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 Huqi San-Evoked Rat Colonic Anion Secretion through Increasing CFTR Expression

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaowei Xue ◽  
Zhengming Shi ◽  
Wen Wang ◽  
Xiaotong Yu ◽  
Ping Feng ◽  
...  
Keyword(s):  
Protein Content ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Anion Secretion ◽  
Mrna Transcripts ◽  
And Function ◽  
Cystic Fibrosis Transmembrane

Huqi San (HQS) is a Chinese herbal preparation of eight medicinal herbs that promote diuresis, detoxification, blood circulation, and cholestasis. Defects in transporter expression and function can cause cholestasis and jaundice. However, the mechanism of the cholestasis underlying HQS effects, especially on the gastrointestinal tract ion secretion, has not been elucidated. Real-time RT-PCR and Western blotting were used to study the expression and localization of cystic fibrosis transmembrane conductance regulator (CFTR) andα-ENaC in rat alimentary tract, and then the effect of HQS on the ion transport in rat distal colon mucosa was investigated using the short-circuit current (ISC) technique. The results showed that pretreatment with HQS significantly enhanced mRNA transcripts and protein content of CFTR in liver and distal colon but notα-ENaC in alimentary organs. HQS increasesISCand decreases the transepithelial resistance. Pretreatment with epithelial Na+channel blocker did not affect theISCresponses elicited by HQS, but removal of extracellular Cl−or pretreatment with Cl−channel or Na+-K+-2Cl−cotransporter blocker inhibited HQS-elicitedISCresponses. These findings demonstrated that HQS, RA, and RP can stimulate Cl−secretion in the distal colon by increasing the mRNA transcripts and protein content of CFTR in liver and distal colon.

scholarly journals Infection by Toxoplasma gondii, a severe parasite in neonates and AIDS patients, causes impaired anion secretion in airway epithelia

2015 ◽  
Vol 112 (14) ◽  
pp. 4435-4440 ◽  
Author(s):  
Hong-Mei Guo ◽  
Jiang-Mei Gao ◽  
Yu-Li Luo ◽  
Yan-Zi Wen ◽  
Yi-Lin Zhang ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Toxoplasma Gondii ◽  
Infected Mouse ◽  
Inflammatory Responses ◽  
Short Circuit ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Airway Epithelia ◽  
Anion Secretion ◽  
Cystic Fibrosis Transmembrane

The airway epithelia initiate and modulate the inflammatory responses to various pathogens. The cystic fibrosis transmembrane conductance regulator-mediated Cl− secretion system plays a key role in mucociliary clearance of inhaled pathogens. We have explored the effects of Toxoplasma gondii, an opportunistic intracellular protozoan parasite, on Cl− secretion of the mouse tracheal epithelia. In this study, ATP-induced Cl− secretion indicated the presence of a biphasic short-circuit current (Isc) response, which was mediated by a Ca2+-activated Cl− channel (CaCC) and the cystic fibrosis transmembrane conductance regulator. However, the ATP-evoked Cl− secretion in T. gondii-infected mouse tracheal epithelia and the elevation of [Ca2+]i in T. gondii-infected human airway epithelial cells were suppressed. Quantitative reverse transcription–PCR revealed that the mRNA expression level of the P2Y2 receptor (P2Y2-R) increased significantly in T. gondii-infected mouse tracheal cells. This revealed the influence that pathological changes in P2Y2-R had on the downstream signal, suggesting that P2Y2-R was involved in the mechanism underlying T. gondii infection in airways. These results link T. gondii infection as well as other pathogen infections to Cl− secretion, via P2Y2-R, which may provide new insights for the treatment of pneumonia caused by pathogens including T. gondii.

Stimulation of chloride secretion by baicalein in isolated rat distal colon

2002 ◽  
Vol 282 (3) ◽  
pp. G508-G518 ◽  
Author(s):  
W. H. Ko ◽  
V. W. Y. Law ◽  
W. C. Y. Yip ◽  
G. G. L. Yue ◽  
C. W. Lau ◽  
...  
Keyword(s):  
Colonic Mucosa ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Chloride Secretion ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Ussing Chambers ◽  
Rat Distal Colon ◽  
Cystic Fibrosis Transmembrane

