Regulation of acid secretion and paracellular permeability by F-actin in the bullfrog,Rana catesbeiana

2002 ◽  
Vol 282 (3) ◽  
pp. G519-G526 ◽  
Author(s):  
Tarik A. Abdul-Ghaffar Al-Shaibani ◽  
Susan J. Hagen
Keyword(s):  
Acid Secretion ◽  
Actin Filaments ◽  
Rana Catesbeiana ◽  
Paracellular Permeability ◽  
Bicarbonate Transport ◽  
Back Diffusion ◽  
Mucosal Permeability ◽  
Ussing Chambers ◽  
Junction Structure ◽  
Mannitol Flux

G526, 2002. First published December 5, 2001; 10.1152/ajpgi.00393. 2001.—Many studies have implicated F-actin in the regulation of gastric acid secretion using cytochalasin D (CD) to disrupt apical actin filaments in oxyntic cells. However, it is known that CD also affects mucosal permeability by disrupting tight junction structure. Here we investigated the contribution of F-actin to mucosal permeability and acid secretion in the stomach using CD. Stomachs were mounted in Ussing chambers and acid secretion (stimulated or inhibited), transepithelial resistance (TER), mannitol flux, bicarbonate transport, and dual mannitol/sodium fluxes were determined with or without CD. H+back diffusion was predicted from its diffusion coefficient. Incubation with CD resulted in a significant reduction in stimulated acid secretion. TER was unchanged in stimulated tissues but significantly reduced in inhibited tissues. Mannitol flux, bicarbonate transport, and H+-back diffusion increased significantly with CD. However, the rates of bicarbonate and H+flux were not large enough to account for the inhibition of acid secretion. These findings demonstrate that actin filaments regulate paracellular permeability and play an essential role in the regulation of acid secretion in the stomach.

Restitution of the bullfrog gastric mucosa is dependent on a DIDS-inhibitable pathway not related to \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{HCO}_{3}^{-}\) \end{document} ion transport

2004 ◽  
Vol 286 (4) ◽  
pp. G596-G605 ◽  
Author(s):  
Susan J. Hagen ◽  
Sarah W. Morrison ◽  
Christina S. Law ◽  
David X. Yang
Keyword(s):  
Cell Migration ◽  
Gastric Mucosa ◽  
Basement Membrane ◽  
Ion Transport ◽  
Rana Catesbeiana ◽  
Transepithelial Resistance ◽  
Ussing Chambers ◽  
Ion Substitution ◽  
Transport Inhibitors ◽  
Mannitol Flux

This study was conducted to determine the contribution of ion transport to restitution after injury in the gastric mucosa. For this, intact sheets of stomach from the bullfrog, Rana catesbeiana, were mounted in Ussing chambers. Restitution was evaluated in the presence or absence of ion transport inhibitors amiloride, DIDS, and bumetanide to block Na+/H+ exchange, [Formula: see text]/[Formula: see text] exchange and [Formula: see text]/[Formula: see text] co-transport, and Na+-K+-2Cl- cotransport, respectively. Ion substitution experiments with Na+-free, Cl--free, and [Formula: see text]-free solutions were also performed. Injury to the mucosa was produced with 1 M NaCl, and restitution was evaluated by recovery of transepithelial resistance (TER), mannitol flux, and morphology. Amiloride, bumetanide, Cl--free, or [Formula: see text]-free solutions did not affect restitution. In Na+-free solutions, recovery of TER and mannitol flux did not occur because surface cells did not attach to the underlying basement membrane. In contrast, all aspects of restitution were inhibited by DIDS, a compound that inhibits Na+-dependent [Formula: see text] transport. Because [Formula: see text]-free solutions did not inhibit restitution, it was concluded that DIDS must block a yet undefined pathway not involved in [Formula: see text] ion transport but essential for cell migration after injury and restitution in the gastric mucosa.

scholarly journals The Leak Pathway: A Pathway in Flux

2019 ◽  
Author(s):  
Ashley Monaco ◽  
Ben Ovryn ◽  
Josephine Axis ◽  
Kurt Amsler
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Tight Junction ◽  
Molecular Mechanism ◽  
Actin Filaments ◽  
Molecular Basis ◽  
Paracellular Permeability ◽  
Permeability Barrier ◽  
Junction Structure ◽  
Leak Pathway

The epithelial cell tight junction structure is the site of the transepithelial movement of solutes and water between epithelial cells (paracellular permeability). Paracellular permeability can be divided into two distinct pathways, the Pore Pathway mediating the movement of small ions and solutes and the Leak Pathway mediating the movement of large solutes. Claudin proteins form the basic paracellular permeability barrier and mediate the movement of small ions and solutes via the Pore Pathway. The Leak Pathway remains less understood. Several proteins have been implicated in mediating the Leak Pathway, including occludin, ZO proteins, tricellulin, and actin filaments, but the proteins comprising the Leak Pathway remain unresolved. The properties of the Leak Pathway, such as its molecular mechanism, its regulation, and whether or not it has a potential size limit, remain controversial. This review will trace the evolution of the Leak Pathway concept from its origins, will discuss the current information about the properties of the Leak Pathway, and will discuss recent research suggesting a possible molecular basis for the Leak Pathway. Based on these findings, we propose a model for the molecular mechanism underlying the Leak Pathway and its regulation.

Physiological concentrations of bile salts inhibit recovery of ischemic-injured porcine ileum

2004 ◽  
Vol 287 (2) ◽  
pp. G399-G407 ◽  
Author(s):  
Nigel B. Campbell ◽  
Craig G. Ruaux ◽  
Donnie E. Shifflett ◽  
Jöerg M. Steiner ◽  
David A. Williams ◽  
...  
Keyword(s):  
Barrier Function ◽  
Bile Salts ◽  
Deoxycholic Acid ◽  
Paracellular Permeability ◽  
Mucosal Barrier ◽  
Histological Evaluation ◽  
Ileal Mucosa ◽  
Ussing Chambers ◽  
Mucosal Barrier Function ◽  
Mannitol Flux

We have previously shown rapid in vitro recovery of barrier function in porcine ischemic-injured ileal mucosa, attributable principally to reductions in paracellular permeability. However, these experiments did not take into account the effects of luminal contents, such as bile salts. Therefore, the objective of this study was to evaluate the role of physiological concentrations of deoxycholic acid in recovery of mucosal barrier function. Porcine ileum was subjected to 45 min of ischemia, after which mucosa was mounted in Ussing chambers and exposed to varying concentrations of deoxycholic acid. The ischemic episode resulted in significant reductions in transepithelial electrical resistance (TER), which recovered to control levels of TER within 120 min, associated with significant reductions in mucosal-to-serosal 3H-labeled mannitol flux. However, treatment of ischemic-injured tissues with 10−5 M deoxycholic acid significantly inhibited recovery of TER with significant increases in mucosal-to-serosal 3H-labeled mannitol flux, whereas 10−6 M deoxycholic acid had no effect. Histological evaluation at 120 min revealed complete restitution regardless of treatment, indicating that the breakdown in barrier function was due to changes in paracellular permeability. Similar effects were noted with the application of 10−5 M taurodeoxycholic acid, and the effects of deoxycholic acid were reversed with application of the Ca2+-mobilizing agent thapsigargin. Deoxycholic acid at physiological concentrations significantly impairs recovery of epithelial barrier function by an effect on paracellular pathways, and these effects appear to be Ca2+ dependent.

scholarly journals The Epithelial Cell Leak Pathway

2021 ◽  
Vol 22 (14) ◽  
pp. 7677
Author(s):  
Ashley Monaco ◽  
Ben Ovryn ◽  
Josephine Axis ◽  
Kurt Amsler
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Tight Junction ◽  
Actin Filaments ◽  
Molecular Basis ◽  
Paracellular Permeability ◽  
Historical Background ◽  
Permeability Barrier ◽  
Junction Structure ◽  
Leak Pathway

The epithelial cell tight junction structure is the site of the transepithelial movement of solutes and water between epithelial cells (paracellular permeability). Paracellular permeability can be divided into two distinct pathways, the Pore Pathway mediating the movement of small ions and solutes and the Leak Pathway mediating the movement of large solutes. Claudin proteins form the basic paracellular permeability barrier and mediate the movement of small ions and solutes via the Pore Pathway. The Leak Pathway remains less understood. Several proteins have been implicated in mediating the Leak Pathway, including occludin, ZO proteins, tricellulin, and actin filaments, but the proteins comprising the Leak Pathway remain unresolved. Many aspects of the Leak Pathway, such as its molecular mechanism, its properties, and its regulation, remain controversial. In this review, we provide a historical background to the evolution of the Leak Pathway concept from the initial examinations of paracellular permeability. We then discuss current information about the properties of the Leak Pathway and present current theories for the Leak Pathway. Finally, we discuss some recent research suggesting a possible molecular basis for the Leak Pathway.

