Source and distribution of factors in locust nervous system which stimulate rectal Cl− transport

1985 ◽  
Vol 63 (1) ◽  
pp. 37-41 ◽  
Author(s):  
J. Proux ◽  
B. Proux ◽  
J. Phillips
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Active Form ◽  
Short Circuit Current ◽  
Neurosecretory Cells ◽  
Neuroendocrine Cells ◽  
Response Curves ◽  
Ussing Chambers ◽  
Cl Transport ◽  
Low Concentrations

Corpus cardiacum (CC) of locusts contains a potent stimulant of rectal Cl transport, i.e., chloride transport stimulating hormone (CTSH). Extracts of other locust tissues which contain neuroendocrine cells were assayed for their ability to stimulate Cl-dependent, short-circuit current (Isc) across recta mounted in Ussing chambers. Dose–response curves indicated that only brain (particularly the pars intercerebralis, PI) contained substantial stimulatory activity, but this was still at very low concentrations compared with CTSH activity in CC. Destruction of either the PI or the nerve tract from PI to CC (i.e., NCC I) reduced CTSH levels in the CC. In contrast, destruction of lateral neurosecretory cells (NSCs) of the brain had no effect. The results suggest that CTSH is synthesized in NSCs of the PI and is transported down NCC I to the CC where it may mature to a more active form.

Interaction between sodium and chloride transport in canine tracheal mucosa

1979 ◽  
Vol 46 (1) ◽  
pp. 111-119 ◽  
Author(s):  
F. J. Al-Bazzaz ◽  
Q. Al-Awqati
Keyword(s):  
Hormonal Regulation ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Na Transport ◽  
Tracheal Mucosa ◽  
Electrically Conductive ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Cl Transport

Canine tracheal mucosae were dissected and mounted as flat sheets in Ussing chambers. Unidirectional isotope fluxes of 22Na and 36Cl were performed across paired mucosae from the same animal. The average spontaneous potential difference was 42 + 1.2 mV (mean +/- SE) lumen negative. The short-circuit current (SCC) 3.09 +/- 0.36 mueq/cm2.h was accounted for by a net Cl secretion of 2.46 +/- 0.26 mueq/cm2.h toward the mucosa and net Na absorption of 0.46 +/- 0.13 mueq/cm2.h toward submucosa. Removal of Cl depressed SCC but had no effect on unidirectional or net Na transport (n = 7). By contrast, removal of Na (n = 6) or the addition of ouabain (n = 7) abolished net Cl secretion and greatly reduced SCC. Theophylline (n = 6) added to the submucosal bath no significant effect on Na transport but stimulated SCC and Cl secretion, suggesting hormonal regulation of Cl transport. The results suggest that the active transport of Na and Cl in this epithelium occur by electrically conductive pathways, i.e., the transport is “electrogenic.” Further it appears that Na transport is independent of the presence of Cl but that Cl transport depends on some parameter of active Na transport.

Na and Cl Transport across the Isolated Anterior Intestine of the Plaice Pleuronectes Platessa

1981 ◽  
Vol 90 (1) ◽  
pp. 123-142
Author(s):  
M. M. P. RAMOS ◽  
J. C. ELLORY
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Negative Potential ◽  
Loop Diuretics ◽  
Significant Part ◽  
Cl Transport ◽  
Anterior Intestine ◽  
Short Circuit Currents ◽  
Na Uptake

1. The tissue was found to have a serosa negative potential, and short-circuit currents equivalent to the net Cl transport. 2. A significant part of the Cl uptake was Na dependent and a similar fraction of the Na uptake was Cl dependent. 3. Short-circuit current and uptake of both ions were inhibited by loop diuretics and analogues. 4. I80 and P.D. were abolished by ouabain. 5. The observations are consistent with the idea of a coupled NaCl entry into the cell, using the energy inherent in the Na gradient; Na being pumped out of the cells by the Na pump and followed electrically by Cl−. Net chloride transport and the serosa negative potential would be a consequence of the permselective properties of the junctions allowing Na but not Cl to recycle back to the mucosal solution.

