Fetal lung cell-derived matrix alters distal lung epithelial ion transport

1995 ◽  
Vol 268 (5) ◽  
pp. L762-L771 ◽  
Author(s):  
O. M. Pitkanen ◽  
A. K. Tanswell ◽  
H. M. O'Brodovich
Keyword(s):  
Epithelial Cells ◽  
Ion Transport ◽  
Short Circuit ◽  
Alveolar Epithelial Cells ◽  
Lung Epithelial Cells ◽  
Bathing Solution ◽  
Type I ◽  
Ussing Chambers ◽  
Lung Epithelial ◽  
Distal Lung

Extracellular matrix (ECM) synthesized by the fetal mesenchymal cells provides a supporting structure for the growing airways and is important for airway branching and in the differentiation of the primitive epithelium. We studied whether ECM, in addition to its structural role in lung interstitium, influences the ion transport of rat fetal distal lung epithelial cells (FDLE). FDLE monolayers were cultured on two different fetal mixed lung cell (MLC)-derived matrix preparations and studied in Ussing chambers. FDLE on MLC matrix had an increased resting equivalent short-circuit current (Ieq). Amiloride (10(-4) M apically) decreased the Ieq significantly in all the FDLE monolayers. The residual Ieq was significantly larger in FDLE grown on MLC matrix (increased by 150 and 80% under baseline and beta 2-agonist-stimulated conditions, respectively) than on control filters and filters coated with type I collagen, and type IV collagen, laminin, or fibronectin. The matrix produced by MLC isolated at an earlier gestational stage decreased the FDLE's sensitivity to amiloride. The increased amiloride-insensitive Ieq was only modestly affected by the Na+/K+/Cl- cotransport inhibitor bumetanide (10(-4) M basally) but was abolished when the [Cl-] of the bathing solution was reduced to 10 mM. These observations demonstrated that MLC elaborated ECM is able to change the nature of the ion transport of FDLE. ECM may be an important factor governing the ion transporting phenotype of fetal type II alveolar epithelial cells.

Modulation of sodium transport in fetal alveolar epithelial cells by oxygen and corticosterone

2003 ◽  
Vol 284 (2) ◽  
pp. L376-L385 ◽  
Author(s):  
Ulrich H. Thome ◽  
Ian C. Davis ◽  
Susie Vo Nguyen ◽  
Brent Jay Shelton ◽  
Sadis Matalon
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Alveolar Epithelial Cells ◽  
Lung Epithelial Cells ◽  
Ussing Chambers ◽  
Alveolar Epithelial ◽  
Lung Epithelial ◽  
Distal Lung ◽  
Postnatal Adaptation ◽  
Short Circuit Currents

Regulation of active Na+transport across fetal distal lung epithelial cells (FDLE) by corticosterone (CST), corticotropin-releasing hormone (CRH), and oxygen tension may be crucial for postnatal adaptation. FDLE isolated from 19-day rat fetuses (term: 22 days) were grown on permeable supports to confluent monolayers (duration 3 days) in 2.5, 5, 12, or 20% O2 with 5% CO2-balance N2 and mounted in Ussing chambers for measurement of short-circuit currents ( I sc). FDLE monolayers grown in 20% O2 had significantly higher levels of total I sc and of their amiloride-sensitive ( I amil) and ouabain-sensitive ( I ouab) components than hypoxic cells. Values (μA/cm2 ± SE) for 2.5–5% O2 and 20% O2 were, respectively, I sc5.3 ± 0.2 vs. 8.4 ± 0.3 ( P < 0.001), I amil 3.4 ± 0.2 vs. 4.3 ± 0.2 ( P < 0.01), and I ouab 3.4 ± 0.6 vs. 9.1 ± 0.6 ( P < 0.001). Addition of CST but not CRH to the culture medium at any O2concentration increased I amil. FDLE cells grown at 5% O2 expressed significantly lower levels of α-, β-, and γ-epithelial Na+ channel (ENaC), and of the α1-Na+-K+-ATPase, as determined by Western blotting. We conclude that higher O2concentrations increased total vectorial Na+ transport, and the function of Na+-K+-ATPase and apical amiloride-sensitive Na+ conductance, whereas CST only increased ENaC function.

pH-regulated chloride secretion in fetal lung epithelia

2000 ◽  
Vol 278 (6) ◽  
pp. L1248-L1255 ◽  
Author(s):  
Carol J. Blaisdell ◽  
Rebecca D. Edmonds ◽  
Xi-Tao Wang ◽  
Sandra Guggino ◽  
Pamela L. Zeitlin
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Fetal Lung ◽  
Chloride Secretion ◽  
Lung Epithelial Cells ◽  
Apical Surface ◽  
Ussing Chambers ◽  
Lung Fluid ◽  
Lung Epithelial ◽  
Distal Lung

The fetal lung actively transports chloride across the airway epithelium. ClC-2, a pH-activated chloride channel, is highly expressed in the fetal lung and is located on the apical surface of the developing respiratory epithelium. Our goal was to determine whether acidic pH could stimulate chloride secretion in fetal rat distal lung epithelial cells mounted in Ussing chambers. A series of acidic solutions stimulated equivalent short-circuit current ( I eq) from a baseline of 28 ± 4.8 (pH 7.4) to 70 ± 5 (pH 6.2), 114 ± 12.8 (pH 5.0), and 164 ± 19.2 (pH 3.8) μA/cm2. These changes in I eq were inhibited by 1 mM cadmium chloride and did not result in large changes in [3H]mannitol paracellular flux. Immunofluorescent detection by confocal microscopy revealed that ClC-2 is expressed along the luminal surface of polarized fetal distal lung epithelial cells. These data suggest that the acidic environment of the fetal lung fluid could activate chloride channels contributing to fetal lung fluid production and that the changes in I eqseen in these Ussing studies may be due to stimulation of ClC-2.

Inhibition of amiloride-sensitive sodium-channel activity in distal lung epithelial cells by nitric oxide

1998 ◽  
Vol 274 (3) ◽  
pp. L378-L387 ◽  
Author(s):  
Jin Wen Ding ◽  
John Dickie ◽  
Hugh O’Brodovich ◽  
Yutaka Shintani ◽  
Bijan Rafii ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Epithelial Cells ◽  
Cell Function ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Lung Epithelial Cells ◽  
Flufenamic Acid ◽  
Activated Macrophages ◽  
Lung Epithelial ◽  
Distal Lung

Distal lung epithelial cells (DLECs) play an active role in fluid clearance from the alveolus by virtue of their ability to actively transport Na+ from the alveolus to the interstitial space. The present study evaluated the ability of activated macrophages to modulate the bioelectric properties of DLECs. Low numbers of lipopolysaccharide (LPS)-treated macrophages were able to significantly reduce amiloride-sensitive short-circuit current ( I sc) without affecting total I sc or monolayer resistance. This was associated with a rise in the flufenamic acid-sensitive component of the I sc. The effect was reversed by the addition of N-monomethyl-l-arginine to the medium, implying a role for nitric oxide. We hypothesized that macrophages exerted their effect by expressing inducible nitric oxide synthase (iNOS) in DLECs. The products of LPS-treated macrophages increased the levels of iNOS protein and mRNA transcripts in DLECs as well as causing a rise in iNOS activity. Immunofluorescence microscopy of LPS-stimulated macrophage-DLEC cocultures with anti-nitrotyrosine antibodies provided evidence for the generation of peroxynitrite in macrophages but not in DLECs. These data indicate that activated macrophages in the lung may contribute to impaired resolution of acute respiratory distress syndrome and suggest a novel mechanism whereby nitric oxide might alter cell function by altering its ion-transporting phenotype.

Long-term terbutaline exposure stimulates α1-Na+-K+-ATPase expression at posttranscriptional level in rat fetal distal lung epithelial cells

2010 ◽  
Vol 298 (1) ◽  
pp. L96-L104 ◽  
Author(s):  
Muhammad S. Rahman ◽  
Shephali Gandhi ◽  
Gail Otulakowski ◽  
Wenming Duan ◽  
Aparna Sarangapani ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Atpase Activity ◽  
Apical Membrane ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Lung Epithelial Cells ◽  
Intracellular Camp ◽  
Adult Type ◽  
Lung Epithelial ◽  
Distal Lung

