scholarly journals Apical adenosine regulates basolateral Ca2+-activated potassium channels in human airway Calu-3 epithelial cells

2008 ◽  
Vol 294 (6) ◽  
pp. C1443-C1453 ◽  
Author(s):  
Dong Wang ◽  
Ying Sun ◽  
Wei Zhang ◽  
Pingbo Huang
Keyword(s):  
Epithelial Cells ◽  
Adenosine Receptors ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Specific Inhibitor ◽  
Short Circuit Current ◽  
Airway Epithelial Cells ◽  
Intracellular Camp ◽  
Anion Secretion ◽  
Human Airway

In airway epithelial cells, apical adenosine regulates transepithelial anion secretion by activation of apical cystic fibrosis transmembrane conductance regulator (CFTR) via adenosine receptors and cAMP/PKA signaling. However, the potent stimulation of anion secretion by adenosine is not correlated with its modest intracellular cAMP elevation, and these uncorrelated efficacies have led to the speculation that additional signaling pathways may be involved. Here, we showed that mucosal adenosine-induced anion secretion, measured by short-circuit current ( Isc), was inhibited by the PLC-specific inhibitor U-73122 in the human airway submucosal cell line Calu-3. In addition, the Isc was suppressed by BAPTA-AM (a Ca2+ chelator) and 2-aminoethoxydiphenyl borate (2-APB; an inositol 1,4,5-trisphosphate receptor blocker), but not by PKC inhibitors, suggesting the involvement of PKC-independent PLC/Ca2+ signaling. Ussing chamber and patch-clamp studies indicated that the adenosine-induced PLC/Ca2+ signaling stimulated basolateral Ca2+-activated potassium (KCa) channels predominantly via A2B adenosine receptors and contributed substantially to the anion secretion. Thus, our data suggest that apical adenosine activates contralateral K+ channels via PLC/Ca2+ and thereby increases the driving force for transepithelial anion secretion, synergizing with its modulation of ipsilateral CFTR via cAMP/PKA. Furthermore, the dual activation of CFTR and KCa channels by apical adenosine resulted in a mixed secretion of chloride and bicarbonate, which may alter the anion composition in the secretion induced by secretagogues that elicit extracellular ATP/adenosine release. Our findings provide novel mechanistic insights into the regulation of anion section by adenosine, a key player in the airway surface liquid homeostasis and mucociliary clearance.

The rescue of F508del-CFTR by elexacaftor/tezacaftor/ivacaftor (Trikafta) in human airway epithelial cells is underestimated due to the presence of ivacaftor

2021 ◽  
pp. 2100671
Author(s):  
Frédéric Becq ◽  
Sandra Mirval ◽  
Thomas Carrez ◽  
Manuella Lévêque ◽  
Arnaud Billet ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Triple Combination Therapy ◽  
Whole Cell Patch Clamp ◽  
Membrane Location ◽  
And Function

Trikafta, currently the leading therapeutic in Cystic Fibrosis (CF), has demonstrated a real clinical benefit. This treatment is the triple combination therapy of two folding correctors elexacaftor/tezacaftor (VX445/VX661) plus the gating potentiator ivacaftor (VX770). In this study, our aim was to compare the properties of F508del-CFTR in cells treated with either lumacaftor (VX809), tezacaftor, elexacaftor, elexacaftor/tezacaftor with or without ivacaftor. We studied F508del-CFTR function, maturation and membrane localisation by Ussing chamber and whole-cell patch clamp recordings, Western blot and immunolocalization experiments. With human primary airway epithelial cells and the cell lines CFBE and BHK expressing F508del, we found that, whereas the combination elexacaftor/tezacaftor/ivacaftor was efficient in rescuing F508del-CFTR abnormal maturation, apical membrane location and function, the presence of ivacaftor limits these effects. The basal F508del-CFTR short-circuit current was significantly increased by elexacaftor/tezacaftor/ivacaftor and elexacaftor/tezacaftor compared to other correctors and non-treated cells, an effect dependent on ivacaftor and cAMP. These results suggest that the level of the basal F508del-CFTR current might be a marker for correction efficacy in CF cells. When cells were treated with ivacaftor combined to any correctors, the F508del-CFTR current was unresponsive to the subsequently acute addition of ivacaftor unlike the CFTR potentiators genistein and Cact-A1 which increased elexacaftor/tezacaftor/ivacaftor and elexacaftor/tezacaftor-corrected F508del-CFTR currents. These findings show that ivacaftor reduces the correction efficacy of Trikafta. Thus, combining elexacaftor/tezacaftor with a different potentiator might improve the therapeutic efficacy for treating CF patients.