Mechanisms of sodium and chloride transport across equine tracheal epithelium

1990 ◽  
Vol 259 (6) ◽  
pp. L459-L467 ◽  
Author(s):  
G. J. Tessier ◽  
T. R. Traynor ◽  
M. S. Kannan ◽  
S. M. O3'Grady
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Tracheal Epithelium ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Cotransport System ◽  
Ethanesulfonic Acid

Equine tracheal epithelium, stripped of serosal muscle, mounted in Ussing chambers, and bathed in plasmalike Ringer solution generates a serosa-positive transepithelial potential of 10–22 mV and a short-circuit current (Isc) of 70–200 microA/cm2. Mucosal amiloride (10 microM) causes a 40–60% decrease in Isc and inhibits the net transepithelial Na flux by 95%. Substitution of Cl with gluconate resulted in a 30% decrease in basal Isc. Bicarbonate substitution with 20 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid decreased the Isc by 21%. The Cl-dependent Isc was inhibited by serosal addition of 1 mM amiloride. Bicarbonate replacement or serosal amiloride (1 mM) inhibits the net Cl flux by 72 and 69%, respectively. Bicarbonate replacement significantly reduces the effects of serosal amiloride (1 mM) on Isc, indicating its effect is HCO3 dependent. Addition of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP; 100 microM) causes a 40% increase in Isc. This effect is inhibited by subsequent addition of 10 microM serosal bumetanide. Bumetanide (10 microM) reduces net Cl secretion following stimulation with 8-BrcAMP (100 microM). Serosal addition of BaCl2 (1 mM) causes a reduction in Isc equal to that following Cl replacement in the presence or absence of 100 microM cAMP. These results suggest that 1) Na absorption depends on amiloride-inhibitable Na channels in the apical membrane, 2) Cl influx across the basolateral membrane occurs by both a Na-H/Cl-HCO3 parallel exchange mechanism under basal conditions and by a bumetanide-sensitive Na-(K?)-Cl cotransport system under cAMP-stimulated conditions, and 3) basal and cAMP-stimulated Cl secretion depends on Ba-sensitive K channels in the basolateral membrane.

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.

Expression of the chloride channel ClC-2 in the murine small intestine epithelium

2000 ◽  
Vol 279 (6) ◽  
pp. C1787-C1794 ◽  
Author(s):  
Katalin Gyömörey ◽  
Herman Yeger ◽  
Cameron Ackerley ◽  
Elizabeth Garami ◽  
Christine E. Bear
Keyword(s):  
Small Intestine ◽  
Chloride Channel ◽  
Chloride Transport ◽  
Short Circuit ◽  
Chloride Ion ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Ussing Chambers ◽  
Dependent Change ◽  
Knockout Animals

The chloride channel ClC-2 has been implicated in neonatal airway chloride secretion. To assess its role in secretion by the small intestine, we assessed its subcellular expression in ileal segments obtained from mice and studied the chloride transport properties of this tissue. Chloride secretion across the mucosa of murine ileal segments was assessed in Ussing chambers as negative short-circuit current ( Isc). If ClC-2 contributed to chloride secretion, we predicted on the basis of previous studies that negative Iscwould be stimulated by dilution of the mucosal bath and that this response would depend on chloride ion and would be blocked by the chloride channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid but not by DIDS. In fact, mucosal hypotonicity did stimulate a chloride-dependent change in Iscthat exhibited pharmacological properties consistent with those of ClC-2. This secretory response is unlikely to be mediated by the cystic fibrosis transmembrane conductance regulator (CFTR) channel because it was also observed in CFTR knockout animals. Assessment of the native expression pattern of ClC-2 protein in the murine intestinal epithelium by confocal and electron microscopy showed that ClC-2 exhibits a novel distribution, a distribution pattern somewhat unexpected for a channel involved in chloride secretion. Immunolabeled ClC-2 was detected predominantly at the tight junction complex between adjacent intestinal epithelial cells.

Sodium and chloride transport across the isolated porcine gallbladder

1989 ◽  
Vol 257 (1) ◽  
pp. C45-C51 ◽  
Author(s):  
S. M. O'Grady ◽  
P. J. Wolters
Keyword(s):  
Apical Membrane ◽  
Chloride Transport ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Disulfonic Acid ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Conductive Pathway