Transepithelial Na+ transport through epithelial Na+ channels (ENaC) on the apical membrane and Na+-K+-ATPase activity on the basolateral membrane of distal lung epithelial cells are critical for alveolar fluid clearance. Acute exposure to β-adrenergic agonists stimulates lung fluid clearance by increasing Na+ transport. We investigated the effects of chronic exposure to the β2-adrenergic agonist terbutaline on the transepithelial Na+ transport in rat fetal distal lung epithelia (FDLE). FDLE monolayers exposed to 10−4 M terbutaline for 48 h had significantly increased propanolol-blockable transepithelial total and amiloride-sensitive short-circuit current ( Isc); however, when these chronically exposed monolayers were acutely exposed to additional β-agonists and intracellular cAMP upregulators, there was no further increase in Isc. Monolayers exposed to terbutaline for >48 h had Isc similar to control cells. Ouabain-sensitive Na+-K+-ATPase activity was increased in 48-h terbutaline-exposed FDLE whose apical membranes were permeabilized with nystatin. In contrast, terbutaline did not increase amiloride-sensitive apical membrane Isc in FDLE whose basolateral membranes were permeabilized with nystatin. Terbutaline treatment did not affect α-, β-, or γ-ENaC mRNA or α-ENaC protein steady-state levels, but increased total cellular levels and rate of synthesis of α1-Na+-K+-ATPase protein in FDLE in the absence of any change in α1-Na+-K+-ATPase mRNA. Total cellular β1-Na+-K+-ATPase mRNA and protein levels were not affected by terbutaline. These data suggest that FDLE have different responses from adult type II epithelial cells when chronically exposed to terbutaline, and their increased transepithelial Na+ transport occurs via a posttranscriptional increase in α1-Na+-K+-ATPase expression.

cAMP regulation of Cl− and HCO 3 − secretion across rat fetal distal lung epithelial cells

2002 ◽  
Vol 282 (4) ◽  
pp. L650-L658 ◽  
Author(s):  
Ahmed Lazrak ◽  
Ulrich Thome ◽  
Carpantanto Myles ◽  
Janice Ware ◽  
Lan Chen ◽  
...  
Keyword(s):  
Short Circuit ◽  
Lung Epithelial Cells ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Anion Secretion ◽  
Ussing Chambers ◽  
Lung Epithelial ◽  
Cftr Protein ◽  
Distal Lung ◽  
Cystic Fibrosis Transmembrane

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 μA/cm2 and 1,018 ± 73 Ω · cm2, respectively (means ± SE; n = 12). Apical amiloride (10 μM) inhibited basal I sc by ∼50%. Subsequent addition of forskolin (10 μM) increased I sc from 3.9 ± 0.63 μA/cm2 to 7.51 ± 0.2 μA/cm2( n = 12). Basolateral bumetanide (100 μM) decreased forskolin-stimulated I sc from 7.51 ± 0.2 μA/cm2 to 5.62 ± 0.53, whereas basolateral 4,4′-dinitrostilbene-2,2′-disulfonate (5 mM), an inhibitor of HCO[Formula: see text] secretion, blocked the remaining I sc. Forskolin addition evoked currents of similar fractional magnitudes in symmetrical Cl−- or HCO[Formula: see text]-free solutions; however, no response was seen using HCO[Formula: see text]- 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[Formula: see text] secretion across rat FDLE cells mediated via CFTR.

scholarly journals The effects of P O2 upon transepithelial ion transport in fetal rat distal lung epithelial cells

2000 ◽  
Vol 524 (2) ◽  
pp. 539-547 ◽  
Author(s):  
S. J. Ramminger ◽  
D. L. Baines ◽  
R. E. Olver ◽  
S. M. Wilson
Keyword(s):  
Epithelial Cells ◽  
Ion Transport ◽  
Lung Epithelial Cells ◽  
Fetal Rat ◽  
Lung Epithelial ◽  
Distal Lung

scholarly journals P2Y2 receptor-mediated inhibition of ion transport in distal lung epithelial cells

1999 ◽  
Vol 128 (2) ◽  
pp. 293-300 ◽  
Author(s):  
S J Ramminger ◽  
A Collett ◽  
D L Baines ◽  
H Murphie ◽  
H L McAlroy ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Ion Transport ◽  
Lung Epithelial Cells ◽  
P2y2 Receptor ◽  
Lung Epithelial ◽  
Distal Lung

Ion transport properties of fetal sheep alveolar epithelial cells in monolayer culture

1996 ◽  
Vol 270 (6) ◽  
pp. L1008-L1016 ◽  
Author(s):  
G. J. Tessier ◽  
G. D. Lester ◽  
M. R. Langham ◽  
S. Cassin
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Alveolar Epithelial Cells ◽  
Sodium Absorption ◽  
Alveolar Type ◽  
Lung Epithelium ◽  
Fetal Sheep ◽  
Ussing Chambers ◽  
Apical Side ◽  
Distal Lung

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.

cAMP stimulates Na+ transport in rat fetal pneumocyte: involvement of a PTK- but not a PKA-dependent pathway