scholarly journals Naringenin Regulates CFTR Activation and Expression in Airway Epithelial Cells

2017 ◽  
Vol 44 (3) ◽  
pp. 1146-1160 ◽  
Author(s):  
Rui Shi ◽  
Zi-Ting Xiao ◽  
Yi-Jun Zheng ◽  
Yi-Lin Zhang ◽  
Jia-Wen Xu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
The Elderly ◽  
Airway Epithelial Cells ◽  
Intracellular Camp ◽  
Transmembrane Conductance Regulator ◽  
Airway Epithelial ◽  
Camp Content ◽  
Basolateral Side

Background/Aims: Sputum symptoms are commonly seen in the elderly. This study aimed to identify an efficacious expectorant treatment stratagem through evaluating the secretion-promoting activation and cystic fibrosis transmembrane conductance regulator (CFTR) expression of the bioactive herbal monomer naringenin. Methods: Vectorial Cl- transport was determined by measuring short-circuit current (ISC) in rat airway epithelium. cAMP content was measured by ELISA in primary cultured epithelial cells and Calu-3 cells. CFTR expression in Calu-3 cells was determined by qPCR. Results: Addition of naringenin to the basolateral side of the rat airway led to a concentration-dependent sustained increase in ISC. The current was suppressed when exposed to Cl–-free solution or by bumetanide, BaCl2, and DPC but not by DIDS and IBMX. Forskolin-induced ISC increase and CFTRinh-172/MDL-12330A-induced ISC inhibition were not altered by naringenin. Intracellular cAMP content was significantly increased by naringenin. With lipopolysaccharide stimulation, CFTR expression was significantly reduced, and naringenin dose-dependently enhanced CFTR mRNA expression. Conclusion: These results demonstrate that naringenin has the ability to stimulate Cl- secretion, which is mediated by CFTR through a signaling pathway by increasing cAMP content. Moreover, naringenin can increase CFTR expression when organism CFTR expression is seriously hampered. Our data suggest a potentially effective treatment strategy for sputum.

scholarly journals Carvedilol binding to β2-adrenergic receptors inhibits CFTR-dependent anion secretion in airway epithelial cells

2016 ◽  
Vol 310 (1) ◽  
pp. L50-L58 ◽  
Author(s):  
Elizabeth R. Peitzman ◽  
Nathan A. Zaidman ◽  
Peter J. Maniak ◽  
Scott M. O'Grady
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Inhibitory Effect ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Protein Activation ◽  
Anion Secretion ◽  
G Protein Activation ◽  
Channel Expression

Carvedilol functions as a nonselective β-adrenergic receptor (AR)/α1-AR antagonist that is used for treatment of hypertension and heart failure. Carvedilol has been shown to function as an inverse agonist, inhibiting G protein activation while stimulating β-arrestin-dependent signaling and inducing receptor desensitization. In the present study, short-circuit current ( Isc) measurements using human airway epithelial cells revealed that, unlike β-AR agonists, which increase Isc, carvedilol decreases basal and 8-(4-chlorophenylthio)adenosine 3′,5′-cyclic monophosphate-stimulated current. The decrease in Isc resulted from inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR). The carvedilol effect was abolished by pretreatment with the β2-AR antagonist ICI-118551, but not the β1-AR antagonist atenolol or the α1-AR antagonist prazosin, indicating that its inhibitory effect on Isc was mediated through interactions with apical β2-ARs. However, the carvedilol effect was blocked by pretreatment with the microtubule-disrupting compound nocodazole. Furthermore, immunocytochemistry experiments and measurements of apical CFTR expression by Western blot analysis of biotinylated membranes revealed a decrease in the level of CFTR protein in monolayers treated with carvedilol but no significant change in monolayers treated with epinephrine. These results demonstrate that carvedilol binding to apical β2-ARs inhibited CFTR current and transepithelial anion secretion by a mechanism involving a decrease in channel expression in the apical membrane.

