title: Ion transport properties of fetal sheep alveolar epithelial cells in monolayer culture.
abstract: Alveolar type II cells were isolated from late-term fetal sheep to investigate ion transport across fetal distal lung epithelium. In Ussing chambers, basal transepithelial potential difference (PD; reference apical side), equivalent short-circuit current (Ieq), and resistance were -0.10 +/- 0.05 mV, 0.10 +/- 0.08 microA/cm2, and 821.5 +/- 38.8 omega .cm2, respectively. Epinephrine (100 nM) increased PD from -0.13 +/- 0.19 to -1.37 +/- 0.20 mV and Ieq from 0.18 +/- 0.26 to 1.47 +/- 0.28 microA/cm2. Propranolol (100 nM) inhibited responses to epinephrine. Forskolin (10 microM) increased PD to -0.81 +/- 0.08 mV and Ieq to 1.02 +/- 0.12 microA/cm2. Mucosal amiloride (200 microM) and serosal bumetanide (10 microM) decreased the forskolin-stimulated PD by 23.42 +/- 4.73 and 25.57 +/- 3.9%, respectively. We conclude that in fetal sheep distal lung epithelium amiloride-inhibitable sodium absorption and bumetanide-sensitive chloride secretion are stimulated by forskolin and that epinephrine effects on ion transport are mediated by beta-adrenergic receptors.
authors.affiliation: Department of Physiology, College of Medicine, University of Florida, Gainesville 32610, USA.
authors.forename: G J
authors.initials: GJ
authors.lastname: Tessier
authors.forename: G D
authors.initials: GD
authors.lastname: Lester
authors.forename: M R
authors.initials: MR
authors.lastname: Langham
authors.forename: S
authors.initials: S
authors.lastname: Cassin
mesh_terms: D000042:Absorption; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D004553:Electric Conductivity; D004837:Epinephrine / Q000494:pharmacology; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005333:Fetus / Q000378:metabolism; D007477:Ions; D011650:Pulmonary Alveoli / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D012756:Sheep / Q000196:embryology; D012964:Sodium / Q000378:metabolism
chemical_list: D002712:Chlorides; D007477:Ions; D002034:Bumetanide; D005576:Colforsin; D000584:Amiloride; D012964:Sodium; D004837:Epinephrine