Segment-specific effects of epinephrine on ion transport in the colon of the rat

The effect of epinephrine on transport of K+, Na+, Cl−, and[Formula: see text] across the rat colon was studied using the Ussing chamber technique. Epinephrine (5 × 10−6mol/l) induced a biphasic change in short-circuit current ( Isc) in distal and proximal colon: a transient increase followed by a long-lasting decay. The first phase of the Iscresponse was abolished in Cl−-poor solution or after bumetanide administration, indicating a transient induction of Cl−secretion. The second phase of the response to epinephrine was suppressed by apical administration of the K+channel blocker, quinine, and was concomitant with an increase in serosal-to-mucosal Rb+flux, indicating that epinephrine induced K+secretion, although this response was much smaller than the change in Isc. In addition, the distal colon displayed a decrease in mucosal-to-serosal and serosal-to-mucosal Cl−fluxes when treated with epinephrine. In the distal colon, indomethacin abolished the first phase of the epinephrine effect, whereas the second phase was suppressed by TTX. In the proximal colon, indomethacin and TTX were ineffective. The neuronally mediated response to epinephrine in the distal colon was suppressed by the nonselective β-receptor blocker, propranolol, and by the β2-selective blocker, ICI-118551, whereas the epithelial response in the proximal colon was suppressed by the nonselective α-blocker, phentolamine, and by the selective α2-blocker, yohimbine. These results indicate a segment-specific action of epinephrine on ion transport: a direct stimulatory action on epithelial α2-receptors in the proximal colon and an indirect action on secretomotoneurons via β2-receptors in the distal colon.

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Dietary flavonol quercetin induces chloride secretion in rat colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1998.275.5.g1166 ◽

1998 ◽

Vol 275 (5) ◽

pp. G1166-G1172 ◽

Cited By ~ 7

Author(s):

Rainer Cermak ◽

Ursula Föllmer ◽

Siegfried Wolffram

Keyword(s):

Short Circuit ◽

Ussing Chamber ◽

Phosphodiesterase Inhibitor ◽

Short Circuit Current ◽

Distal Colon ◽

Chloride Secretion ◽

Proximal Colon ◽

Rat Colon ◽

Quercetin Glycoside

The aim of this study was to investigate the possible effects of the flavonol quercetin, the most abundant dietary flavonoid, on the intestinal mucosa. In vitro experiments were performed with various segments of the rat intestine, using the Ussing chamber technique. Quercetin increased the short-circuit current ( I sc) in the jejunum, ileum, and proximal and distal colon. Additional experiments were performed using preparations of the proximal colon. The maximum effective dose of quercetin was found to be ∼100 μM. The quercetin-induced increase in I sc was inhibited by the Cl− channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid. Adding blockers of the Na+-K+-2Cl−cotransporter to the serosal compartment diminished the increase of I sc due to quercetin. Ion substitution and flux measurements indicated that the effect of quercetin was due to electrogenic Cl− and[Formula: see text] secretion. In contrast to the aglycone, the quercetin glycoside rutin had no effect. The effect of quercetin on I scwas additive to the I sc increase induced by forskolin, but the flavonoid diminished the I sc evoked by carbachol. The phosphodiesterase inhibitor theophylline blocked the effect of quercetin. Genistein, a related isoflavone, did not alter the I sc evoked by quercetin. These findings demonstrate that the dietary flavonol quercetin induces Cl−secretion and most likely [Formula: see text]secretion in rat small and large intestine. The effects are restricted to the flavonol aglycone.

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Cyclic nucleotide-gated cation channels mediate sodium and calcium influx in rat colon

AJP Cell Physiology ◽

10.1152/ajpcell.2000.278.2.c336 ◽

2000 ◽

Vol 278 (2) ◽

pp. C336-C343 ◽

Cited By ~ 13

Author(s):

W. Qiu ◽

B. Lee ◽

M. Lancaster ◽

W. Xu ◽

S. Leung ◽

...

Keyword(s):

Cyclic Nucleotide ◽

Calcium Absorption ◽

Calcium Influx ◽

Short Circuit ◽

Short Circuit Current ◽

Distal Colon ◽

Proximal Colon ◽

Cation Channels ◽

Rat Colon ◽

Sodium Absorption

We found mRNA for the three isoforms of the cyclic nucleotide-gated nonselective cation channel expressed in the mucosal layer of the rat intestine from the duodenum to the colon and in intestinal epithelial cell lines in culture. Because these channels are permeable to sodium and calcium and are stimulated by cGMP or cAMP, we measured 8-bromo-cGMP-stimulated sodium-mediated short-circuit current ( I sc) in proximal and distal colon and unidirectional45Ca2+fluxes in proximal colon to determine whether these channels could mediate transepithelial sodium and calcium absorption across the colon. Sodium-mediated I sc, stimulated by 8-bromo-cGMP, were inhibited by dichlorobenzamil and l-cis-diltiazem, blockers of cyclic nucleotide-gated cation channels, suggesting that these ion channels can mediate transepithelial sodium absorption. Sodium-mediated I sc and net transepithelial45Ca2+absorption were stimulated by heat-stable toxin from Escherichia coli that increases cGMP. Addition of l-cis-diltiazem inhibited the enhanced transepithelial absorption of both ions. These results suggest that cyclic nucleotide-gated cation channels simultaneously increase net sodium and calcium absorption in the colon of the rat.