scholarly journals A Ba2+-resistant, acid-sensitive K+ conductance in Na+-absorbing H441 human airway epithelial cells

2007 ◽  
Vol 292 (5) ◽  
pp. L1304-L1312 ◽  
Author(s):  
Sarah K. Inglis ◽  
Sean G. Brown ◽  
Maree J. Constable ◽  
Niall McTavish ◽  
Richard E. Olver ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Inhibitory Effect ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Human Airway ◽  
K2p Channels ◽  
Human Airway Epithelial Cells

By analysis of whole cell membrane currents in Na+-absorbing H441 human airway epithelial cells, we have identified a K+ conductance ( GK) resistant to Ba2+ but sensitive to bupivacaine or extracellular acidification. In polarized H441 monolayers, we have demonstrated that bupivacaine, lidocaine, and quinidine inhibit basolateral membrane K+ current ( IBl) whereas Ba2+ has only a weak inhibitory effect. IBl was also inhibited by basolateral acidification, and, although subsequent addition of bupivacaine caused a further fall in IBl, acidification had no effect after bupivacaine, demonstrating that cells grown under these conditions express at least two different bupivacaine-sensitive K+ channels, only one of which is acid sensitive. Basolateral acidification also inhibited short-circuit current ( ISC), and basolateral bupivacaine, lidocaine, quinidine, and Ba2+ inhibited ISC at concentrations similar to those needed to inhibit IBl, suggesting that the K+ channels underlying IBl are part of the absorptive mechanism. Analyses using RT-PCR showed that mRNA encoding several two-pore domain K+ (K2P) channels was detected in cells grown under standard conditions (TWIK-1, TREK-1, TASK-2, TWIK-2, KCNK-7, TASK-3, TREK-2, THIK-1, and TALK-2). We therefore suggest that K2P channels underlie GK in unstimulated cells and so maintain the driving force for Na+ absorption. Since this ion transport process is vital to lung function, K2P channels thus play an important but previously undocumented role in pulmonary physiology.

scholarly journals Prostaglandin E2 mediates proliferation and chloride secretion in ADPKD cystic renal epithelia

2012 ◽  
Vol 303 (10) ◽  
pp. F1425-F1434 ◽  
Author(s):  
Yu Liu ◽  
Madhumitha Rajagopal ◽  
Kim Lee ◽  
Lorenzo Battini ◽  
Daniel Flores ◽  
...  
Keyword(s):  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Cell Number ◽  
Flufenamic Acid ◽  
Prostaglandin E ◽  
Intracellular Camp ◽  
Ep4 Receptor ◽  
Autosomal Dominant Polycystic Kidney

Prostaglandin E2 (PGE2) contributes to cystogenesis in genetically nonorthologous models of autosomal dominant polycystic kidney disease (ADPKD). However, it remains unknown whether PGE2 induces the classic features of cystic epithelia in genetically orthologous models of ADPKD. We hypothesized that, in ADPKD epithelia, PGE2 induces proliferation and chloride (Cl−) secretion, two archetypal phenotypic features of ADPKD. To test this hypothesis, proliferation and Cl− secretion were measured in renal epithelial cells deficient in polycystin-1 (PC-1). PC-1-deficient cells increased in cell number (proliferated) faster than PC-1-replete cells, and this proliferative advantage was abrogated by cyclooxygenase inhibition, indicating a role for PGE2 in cell proliferation. Exogenous administration of PGE2 increased proliferation of PC-1-deficient cells by 38.8 ± 5.2% ( P < 0.05) but inhibited the growth of PC-1-replete control cells by 49.4 ± 1.9% ( P < 0.05). Next, we tested whether PGE2-specific E prostanoid (EP) receptor agonists induce intracellular cAMP and downstream β-catenin activation. PGE2 and EP4 receptor agonism (TCS 2510) increased intracellular cAMP concentration and the abundance of active β-catenin in PC-1-deficient cells, suggesting a mechanism for PGE2-mediated proliferation. Consistent with this hypothesis, antagonizing EP4 receptors reverted the growth advantage of PC-1-deficient cells, implicating a central role for the EP4 receptor in proliferation. To test whether PGE2-dependent Cl− secretion is also enhanced in PC-1-deficient cells, we used an Ussing chamber to measure short-circuit current ( Isc). Addition of PGE2 induced a fivefold higher increase in Isc in PC-1-deficient cells compared with PC-1-replete cells. This PGE2-induced increase in Isc in PC-1-deficient cells was blocked by CFTR-172 and flufenamic acid, indicating that PGE2 activates CFTR and calcium-activated Cl− channels. In conclusion, PGE2 activates aberrant signaling pathways in PC-1-deficient epithelia that contribute to the proliferative and secretory phenotype characteristic of ADPKD and suggests a therapeutic role for PGE2 inhibition and EP4 receptor antagonism.

