cAMP regulation of Cl(-) and HCO(-)(3) secretion across rat fetal distal lung epithelial cells.
We isolated and cultured fetal distal lung epithelial (FDLE) cells from 17- to 19-day rat fetuses and assayed for anion secretion in Ussing chambers. With symmetrical Ringer solutions, basal short-circuit currents (I(sc)) and transepithelial resistances were 7.9 +/- 0.5 microA/cm(2) and 1,018 +/- 73 Omega.cm(2), respectively (means +/- SE; n = 12). Apical amiloride (10 microM) inhibited basal I(sc) by approximately 50%. Subsequent addition of forskolin (10 microM) increased I(sc) from 3.9 +/- 0.63 microA/cm(2) to 7.51 +/- 0.2 microA/cm(2) (n = 12). Basolateral bumetanide (100 microM) decreased forskolin-stimulated I(sc) from 7.51 +/- 0.2 microA/cm(2) to 5.62 +/- 0.53, whereas basolateral 4,4'-dinitrostilbene-2,2'-disulfonate (5 mM), an inhibitor of HCO secretion, blocked the remaining I(sc). Forskolin addition evoked currents of similar fractional magnitudes in symmetrical Cl(-)- or HCO(-)(3)-free solutions; however, no response was seen using HCO(-)(3)- and Cl(-)-free solutions. The forskolin-stimulated I(sc) was inhibited by glibenclamide but not apical DIDS. Glibenclamide also blocked forskolin-induced I(sc) across monolayers having nystatin-permeablized basolateral membranes. Immunolocalization studies were consistent with the expression of cystic fibrosis transmembrane conductance regulator (CFTR) protein in FDLE cells. In aggregate, these findings indicate the presence of cAMP-activated Cl(-) and HCO(-)(3) secretion across rat FDLE cells mediated via CFTR.
Lazrak
Ahmed
A
Department of Anesthesiology, University of Alabama at Birmingham, 619 19th Street S., Birmingham, AL 35233, USA.
Thome
Ulrich
U
Myles
Carpantanto
C
Ware
Janice
J
Chen
Lan
L
Venglarik
Charles J
CJ
Matalon
Sadis
S
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002034:Bumetanide / Q000494:pharmacology; D016764:Cell Polarity / Q000502:physiology; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000032:analysis / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology; D004847:Epithelial Cells / Q000737:chemistry / Q000378:metabolism; D015633:Extravascular Lung Water / Q000378:metabolism; D007150:Immunohistochemistry; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009761:Nystatin / Q000494:pharmacology; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism*; D013267:Stilbenes / Q000494:pharmacology
D001639:Bicarbonates; D002712:Chlorides; D004232:Diuretics; D007476:Ionophores; D013267:Stilbenes; D002034:Bumetanide; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D009761:Nystatin; D005576:Colforsin; C022306:4,4'-dinitro-2,2'-stilbenedisulfonic acid; D000584:Amiloride; D000242:Cyclic AMP