Porcine gallbladder, stripped of serosal muscle, mounted in Ussing chambers, and bathed in plasma-like Ringer solution generates a serosal positive transepithelial potential of 4-7 mV and a short-circuit current (Isc) of 50-120 microA/cm2. Substitution of Cl with gluconate or HCO3 with N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) results in a 50% decrease in Isc. Treatment with 1 mM amiloride (mucosal side) or 0.1 mM acetazolamide (both sides) causes 25-27% inhibition of the Isc. Mucosal addition of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid inhibits the Isc by 17%. Serosal addition of 0.1 mM bumetanide inhibits the Isc by 28%. Amiloride (1 mM) inhibits the net transepithelial fluxes of Na and Cl by 55 and 41%, respectively. Substitution of Cl with gluconate inhibits the net Na flux by 50%, whereas substitution of HCO3 with HEPES inhibits 85-90% of the net Na flux and changes Cl absorption to net secretion. Based on these results, it is hypothesized that Na and Cl transport across the apical membrane is mediated by two pathways, Na-H/Cl-HCO3 exchange and Na-HCO3 cotransport. Partial recycling of Cl and HCO3 presumably occurs through a Cl conductive pathway and Cl-HCO3 exchange, respectively, in the apical membrane. This results in net Na absorption, which accounts for most of the Isc observed under basal conditions. The effect of bumetanide on the basolateral membrane and the fact that Cl secretion occurs when HCO3 is absent suggests that Cl secretion involves a basolateral NaCl or Na-K-Cl cotransport system arranged in series with a Cl conductive pathway in the apical membrane.

Regional adrenergic regulation of ion transport across the isolated porcine gallbladder

1993 ◽  
Vol 264 (4) ◽  
pp. R703-R707 ◽  
Author(s):  
M. D. Duvall ◽  
S. M. O'Grady
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Gallbladder Epithelium ◽  
Adrenergic Agonist ◽  
Ussing Chambers ◽  
Cl Transport ◽  
Beta Agonists ◽  
Beta 2

The regional transport properties of the porcine gallbladder epithelium were studied using Ussing chambers in which tissues were bathed in porcine Ringer solution. Under basal conditions, tissues from the neck absorbed Na and Cl. Fundic tissues also absorbed Na, but net Cl transport was not different from zero. Serosal norepinephrine (NE; 0.1 microM) stimulated Na and Cl absorption in the neck but only Cl absorption in the fundus. The effects of NE on Na and Cl transport were blocked by pretreatment with yohimbine, suggesting that alpha 2-adrenoceptors mediate the transport-related actions of this neurotransmitter. Serosal isoproterenol (0.1 microM) produced a tetrodotoxin-insensitive, propranolol-sensitive increase in the short-circuit current (Isc) in fundic tissues but not in tissues from the neck. The beta 2-adrenergic agonist salbutamol produced a response similar to that of isoproterenol. However, the beta 1-adrenergic agonist dobutamine had no effect. Isoproterenol was 5.8-fold more potent than salbutamol in increasing the Isc. A possible explanation for the regional effects of beta-agonists is that beta-adrenoceptors are localized to epithelial cells in the fundic region. These results and results obtained previously suggest regional differences in basal Na and Cl transport across the porcine gallbladder epithelium and that both alpha 2- and beta 2-adrenoceptors act to regulate ion transport in this tissue.

Regional differences in the response to platelet-activating factor in rabbit colon

1992 ◽  
Vol 82 (6) ◽  
pp. 673-680 ◽  
Author(s):  
S. P. L. Travis ◽  
D. P. Jewell
Keyword(s):  
Ion Transport ◽  
Regional Differences ◽  
Chloride Transport ◽  
Short Circuit ◽  
Platelet Activating Factor ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Chloride Secretion ◽  
Anion Secretion ◽  
Ussing Chambers

1. Platelet-activating factor is an inflammatory mediator related to eicosanoids which is known to stimulate anion secretion in the distal colon. Since there are regional differences in ion transport within the colon, the influence of platelet-activating factors on ion transport and epithelial permeability has been studied in rabbit caecum and distal colon mounted in Ussing chambers. 2. The effect of platelet-activating factor (1–50 nmol/l) on net electrogenic ion transport was to stimulate a biphasic increase in short-circuit current in the distal colon but not in the caecum. The platelet-activating factor-induced rise in short-circuit current was shown by ion replacement and pharmacological inhibitor studies to be consistent with chloride and bicarbonate secretion in the early phase, but with chloride secretion alone in the later phase. The effect on ion transport was specific and reversible and was enhanced by 0.25% BSA. 3. Colonic permeability, assessed by transmucosal resistance and mannitol flux, was increased by platelet-activating factor in both the distal colon and the caecum. This was consistent with an effect on platelet-activating factor on the paracellular pathway, because resistance decreased even when transcellular chloride transport was inhibited by frusemide or ion replacement. A specific platelet-activating factor antagonist (U66985) inhibited the effects of platelet-activating factor in both the distal colon and the caecum. 4. The results show that platelet-activating factor stimulates anion secretion only in the distal colon, but increases permeability in both the caecum and the distal colon.

