICaCl was mediated by activation of CFTR. To test this idea, we added 1 mM CPT-cAMP to acinar cells isolated from knockout animals that do not express the CFTR channel. In these cells the cAMP effect was totally abolished. Thus, our data provide evidence that cAMP regulates ICaCl by a dual mechanism involving PKA and CFTR.
Perez-Cornejo
Patricia
P
Facultad de Medicina, Universidad Autonoma de San Luis Potosi, A. Obregón 64, San Luis Potosi, SLP 78000, Mexico. gperez@uaslp.mx
Arreola
Jorge
J
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000737:chemistry*; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism* / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D018345:Mice, Knockout; D010306:Parotid Gland / Q000166:cytology*; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000494:pharmacology; D013873:Thionucleotides / Q000737:chemistry
D002352:Carrier Proteins; D018118:Chloride Channels; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D013873:Thionucleotides; C094363:protein kinase inhibitor (6-22)-amide; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium