Cytosolic [Cl-] regulates Na+ absorption in fetal alveolar epithelium?: roles of cAMP and Cl- channels.
We studied the regulatory mechanism of Na+ absorption in fetal distal lung epithelium (FDLE), using patch clamp and single cell imaging techniques. A beta 2-agonist activated a 28 pS non-selective cation channel (NSCC) by: 1) producing a dependency of the NSCC activity on the cytosolic [Cl-] ([Cl-]c); 2) inducing a reduction in the [Cl-]c from 45 to 25 mM which directly activated the beta 2-treated NSCC. The beta 2-agonist-induced decrease in [Cl-]c was caused by activation of Ca(2+)-activated K+ channel and cAMP-activated Cl- channel. A development of the [Cl-]c-dependency and a reduction in [Cl-]c act as a second messenger of the beta 2 agonist signal transduction pathway in this Na+ transporting epithelium.
Marunaka
Y
Y
Medical Research Council Group in Lung Development, Hospital for Sick Children Research Institute, Toronto, Ontario, Canada.
Nakahari
T
T
Tohda
H
H
D000200:Action Potentials / Q000187:drug effects; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D018118:Chloride Channels / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology*; D004848:Epithelium / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D051381:Rats; D017208:Rats, Wistar; D013726:Terbutaline / Q000494:pharmacology
D018118:Chloride Channels; D002712:Chlorides; D000584:Amiloride; D000242:Cyclic AMP; D013726:Terbutaline