Chloride transport inhibition by piretanide and MK-196 in bullfrog corneal epithelium

1981 ◽  
Vol 240 (1) ◽  
pp. F25-F29
Author(s):  
O. A. Candia ◽  
H. F. Schoen ◽  
L. Low ◽  
S. M. Podos
Keyword(s):  
Corneal Epithelium ◽  
Electrical Resistance ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Na Transport ◽  
Cl Transport ◽  
Apical Side ◽  
Diuretic Agents ◽  
Cl Permeability

Two new diuretic agents, piretanide and MK-196, inhibited short-circuit current (SCC) across the isolated frog corneal epithelium. The effect is explained as an inhibition of active Cl transport. A definite decrease in SCC and an increase in electrical resistance was observed with both diuretics in concentrations as low as 10(-6) M. Piretanide, at 10(-4) M, reduced the SCC by 90%, reduced th unidirectional forward Cl flux from 0.60 to 0.28 mueq x h-1 x cm-2, and increased the resistance by 60%. There was no effect on the Cl backflux. At 10(-4) M, MK-196 reduced the SCC by 83% and increased the resistance by 72%, from 1.68 to 2.91 k omega x cm2. Replacement of Cl by SO4 in the bathing solutions resulted in a larger increase in resistance, from 1.68 to 3.80 k omega x cm2. The diuretics had no effect on active Na transport across the corneal epithelium. After the permeability of the apical side was increased by amphotericin B, the drugs could not inhibit the Cl-originated SCC. These results suggest that piretanide and MK-196 selectively inhibit active Cl transport in the cornea by blocking Cl permeability of the apical side of the epithelial cells.

Protease-activated receptor-2 stimulates intestinal epithelial chloride transport through activation of PLC and selective PKC isoforms

2009 ◽  
Vol 296 (6) ◽  
pp. G1258-G1266 ◽  
Author(s):  
Jacques Q. van der Merwe ◽  
France Moreau ◽  
Wallace K. MacNaughton
Keyword(s):  
Serine Proteases ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Immunoblot Analysis ◽  
Chloride Secretion ◽  
Intestinal Epithelial ◽  
Ussing Chambers ◽  
Pkc Isoforms ◽  
Gf 109203X

Serine proteases play important physiological roles through their activity at G protein-coupled protease-activated receptors (PARs). We examined the roles that specific phospholipase (PL) C and protein kinase (PK) C (PKC) isoforms play in the regulation of PAR2-stimulated chloride secretion in intestinal epithelial cells. Confluent SCBN epithelial monolayers were grown on Snapwell supports and mounted in modified Ussing chambers. Short-circuit current ( Isc) responses to basolateral application of the selective PAR2 activating peptide, SLIGRL-NH2, were monitored as a measure of net electrogenic ion transport caused by PAR2 activation. SLIGRL-NH2 induced a transient Isc response that was significantly reduced by inhibitors of PLC (U73122), phosphoinositol-PLC (ET-18), phosphatidylcholine-PLC (D609), and phosphatidylinositol 3-kinase (PI3K; LY294002). Immunoblot analysis revealed the phosphorylation of both PLCβ and PLCγ following PAR2 activation. Pretreatment of the cells with inhibitors of PKC (GF 109203X), PKCα/βI (Gö6976), and PKCδ (rottlerin), but not PKCζ (selective pseudosubstrate inhibitor), also attenuated this response. Cellular fractionation and immunoblot analysis, as well as confocal immunocytochemistry, revealed increases of PKCβI, PKCδ, and PKCε, but not PKCα or PKCζ, in membrane fractions following PAR2 activation. Pretreatment of the cells with U73122, ET-18, or D609 inhibited PKC activation. Inhibition of PI3K activity only prevented PKCδ translocation. Immunoblots revealed that PAR2 activation induced phosphorylation of both cRaf and ERK1/2 via PKCδ. Inhibition of PKCβI and PI3K had only a partial effect on this response. We conclude that basolateral PAR2-induced chloride secretion involves activation of PKCβI and PKCδ via a PLC-dependent mechanism resulting in the stimulation of cRaf and ERK1/2 signaling.

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