Apical acidification induces paracellular injury in canine gastric mucosal monolayers

1994 ◽  
Vol 267 (6) ◽  
pp. G1012-G1020 ◽  
Author(s):  
M. C. Chen ◽  
A. Chang ◽  
T. Buhl ◽  
M. Tanner ◽  
A. H. Soll
Keyword(s):  
Short Circuit ◽  
Phase 1 ◽  
Short Circuit Current ◽  
Paracellular Permeability ◽  
Ussing Chambers ◽  
Low Concentrations ◽  
Three Phase ◽  
Mucosal Cells ◽  
Primary Monolayer ◽  
Primary Monolayer Cultures

We used primary monolayer cultures of enzyme-dispersed canine oxyntic mucosal cells mounted in Ussing chambers to characterize the apical barrier to H+. [3H]mannitol flux (MF) and [14C]inulin flux (IF) were used as size probes for tight junctions. Apical H+ produced a three-phase effect. In phase 1, as the apical pH was decreased from 7 to about 2.5, resistance (R) increased, but short-circuit current (Isc) did not change. In phase 2, an increased paracellular permeability developed at pH below 2.5-1.7, evidenced by decreased R and increased MF but not IF. Size sieving and monolayer integrity were preserved, and this paracellular leak was either fully reversed or stabilized by apical neutralization, depending on the duration of the paracellular leak. In phase 3, after sustained exposure to an apical pH below approximately 2, transepithelial integrity was lost; R decreased to fluid R, and both MF and IF increased. Basolateral acidification below pH 5.5 produced rapid monolayer disruption. Low concentrations of cytochalasin D (CD) decreased R and increased MF but not IF; apical acidification to pH 4 after CD increased R and decreased the MF, indicating reduced paracellular permeability by apical H+. Apical amiloride did not alter Isc; however, after 48 h of treatment with hydrocortisone and insulin, an amiloride-sensitive Isc component became evident. Our data indicate that the increase in R observed with apical acidification reflects decreased paracellular permeability and that the earliest injury with apical acidification is a selective paracellular leak.

Acid secretion in isolated guinea pig colon

1987 ◽  
Vol 253 (2) ◽  
pp. G155-G164 ◽  
Author(s):  
Y. Suzuki ◽  
K. Kaneko
Keyword(s):  
Carbonic Anhydrase ◽  
Guinea Pig ◽  
Acid Secretion ◽  
Proximal Part ◽  
Bathing Solution ◽  
Maximal Effect ◽  
Dose Dependency ◽  
Ussing Chambers ◽  
Mucosal Acidification ◽  
Ph Stat

Isolated guinea pig distal colons secreted acid into the mucosal bathing solution at a rate of 1.0-1.5 mumol X cm-2 X h-1 when the preparations were mounted in Ussing chambers and bathed with HCO3(-)-CO2-free solution. The rates of the acidification and alkalinization of the solutions were measured by a pH stat system or calculated from changes in the pH of the solution. The acid secretion was localized in the middle and distal parts of the colon but absent in the proximal part of the colon and the cecum. The mucosal acidification was accompanied by serosal alkalinization, the rate of the latter being approximately 60% of the former. A carbonic anhydrase inhibitor, methazolamide (10(-4) M), reduced both the mucosal acidification and serosal alkalinization rates by a similar magnitude. The mucosal acidification was completely abolished by mucosal K+-free conditions but unaffected by mucosal Na+-free conditions. Ouabain added to the mucosal solution promptly inhibited the acid secretion. Dose dependency of the inhibition conformed to the Michaelis-Menten equation with a half-maximal effect at 4 X 10(-6) M. When the pH of the mucosal solution was reduced to 4.3, the rate of the mucosal acidification remained essentially the same as that at pH = 7.4. Vanadate (10(-4) M) added to both the mucosal and serosal solutions significantly reduced the mucosal acidification rate. These results suggest that CO2 derived from the epithelial metabolism is hydrated by carbonic anhydrase in the cell and released H+ enters the mucosal solution while HCO3- enters the serosal solution. H+ exit across the mucosal membrane may be mediated by H+-ATPase that is sensitive to ouabain.

