Bioelectric properties of cultured epithelial monolayers from distal lung of 18-day fetal rat.
In vivo studies of fetal sheep suggest that the liquid present in the lumen of the lung throughout fetal life is derived from Cl- secretion by the pulmonary epithelium. Monolayer preparations of enriched epithelial cells from distal fetal rat (18-day gestation) lung, grown in serum-free media, were histologically similar to acinar (prealveolar) structures of fresh tissue. In Ussing chambers, basal transepithelial potential difference (PD), calculated equivalent short-circuit current (Ieq), and transepithelial resistance (R) were 4.4 +/- 0.3 mV (matrix positive), 35.6 +/- 1.6 microA/cm2, and 120.0 +/- 4.0 omega cm2, respectively. Ouabain (10(-3) M) eliminated 57% of basal Ieq within 30 min, amiloride (10(-4) M) induced a 13% fall in Ieq, and phlorizin (10(-4) M) had no effect on bioelectric properties. Diphenylamine-2-carboxylate (DPC, 3 x 10(-3) M) inhibited Ieq by 50%. Bumetanide had no effect on baseline bioelectric parameters. The hyperpolarization that accompanied apical or bilateral replacement of Cl- and was enhanced by terbutaline suggested an apical Cl- permselectivity. Effects of Na+ replacement on amiloride-pretreated monolayers were consistent with Na(+)-dependent Cl- secretion or amiloride-insensitive pathways. Under these growth conditions, this preparation exhibits bioelectric characteristics that are compatible with Cl- secretion and Na+ absorption. The mechanism of Cl- secretion may be similar to that of airways but is uniquely bumetanide insensitive.
Barker
P M
PM
Department of Medicine, University of North Carolina, Chapel Hill 27599-7020.
Stiles
A D
AD
Boucher
R C
RC
Gatzy
J T
JT
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D004594:Electrophysiology; D005333:Fetus / Q000502:physiology*; D008168:Lung / Q000166:cytology / Q000196:embryology* / Q000502:physiology; D008854:Microscopy, Electron; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000378:metabolism; D013726:Terbutaline / Q000494:pharmacology; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D002712:Chlorides; D062367:ortho-Aminobenzoates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010042:Ouabain; C001209:fenamic acid; D012964:Sodium; D013726:Terbutaline; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid