Evidence that prostaglandin E2 stimulates chloride secretion in cultured A6 renal epithelial cells

1986 ◽  
Vol 250 (3) ◽  
pp. F511-F515 ◽  
Author(s):  
R. Keeler ◽  
N. L. Wong
Keyword(s):  
Epithelial Cells ◽  
Prostaglandin E2 ◽  
Short Circuit ◽  
Basal Medium ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Apical Surface ◽  
Renal Epithelial Cells ◽  
Apical Side ◽  
Net Flux

The effects of prostaglandin E2 (PGE2) on the transport of sodium and chloride were studied in cultured A6 renal epithelial cells. PGE2 on the basolateral but not the apical surface increased transmonolayer short-circuit current (Isc) and conductance. These changes could not be inhibited with amiloride or furosemide in the apical medium. Flux measurements showed that although Isc and net flux of sodium were equal in unstimulated cells, after addition of PGE2 the current increased with no corresponding changes in bidirectional or net flux of sodium. Immersing the cells in sodium-free or chloride-free media inhibited the effects of PGE2. Measurements of the simultaneous fluxes of sodium and chloride showed that after PGE2 was added there was a net flux of chloride from the basal to the apical side (secretion) that was equal to the change in Isc. The effects of PGE2 were inhibited by furosemide in the basal medium. We conclude that PGE2 stimulates a process of chloride secretion in A6 cells.

Endothelin stimulates chloride secretion across canine tracheal epithelium

1991 ◽  
Vol 261 (2) ◽  
pp. L188-L194 ◽  
Author(s):  
P. I. Plews ◽  
Z. A. Abdel-Malek ◽  
C. A. Doupnik ◽  
G. D. Leikauf
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Second Messengers ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Tracheal Epithelium ◽  
Membrane Phospholipids ◽  
Cl Secretion ◽  
Tracheal Epithelial Cells ◽  
Tracheal Epithelial

The endothelins (ET) are a group of isopeptides produced by a number of cells, including canine tracheal epithelial cells. Because these compounds are endogenous peptides that may activate eicosanoid metabolism, we investigated the effects of ET on Cl secretion in canine tracheal epithelium. Endothelin 1 (ET-1) was found to produce a dose-dependent change in short-circuit current (Isc) that increased slowly and reached a maximal value within 10-15 min. When isopeptides of ET were compared, 300 nM ET-1 and ET-2 produced comparable maximal increases in Isc, whereas ET-3 produced smaller changes in Isc (half-maximal concentrations of 2.2, 7.2, and 10.4 nM, respectively). Ionic substitution of Cl with nontransported anions, iodide and gluconate, reduced ET-1-induced changes in Isc. Furthermore, the response was inhibited by the NaCl cotransport inhibitor, furosemide. In paired tissues, ET-1 significantly increased mucosal net 36Cl flux without significant effect on 22Na flux. The increase in Isc induced by ET was diminished by pretreatment with indomethacin. The second messengers mediating the increase in Isc were investigated in cultured canine tracheal epithelial cells. ET-1 stimulated the release of [3H]arachidonate from membrane phospholipids, increased intracellular Ca2+ (occasionally producing oscillations), and increased adenosine 3',5'-cyclic monophosphate accumulation. The latter was diminished by indomethacin. Thus ET is a potent agonist of Cl secretion (with the isopeptides having the following potency: ET-1 greater than or equal to ET-2 greater than ET-3) and acts, in part, through a cyclooxygenase-dependent mechanism.

Aspects of electrolyte transport across isolated dog retinal pigment epithelium

1986 ◽  
Vol 250 (5) ◽  
pp. F781-F784 ◽  
Author(s):  
S. Tsuboi ◽  
R. Manabe ◽  
S. Iizuka
Keyword(s):  
Retinal Pigment Epithelium ◽  
Apical Membrane ◽  
Short Circuit ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Apical Side ◽  
Net Flux ◽  
Net Fluxes

Transport of Na and Cl across the isolated dog retinal pigment epithelium (RPE) choroid was investigated. Under the short-circuit condition, a net Na flux was observed from choroid to retina and a net Cl flux was determined in the opposite direction. The current created by the net flux of these two ions was larger than the short-circuit current (SCC). Addition of 10(-5) M ouabain to the apical side inhibited net fluxes of both Na and Cl, whereas it reduced the SCC 84%. Addition of 10(-4) M furosemide to the apical side inhibited net Cl flux but had no effect on the net Na transport. The 10(-4) M furosemide reduced the SCC 38%. These drugs had no effect when applied to the basal side. Thus the transport of both Na and Cl depends on the Na-K-ATPase in the apical membrane of the dog RPE. A furosemide-sensitive neutral carrier at the apical membrane is suggested for the transport of Cl. Replacement of HCO3 with SO4 in the bathing solution caused an increase in the SCC, indicating the choroid-to-retina movement of HCO3 across the short-circuited dog RPE choroid.

Adenosine 3',5'-cyclic monophosphate stimulates chloride secretion in A6 epithelia

1986 ◽  
Vol 251 (5) ◽  
pp. C810-C814 ◽  
Author(s):  
M. Yanase ◽  
J. S. Handler
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Apical Surface ◽  
Cyclic Monophosphate ◽  
A6 Epithelia ◽  
In Series ◽  
Cl Channels ◽  
Solution Bathing ◽  
Stimulation Of

Basal and aldosterone-stimulated short-circuit current (Isc) of A6 epithelia are known to be equivalent to net apical to basal Na flux and are completely inhibited by 0.05 mM amiloride added to the solution bathing the apical surface of the epithelium. In the absence of amiloride, the Isc stimulated by adenosine 3',5'-cyclic monophosphate (cAMP) is also equivalent to net apical to basal Na flux. However, amiloride does not completely inhibit the cAMP-stimulated Isc. In this study, the cAMP-stimulated, amiloride-insensitive Isc was characterized, using vasopressin or forskolin to raise cell cAMP. After basal Isc is inhibited by amiloride, forskolin stimulates Isc, conductance, and bidirectional 36Cl flux. Stimulation of Isc depends on the presence of both Na and Cl; stimulation of conductance depends on the presence of Cl. 36Cl flux studies showed that the cAMP-stimulated, amiloride-insensitive Isc is equivalent to net Cl flux. It is inhibited by ouabain and by furosemide or bumetanide added to the solution bathing the basal surface of the epithelium. In view of the effect of cAMP in some other epithelia, we suggest that cAMP activates apical membrane Cl channels that are in series with a Na-K-Cl cotransporter in the basolateral plasma membrane.

scholarly journals AMP-activated protein kinase and adenosine are both metabolic modulators that regulate chloride secretion in the shark rectal gland (Squalus acanthias)

2018 ◽  
Vol 314 (4) ◽  
pp. C473-C482
Author(s):  
Rugina I. Neuman ◽  
Juliette A. M. van Kalmthout ◽  
Daniel J. Pfau ◽  
Dhariyat M. Menendez ◽  
Lawrence H. Young ◽  
...  
Keyword(s):  
Feedback Inhibition ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Squalus Acanthias ◽  
Catalytic Subunit ◽  
Rectal Gland ◽  
Apical Side ◽  
Shark Rectal Gland ◽  
Amp Activated Protein Kinase

The production of endogenous adenosine during secretagogue stimulation of CFTR leads to feedback inhibition limiting further chloride secretion in the rectal gland of the dogfish shark (Squalus acanthias). In the present study, we examined the role of AMP-kinase (AMPK) as an energy sensor also modulating chloride secretion through CFTR. We found that glands perfused with forskolin and isobutylmethylxanthine (F + I), potent stimulators of chloride secretion in this ancient model, caused significant phosphorylation of the catalytic subunit Thr172 of AMPK. These findings indicate that AMPK is activated during energy-requiring stimulated chloride secretion. In molecular studies, we confirmed that the activating Thr172 site is indeed present in the α-catalytic subunit of AMPK in this ancient gland, which reveals striking homology to AMPKα subunits sequenced in other vertebrates. When perfused rectal glands stimulated with F + I were subjected to severe hypoxic stress or perfused with pharmacologic inhibitors of metabolism (FCCP or oligomycin), phosphorylation of AMPK Thr172 was further increased and chloride secretion was dramatically diminished. The pharmacologic activation of AMPK with AICAR-inhibited chloride secretion, as measured by short-circuit current, when applied to the apical side of shark rectal gland monolayers in primary culture. These results indicate that that activated AMPK, similar to adenosine, transmits an inhibitory signal from metabolism, that limits chloride secretion in the shark rectal gland.

scholarly journals Characterization of PKA isoforms and kinase-dependent activation of chloride secretion in T84 cells

1998 ◽  
Vol 275 (2) ◽  
pp. C562-C570 ◽  
Author(s):  
A. K. Singh ◽  
K. Taskén ◽  
W. Walker ◽  
R. A. Frizzell ◽  
S. C. Watkins ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Immunogold Electron Microscopy ◽  
Apical Plasma Membrane ◽  
Epithelial Cell Line ◽  
Type I ◽  
Type Ii ◽  
T84 Cells

Chloride exit across the apical membranes of secretory epithelial cells is acutely regulated by the cAMP-mediated second messenger cascade. To better understand the regulation of transepithelial chloride secretion, we have characterized the complement of cAMP-dependent protein kinase (PKA) isoforms present in the human colonic epithelial cell line T84. Our results show that both type I and type II PKA are present in T84 cells. Immunoprecipitation of 8-azido-[32P]cAMP-labeled cell lysates revealed that the major regulatory subunits of PKA were RIα and RIIα. In addition, immunogold electron microscopy showed that RIIα labeling was found on membranes of the trans Golgi network and on apical plasma membrane. In contrast, RIα was randomly distributed throughout the cytoplasm, with no discernible membrane association. Northern blot analysis of T84 RNA revealed that Cα was the predominantly expressed catalytic subunit. Short-circuit current measurements were performed in the presence of combinations of site-selective cAMP analog pairs to preferentially activate either PKA type I or PKA type II in intact T84 cell monolayers. Maximal levels of chloride secretion (∼100 μA/cm2) were observed for both type I and type II PKA-selective analog pairs. Subsequent addition of forskolin was unable to further increase chloride secretion. Thus activation of either type I or type II PKA is able to maximally stimulate chloride secretion in T84 colonic epithelial cells.

K+ transport and capacitance of the basolateral membrane of the larval frog skin

1997 ◽  
Vol 273 (6) ◽  
pp. C1995-C2001 ◽  
Author(s):  
Stanley D. Hillyard ◽  
Horacio F. Cantiello ◽  
Willy Van Driessche
Keyword(s):  
Epithelial Cells ◽  
Voltage Clamp ◽  
Time Course ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Skin Resistance ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Low Noise ◽  
Apical Surface

Skin from larval bullfrogs was mounted in an Ussing-type chamber in which the apical surface was bathed with a Ringer solution containing 115 mM K+ and the basolateral surface was bathed with a Ringer solution containing 115 mM Na+. Ion transport was measured as the short-circuit current ( I sc) with a low-noise voltage clamp, and skin resistance ( R m) was measured by applying a direct current voltage pulse. Membrane impedance was calculated by applying a voltage signal consisting of 53 sine waves to the command stage of the voltage clamp. From the ratio of the Fourier-transformed voltage and current signals, it was possible to calculate the resistance and capacitance of the apical and basolateral membranes of the epithelium ( R a and R b, C a and C b, respectively). With [Formula: see text] as the anion, R m decreased rapidly within 5 min following the addition of 150 U/ml nystatin to the apical solution, whereas I sc increased from 0.66 to 52.03 μA/cm2 over a 60-min period. These results indicate that nystatin becomes rapidly incorporated into the apical membrane and that the increase in basolateral K+ permeability requires a more prolonged time course. Intermediate levels of I sc were obtained by adding 50, 100, and 150 U/ml nystatin to the apical solution. This produced a progressive decrease in R a and R b while C a and C b remained constant. With Cl− as the anion, I sc values increased from 2.03 to 89.57 μA/cm2 following treatment with 150 U/ml nystatin, whereas with gluconate as the anion I sc was only increased from 0.63 to 11.64 μA/cm2. This suggests that the increase in basolateral K+permeability produced by nystatin treatment, in the presence of more permeable anions, is due to swelling of the epithelial cells of the tissue rather than the gradient for apical K+ entry. Finally, C b was not different among skins exposed to Cl−,[Formula: see text], or gluconate, despite the large differences in I sc, nor did inhibition of I scby treatment with hyperosmotic dextrose cause significant changes in C b. These results support the hypothesis that increases in cell volume activate K+ channels that are already present in the basolateral membrane of epithelial cells.

Phospholipase C controls chloride-dependent short-circuit current in human bronchial epithelial cells

2020 ◽  
Author(s):  
Chloé Grebert ◽  
Frederic Becq ◽  
Clarisse Vandebrouck
Keyword(s):  
Epithelial Cells ◽  
Phospholipase C ◽  
Chloride Channels ◽  
Short Circuit ◽  
Ion Homeostasis ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Bronchial Epithelial Cells ◽  
Airway Epithelial ◽  
Bronchial Epithelial

Chloride secretion by airway epithelial cells is primordial for water and ion homeostasis and airways surface prevention of infections. This secretion is impaired in several human diseases, including cystic fibrosis, a genetic pathology due to CFTR gene mutations leading to chloride channel defects. A potential therapeutic approach is aiming at increasing chloride secretion either by correcting the mutated CFTR itself or by stimulating non-CFTR chloride channels at the plasma membrane. Here we studied the role of phospholipase C in regulating the transepithelial chloride secretion in human airway epithelial 16HBE14o- and CFBE cells over expressing WT‑ or F508del‑CFTR. Western blot analysis shows expression of the three endogenous PLC isoforms PLCd1, PLCg1 and PLCb3 in 16HBE14o‑ cells. In 16HBE14o‑ cells we performed Ussing chamber experiments after silencing each of these PLC isoforms or using the PLC inhibitor U73122 or its inactive analogue U73343. Our results show the involvement of PLCb3 and PLCg1 in CFTR-dependent short-circuit current activated by forskolin, but not PLCd1. In CFBE-WT CFTR and corrected CFBE‑F508del CFTR cells, PLCb3 silencing also inhibits CFTR‑dependent current activated by forskolin and UTP-activated calcium-dependent chloride channels (CaCC). Our study supports the importance of PLC in maintaining CFTR‑dependent chloride secretion over time, getting maximal CFTR-dependent current and increasing CaCC activation in bronchial epithelial cells.

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.

Atriopeptin stimulates chloride secretion in cultured shark rectal gland cells

1991 ◽  
Vol 260 (5) ◽  
pp. C1125-C1130 ◽  
Author(s):  
K. J. Karnaky ◽  
J. D. Valentich ◽  
M. G. Currie ◽  
W. F. Oehlenschlager ◽  
M. P. Kennedy
Keyword(s):  
Epithelial Cells ◽  
Plasma Membranes ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Rectal Gland ◽  
Cl Secretion ◽  
Intracellular Cgmp ◽  
Similar Dose ◽  
Shark Rectal Gland

Monolayer cultures of shark rectal gland (SRG) epithelial cells were treated with atriopeptin (AP), and the effects on Cl- secretion and intracellular guanosine 3',5'-cyclic monophosphate (cGMP) accumulation were examined. Basolateral or apical exposure to 10(-7) M AP markedly stimulated (8-fold) Cl(-)-dependent, bumetanide-sensitive, short-circuit current (Isc). The AP-stimulated Isc exhibited transient oscillations before reaching a steady state. This behavior is not observed when Isc is activated by other secretagogues such as vasoactive intestinal peptide, 2-chloroadenosine, forskolin, or ionomycin. Intracellular cGMP was concomitantly elevated (10-fold) by 10(-7) M AP. Both Isc stimulation and cGMP accumulation responses exhibited a similar dose dependency beginning at an AP concentration of 1 nM. The bilateral response to AP suggests the presence of receptors on both apical and basolateral plasma membranes. These results are the first demonstration of a direct effect of AP on Cl(-)-secreting epithelial cells. These data also suggest a role for cGMP in mediating Cl- secretion in these cells.

Effect of angiotensins on electrogenic anion transport in monolayer cultures of rat epididymis

1990 ◽  
Vol 125 (3) ◽  
pp. 449-456 ◽  
Author(s):  
P. Y. D. Wong ◽  
W. O. Fu ◽  
S. J. Huang ◽  
W. K. Law
Keyword(s):  
Fluid Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Angiotensin Receptors ◽  
Apical Surface ◽  
Monolayer Cultures ◽  
Rat Epididymis ◽  
Specific Antagonist ◽  
Cauda Epididymidis

ABSTRACT Confluent monolayers cultured from the rat cauda epididymidis have been shown to respond to angiotensin I (AI) and angiotensin II (AII) when studied under short-circuit conditions and bathed on both sides with Krebs–Henseleit solution. Both the decapeptide AI and the octapeptide AII elicited transient increases in short-circuit current (SCC) when added to the basolateral as well as to the apical surfaces, with the effect of basolateral application greater than that of apical application. The maximal responses produced by AI and AII were similar with median effective concentrations of 20 to 80 nmol/l. The increase in SCC by AII was dependent upon extracellular Cl− and was inhibited by addition of a Cl− channel blocker, diphenylamine 2-carboxylate, to the apical surface. These patterns of activity suggest that the SCC responses to angiotensins result from electrogenic chloride secretion. Pretreating the monolayers with captopril (100 nmol/l), an angiotensin-converting enzyme (ACE) inhibitor, reduced the response to basolateral application of AI, but completely abolished the response to AI added apically. These results suggest that the response to apical addition of AI was due to conversion of AI to AII which interacts with apical angiotensin receptors. This conversion was mediated by ACE which has been detected in epididymal monolayers. Of the endogenous ACE activity, 86% was found to be inhibited by captopril (100 nmol/l). Responses of the epididymal monolayers to angiotensins were mediated by specific angiotensin receptors. [Sar1,Ile8]-AII, a specific antagonist of the AII receptor, completely inhibited the responses to AI and All but had no effect on the responses to bradykinin and endothelin. The effects of All were mediated by eicosanoid formation since piroxicam, a cyclooxygenase inhibitor, inhibited the AII-induced increase in SCC. This is the first study to demonstrate an effect of angiotensin on epididymal functions. We propose that angiotensin formed locally in the epididymis may play a role in the regulation of electrolyte and fluid transport. Journal of Endocrinology (1990) 125, 449–456

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