Apical EGF receptors regulate epithelial barrier to gastric acid: endogenous TGF-α is an essential facilitator

2002 ◽  
Vol 283 (5) ◽  
pp. G1098-G1106 ◽  
Author(s):  
Monica C. Chen ◽  
Travis E. Solomon ◽  
Robert Kui ◽  
Andrew H. Soll
Keyword(s):  
Transforming Growth Factor ◽  
Paracellular Permeability ◽  
Transepithelial Electrical Resistance ◽  
Egf Receptors ◽  
Apparent Effect ◽  
Endogenous Ligand ◽  
Ussing Chambers ◽  
Egfr Ligand ◽  
Egf Family ◽  
Primary Canine

In previous studies, we found that apical and basolateral EGF receptors (EGFR) on primary canine gastric monolayers decreased paracellular permeability, evident by increased transepithelial electrical resistance (TER) and decreased flux of [3H]mannitol (MF). After studying monolayers in Ussing chambers, we now report that treatment with apical, but not basolateral, EGF enhanced tolerance to apical H+, evident by a slower decay in TER and an attenuated rise in MF. Enhanced tolerance to apical acid was evident within 10 min of treatment with apical EGF. Immunoneutralization of endogenous transforming growth factor (TGF)-α accelerated the drop in TER and the rise in MF in response to apical acidification; apical EGF reversed these effects. Study of monolayers cultured in Transwell inserts showed that immunoblockade of basolateral, but not apical, EGFR also impaired the resistance to apical acidification and enhanced MF. We conclude that apical EGFR regulates the barrier to apical acidification via effects on paracellular resistance. Although exogenous basolateral EGF has a less apparent effect on the barrier to acid, endogenous ligand active at basolateral EGFR plays an important role in maintaining the barrier to apical acid. Our data implicate a role for an apical EGFR ligand, which may be EGF or another member of the EGF family.

Melatonin inhibits alcohol-induced increases in duodenal mucosal permeability in rats in vivo

2013 ◽  
Vol 305 (1) ◽  
pp. G95-G105 ◽  
Author(s):  
Anna Sommansson ◽  
Wan Salman Wan Saudi ◽  
Olof Nylander ◽  
Markus Sjöblom
Keyword(s):  
Nicotinic Receptor ◽  
Mucosal Injury ◽  
Paracellular Permeability ◽  
Ethanol Exposure ◽  
Mucosal Permeability ◽  
Duodenal Motility ◽  
Gastrointestinal Barrier ◽  
Induced Changes ◽  
Epithelial Inflammation

Increased intestinal permeability is often associated with epithelial inflammation, leaky gut, or other pathological conditions in the gastrointestinal tract. We recently found that melatonin decreases basal duodenal mucosal permeability, suggesting a mucosal protective mode of action of this agent. The aim of the present study was to elucidate the effects of melatonin on ethanol-, wine-, and HCl-induced changes of duodenal mucosal paracellular permeability and motility. Rats were anesthetized with thiobarbiturate and a ∼30-mm segment of the proximal duodenum was perfused in situ. Effects on duodenal mucosal paracellular permeability, assessed by measuring the blood-to-lumen clearance of 51Cr-EDTA, motility, and morphology, were investigated. Perfusing the duodenal segment with ethanol (10 or 15% alcohol by volume), red wine, or HCl (25–100 mM) induced concentration-dependent increases in paracellular permeability. Luminal ethanol and wine increased, whereas HCl transiently decreased duodenal motility. Administration of melatonin significantly reduced ethanol- and wine-induced increases in permeability by a mechanism abolished by the nicotinic receptor antagonists hexamethonium (iv) or mecamylamine (luminally). Signs of mucosal injury (edema and beginning of desquamation of the epithelium) in response to ethanol exposure were seen only in a few villi, an effect that was histologically not changed by melatonin. Melatonin did not affect HCl-induced increases in mucosal permeability or decreases in motility. Our results show that melatonin reduces ethanol- and wine-induced increases in duodenal paracellular permeability partly via an enteric inhibitory nicotinic-receptor dependent neural pathway. In addition, melatonin inhibits ethanol-induced increases in duodenal motor activity. These results suggest that melatonin may serve important gastrointestinal barrier functions.

Uremia increases gastric mucosal permeability and acid back-diffusion injury in the rat

1992 ◽  
Vol 103 (6) ◽  
pp. 1762-1768 ◽  
Author(s):  
Enrique Quintero ◽  
Jonathan Kaunitz ◽  
Yasuhiro Nishizaki ◽  
Roberto De Giorgio ◽  
Catia Sternini ◽  
...  
Keyword(s):  
Back Diffusion ◽  
Mucosal Permeability
Sign in / Sign up

Export Citation Format

Share Document