scholarly journals Regulation of electrolyte transport across cultured endometrial epithelial cells by prolactin

2008 ◽  
Vol 197 (3) ◽  
pp. 575-582 ◽  
Author(s):  
Chatsri Deachapunya ◽  
Sutthasinee Poonyachoti ◽  
Nateetip Krishnamra
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Disulfonic Acid ◽  
Maximum Effect ◽  
Channel Blockers ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Anion Secretion ◽  
Endometrial Epithelial Cells

The effect of prolactin (PRL) on ion transport across the porcine glandular endometrial epithelial cells was studied in primary cell culture using the short-circuit current technique. Addition of 1 μg/ml PRL either to the apical solution or to the basolateral solution produced a peak followed by a sustained increase in Isc, but with a lesser response when PRL was added apically. Basolateral addition of PRL increased the Isc in a concentration-dependent manner with a maximum effect at 1 μg/ml and an effective concentration value of 120 ng/ml. The PRL-stimulated Isc was significantly reduced by pretreatment with an apical addition of 5-nitro-2-(3-phenylpropylamino) benzoic acid (200 μM), diphenylamine-2-carboxylic acid (1 mM) or 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (200 μM), Cl− channel blockers, but not by amiloride (10 μM), a Na+ channel blocker. In addition, pretreatment with bumetanide (200 μM), a Na+–K+–2Cl− cotransporter inhibitor, in the basolateral solution significantly reduced the PRL-stimulated Isc. Replacement of Cl− or in the bathing solutions also decreased the Isc response to PRL. Pretreatment of the monolayer with AG490 (50 μM), an inhibitor of JAK2 activity significantly inhibited the PRL-induced increase in Isc. Western blot analysis of the porcine endometrial epithelial cells revealed the presence of short isoform of PRL receptor (PRLR-S) that could be regulated by 17β-estradiol. The results of this investigation showed that PRL acutely stimulated anion secretion across the porcine endometrial epithelial cells possibly through PRLR-S present in both apical and basolateral membranes. The PRL response appeared to be mediated by the JAK2-dependent pathway.

NH2-terminal modification of a channel-forming peptide increases capacity for epithelial anion secretion

2001 ◽  
Vol 280 (3) ◽  
pp. C451-C458 ◽  
Author(s):  
James R. Broughman ◽  
Kathy E. Mitchell ◽  
Roger L. Sedlacek ◽  
Takeo Iwamoto ◽  
John M. Tomich ◽  
...  
Keyword(s):  
Therapeutic Potential ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Glycine Receptor ◽  
Short Circuit Current ◽  
Disulfonic Acid ◽  
Α Subunit ◽  
Anion Secretion ◽  
Anion Conductance ◽  
Selective Channel