The effect of baicalein on mucosal ion transport in the rat distal colon was investigated in Ussing chambers. Mucosal addition of baicalein (1–100 μM) elicited a concentration-dependent short-circuit current ( I sc) response. The increase in I sc was mainly due to Cl−secretion. The presence of mucosal indomethacin (10 μM) significantly reduced both the basal and subsequent baicalein-evoked I sc responses. The baicalein-induced I sc were inhibited by mucosal application of diphenylamine-2-carboxylic acid (100 μM) and glibenclamide (500 μM) and basolateral application of chromanol 293B (30 μM), a blocker of KvLQT1 channels and Ba2+ ions (5 mM). Treatment of the colonic mucosa with baicalein elicited a threefold increase in cAMP production. Pretreating the colonic mucosa with carbachol (100 μM, serosal) but not thapsigargin (1 μM, both sides) abolished the baicalein-induced I sc. Addition of baicalein subsequent to forskolin induced a further increase in I sc. These results indicate that the baicalein evoked Cl− secretion across rat colonic mucosa, possibly via a cAMP-dependent pathway. However, the action of baicalein cannot be solely explained by its cAMP-elevating effect. Baicalein may stimulate Cl− secretion via a cAMP-independent pathway or have a direct effect on cystic fibrosis transmembrane conductance regulator.

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.

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.

PRO–CF–MED, Clinical Proof of concept for a RNA–targeting Oligonucleotide for a Cystic fibrosis–F508del MEDication, Horizon2020

Impact ◽  
2018 ◽  
Vol 2018 (3) ◽  
pp. 52-54
Author(s):  
Nicolas Lamontagne
Keyword(s):  
Cystic Fibrosis ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Rna Targeting ◽  
Threatening Condition ◽  
Life Threatening ◽  
Cftr Protein ◽  
Disease Modifying ◽  
Cystic Fibrosis Transmembrane ◽  
Specific Challenge

Cystic fibrosis (CF) is a progressive life–shortening disease caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene leading to a dysfunctional CFTR protein. The disease affects over 70,000 patients worldwide and while many mutations are known, the F508del mutation affects 90% of all patients. The absence of CFTR in the plasma membrane leads to a dramatic decrease in chloride efflux, resulting in viscous mucus that causes severe symptoms in vital organs like the lungs and intestines. For CF patients that suffer from the life threatening F508del mutation only palliative treatment exist. PRO–CF–MED addresses the specific challenge of this call by introducing the first disease modifying medication for the treatment of the CF patients with F508del mutation. The PRO–CF–MED project has been designed to assess the potential clinical efficacy of QR–010, an innovative disease modifying oligonucleotide–based treatment for F508del patients. Partners within PRO–CF–MED have generated very promising preclinical evidence for QR–010 which allows for further clinical assessment of QR–010 in clinical trials. PRO–CF–MED will enable the fast translation of QR–010 towards clinical practice and market authorisation. PRO–CF–MED has the potential to transform this life–threatening condition into a manageable one.

scholarly journals Progress in precision medicine in cystic fibrosis: a focus on CFTR modulator therapy

Breathe ◽  
2021 ◽  
Vol 17 (4) ◽  
pp. 210112
Author(s):  
Daniel H. Tewkesbury ◽  
Rebecca C. Robey ◽  
Peter J. Barry
Keyword(s):  
Cystic Fibrosis ◽  
Precision Medicine ◽  
Real World ◽  
Chloride Ion ◽  
Transmembrane Conductance Regulator ◽  
Therapeutic Approaches ◽  
Transmembrane Conductance ◽  
Cftr Protein ◽  
Cystic Fibrosis Transmembrane ◽  
Cftr Modulators

The genetic multisystem condition cystic fibrosis (CF) has seen a paradigm shift in therapeutic approaches within the past decade. Since the first clinical descriptions in the 1930s, treatment advances had focused on the downstream consequences of a dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR) chloride ion channel. The discovery of the gene that codes for CFTR and an understanding of the way in which different genetic mutations lead to disruption of normal CFTR function have led to the creation and subsequent licensing of drugs that target this process. This marks an important move towards precision medicine in CF and results from clinical trials and real-world clinical practice have been impressive. In this review we outline how CFTR modulator drugs restore function to the CFTR protein and the progress that is being made in this field. We also describe the real-world impact of CFTR modulators on both pulmonary and multisystem complications of CF and what this will mean for the future of CF care.

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