1999 ◽  
Vol 277 (4) ◽  
pp. L727-L736 ◽  
Author(s):  
Naomi Niisato ◽  
Yasushi Ito ◽  
Yoshinori Marunaka
Keyword(s):  
Epithelial Cells ◽  
Tyrosine Phosphorylation ◽  
Short Circuit ◽  
Lung Epithelial Cells ◽  
Cell Shrinkage ◽  
Inhibitory Peptide ◽  
Stimulatory Action ◽  
Lung Epithelial ◽  
Distal Lung ◽  
Dependent Pathway

To study a cAMP-mediated signaling pathway in the regulation of amiloride-sensitive Na+ transport in rat fetal distal lung epithelial cells, we measured an amiloride-sensitive short-circuit current (Na+ transport). Forskolin, which increases the cytosolic cAMP concentration, stimulated the Na+ transport. Forskolin also activated cAMP-dependent protein kinase (PKA). A β-adrenergic agonist and cAMP mimicked the forskolin action. PKA inhibitors KT-5720, H-8, and myristoylated PKA-inhibitory peptide amide-(14—22) did not influence the forskolin action. These results suggest that forskolin stimulates Na+ transport through a PKA-independent pathway. Furthermore, forskolin increased tyrosine phosphorylation of ∼70- to 80-, ∼97-, and ∼110- to 120-kDa proteins. Protein tyrosine kinase (PTK) inhibitors (tyrphostin A23 and genistein) abolished the forskolin action. Moreover, 5-nitro-2-(3-phenylpropylamino)benzoate (a Cl−-channel blocker) prevented the stimulatory action of forskolin on Na+ transport via abolishment of the forskolin-induced cell shrinkage and tyrosine phosphorylation. Based on these results, we conclude that forskolin (and cAMP) stimulates Na+ transport in a PTK-dependent but not a PKA-dependent pathway by causing cell shrinkage, which activates PTK in rat fetal distal lung epithelial cells.

scholarly journals TRIM72 modulates caveolar endocytosis in repair of lung cells

2016 ◽  
Vol 310 (5) ◽  
pp. L452-L464 ◽  
Author(s):  
Nagaraja Nagre ◽  
Shaohua Wang ◽  
Thomas Kellett ◽  
Ragu Kanagasabai ◽  
Jing Deng ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Cell Injury ◽  
Alveolar Epithelial Cells ◽  
Lung Epithelial Cells ◽  
Functional Domain ◽  
Physical Interaction ◽  
Type I ◽  
Alveolar Epithelial ◽  
Lung Epithelial

Alveolar epithelial and endothelial cell injury is a major feature of the acute respiratory distress syndrome, in particular when in conjunction with ventilation therapies. Previously we showed [Kim SC, Kellett T, Wang S, Nishi M, Nagre N, Zhou B, Flodby P, Shilo K, Ghadiali SN, Takeshima H, Hubmayr RD, Zhao X. Am J Physiol Lung Cell Mol Physiol 307: L449–L459, 2014.] that tripartite motif protein 72 (TRIM72) is essential for amending alveolar epithelial cell injury. Here, we posit that TRIM72 improves cellular integrity through its interaction with caveolin 1 (Cav1). Our data show that, in primary type I alveolar epithelial cells, lack of TRIM72 led to significant reduction of Cav1 at the plasma membrane, accompanied by marked attenuation of caveolar endocytosis. Meanwhile, lentivirus-mediated overexpression of TRIM72 selectively increases caveolar endocytosis in rat lung epithelial cells, suggesting a functional association between these two. Further coimmunoprecipitation assays show that deletion of either functional domain of TRIM72, i.e., RING, B-box, coiled-coil, or PRY-SPRY, abolishes the physical interaction between TRIM72 and Cav1, suggesting that all theoretical domains of TRIM72 are required to forge a strong interaction between these two molecules. Moreover, in vivo studies showed that injurious ventilation-induced lung cell death was significantly increased in knockout (KO) TRIM72KO and Cav1KO lungs compared with wild-type controls and was particularly pronounced in double KO mutants. Apoptosis was accompanied by accentuation of gross lung injury manifestations in the TRIM72KO and Cav1KO mice. Our data show that TRIM72 directly and indirectly modulates caveolar endocytosis, an essential process involved in repair of lung epithelial cells through removal of plasma membrane wounds. Given TRIM72's role in endomembrane trafficking and cell repair, we consider this molecule an attractive therapeutic target for patients with injured lungs.

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