A synthetic, channel-forming peptide, derived from the α-subunit of the glycine receptor (M2GlyR), has been synthesized and modified by adding four lysine residues to the NH2 terminus (N-K4-M2GlyR). In Ussing chamber experiments, apical N-K4-M2GlyR (250 μM) increased transepithelial short-circuit current ( I sc) by 7.7 ± 1.7 and 10.6 ± 0.9 μA/cm2 in Madin-Darby canine kidney and T84 cell monolayers, respectively; these values are significantly greater than those previously reported for the same peptide modified by adding the lysines at the COOH terminus (Wallace DP, Tomich JM, Iwamoto T, Henderson K, Grantham JJ, and Sullivan LP. Am J Physiol Cell Physiol 272: C1672–C1679, 1997). N-K4-M2GlyR caused a concentration-dependent increase in I sc ( k [1/2] = 190 μM) that was potentiated two- to threefold by 1-ethyl-2-benzimidazolinone. N-K4-M2GlyR-mediated increases in I sc were insensitive to changes in apical cation species. Pharmacological inhibitors of endogenous Cl− conductances [glibenclamide, diphenylamine-2-dicarboxylic acid, 5-nitro-2-(3-phenylpropylamino)benzoic acid, 4,4′-dinitrostilben-2,2′-disulfonic acid, indanyloxyacetic acid, and niflumic acid] had little effect on N-K4-M2GlyR-mediated I sc. Whole cell membrane patch voltage-clamp studies revealed an N-K4-M2GlyR-induced anion conductance that exhibited modest outward rectification and modest time- and voltage-dependent activation. Planar lipid bilayer studies yielded results indicating that N-K4-M2GlyR forms a 50-pS anion conductance with a k [1/2] for Cl−of 290 meq. These results indicate that N-K4-M2GlyR forms an anion-selective channel in epithelial monolayers and shows therapeutic potential for the treatment of hyposecretory disorders such as cystic fibrosis.

Intracellular Ca2+ and regulation of ion transport across rabbit Clara cells

1992 ◽  
Vol 263 (1) ◽  
pp. L122-L127
Author(s):  
M. R. Van Scott ◽  
A. M. Paradiso
Keyword(s):  
Epithelial Cells ◽  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Airway Epithelial Cells ◽  
Clara Cell ◽  
Bathing Solution ◽  
Airway Epithelial ◽  
Clara Cells ◽  
Tracheal Cell

We investigated whether Ca2+ was involved in regulation of ion transport across rabbit distal airway epithelial cells by studying the effects that elevation of intracellular Ca2+ (Cai) had on the bioelectric properties of nonciliated bronchiolar (Clara) cell epithelia in culture. Exposure of Clara cells to 5 x 10(-7) M ionomycin increased Cai concentration and transepithelial short-circuit current (Isc). Changing extracellular Ca2+ concentration in the presence of ionomycin demonstrated that changes in Isc paralleled changes in Cai. Another ionophore, 4-bromo-A23187, also increased Cai and Isc. Ionomycin-induced changes in Isc were insensitive to amiloride and were inhibited greater than 50% by pretreating the cells with bumetanide or substituting gluconate for Cl- in the bathing solution. Bradykinin and carbachol, which increased Cai and caused an increase in Isc across tracheal cell cultures, had no effect on Cai or Isc in Clara cell preparations. These results support the hypothesis that changes in Cai are linked to regulation of Cl- secretion across bronchiolar epithelial cells, but physiological regulators of Cai in Clara cells remain to be defined.

Mast cells in the regulation of intestinal electrolyte transport

1986 ◽  
Vol 251 (2) ◽  
pp. G253-G262 ◽  
Author(s):  
D. A. Russell
Keyword(s):  
Mast Cells ◽  
Ion Transport ◽  
Trichinella Spiralis ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Antigen Challenge ◽  
Intracellular Camp ◽  
Camp Content ◽  
Ionic Basis

Experiments were performed to determine the ionic basis and physiological messengers of transepithelial ion transport alterations (short-circuit current, Isc) measured during the induction of intestinal anaphylaxis in an Ussing chamber. Antigens derived from Trichinella spiralis, an intestinal parasite, were used to challenge jejunal tissue from guinea pigs immunized by infection with the parasite. Histamine (10(-4) M) caused an increased in Isc that was similar to that induced by antigen. Diphenhydramine (10(-5) M) inhibited the epithelial electrical responses to histamine by 100% and to antigen by 60-70%. Indomethacin (10(-5) M), in combination with diphenhydramine, completely inhibited the antigen-induced rise in Isc. Furosemide (10(-4) M) caused 50-60% inhibition of the increase in Isc induced by antigen and histamine. Antigen challenge of isolated enterocytes did not alter intracellular cAMP content. However, antigen challenge of jejunal segments in which epithelial cells were in contact with sensitized mast cells increased mucosal cAMP content. These results suggest that electrogenic Cl- secretion, mediated in part by cAMP, contributes to antigen-induced jejunal ion transport changes and that histamine and prostaglandins are involved in eliciting these epithelial responses.

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