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Effects of carbon monoxide on ion transport across rat distal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00407.2010 ◽

2011 ◽

Vol 300 (2) ◽

pp. G207-G216 ◽

Cited By ~ 11

Author(s):

Julia Steidle ◽

Martin Diener

Keyword(s):

Carbon Monoxide ◽

Ion Transport ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Distal Colon ◽

Disulfonic Acid ◽

Maximal Response ◽

Colonic Crypts ◽

Acid Sodium Salt

The aim of the present study was to investigate whether carbon monoxide (CO) induces changes in ion transport across the distal colon of rats and to study the mechanisms involved. In Ussing chamber experiments, tricarbonyldichlororuthenium(II) dimer (CORM-2), a CO donor, evoked a concentration-dependent increase in short-circuit current ( Isc). A maximal response was achieved at a concentration of 2.5·10−4 mol/l. Repeated application of CORM-2 resulted in a pronounced desensitization of the tissue. Anion substitution experiments suggest that a secretion of Cl− and HCO3− underlie the CORM-2-induced current. Glibenclamide, a blocker of the apical cystic fibrosis transmembrane regulator channel, inhibited the Isc induced by the CO donor. Similarly, bumetanide, a blocker of the basolateral Na+-K+-2Cl− cotransporter, combined with 4-acetamido-4′-isothiocyanato-stilbene-2,2′-disulfonic acid sodium salt, an inhibitor of the basolateral Cl−/HCO3− exchanger, inhibited the CORM-2-induced Isc. Membrane permeabilization experiments indicated an activation of basolateral K+ and apical Cl− channels by CORM-2. A partial inhibition by the neurotoxin, tetrodotoxin, suggests the involvement of secretomotor neurons in this response. In imaging experiments at fura-2-loaded colonic crypts, CORM-2 induced an increase of the cytosolic Ca2+ concentration. This increase depended on the influx of extracellular Ca2+, but not on the release of Ca2+ from intracellular stores. Both enzymes for CO production, heme oxygenase I and II, are expressed in the colon as observed immunohistochemically and by RT-PCR. Consequently, endogenous CO might be a physiological modulator of colonic ion transport.

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Steroids alter ion transport and absorptive capacity in proximal and distal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1985.249.1.g113 ◽

1985 ◽

Vol 249 (1) ◽

pp. G113-G119 ◽

Cited By ~ 1

Author(s):

J. H. Sellin ◽

R. C. DeSoignie

Keyword(s):

Ion Transport ◽

Absorptive Capacity ◽

Short Circuit ◽

Short Circuit Current ◽

Distal Colon ◽

Proximal Colon ◽

High Rate ◽

Transport Parameters ◽

In Vitro Effects

Steroids are potent absorbagogues, increasing Na and fluid absorption in a variety of epithelia. This study characterizes the in vitro effects of pharmacological doses of gluco- and mineralocorticoids on transport parameters of rabbit proximal and distal colon. Treatment with methylprednisolone (MP, 40 mg im for 2 days) and desoxycortone acetate (DOCA, 12.5 mg im for 3 days) resulted in a significant increase in short-circuit current (Isc) in distal colon, suggesting an increase in basal Na absorption. Amiloride (10(-4) M) caused a significantly negative Isc in MP-treated tissue, demonstrating a steroid-induced, amiloride-insensitive electrogenic ion transport in distal colon. The effect of two absorbagogues, impermeant anions (SO4-Ringer) and amphotericin, were compared in control and steroid-treated distal colon. In controls, both absorbagogues increased Isc. Impermeant anions caused a rise in Isc in both MP and DOCA tissues, suggesting that the high rate of basal Na absorption had not caused a saturation of the Na pump. The steroid-treated colons, however, did not consistently respond to amphotericin. Amiloride inhibited the entire Isc in MP-treated distal colon that had been exposed to amphotericin; this suggested that amphotericin had not exerted its characteristic effect on the apical membrane of steroid-treated colon. In proximal colon, steroids did not alter basal rates of transport; however, epinephrine-induced Na-Cl absorption was significantly greater in MP-treated vs control (P less than 0.005). Steroids increase the absorptive capacity of both proximal and distal colon for Na, while increasing basal Na absorption only in the distal colon.(ABSTRACT TRUNCATED AT 250 WORDS)

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Site-specific regulation of ion transport by prolactin in rat colon epithelium

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00143.2011 ◽

2012 ◽

Vol 302 (10) ◽

pp. G1199-G1206 ◽

Cited By ~ 3

Author(s):

Chatsri Deachapunya ◽

Sutthasinee Poonyachoti ◽

Nateetip Krishnamra

Keyword(s):

Ion Transport ◽

Kinase Inhibitor ◽

Short Circuit ◽

Specific Effect ◽

Distal Colon ◽

Proximal Colon ◽

Rat Colon ◽

Channel Blockers ◽

Phosphatidylinositol 3 Kinase ◽

Phosphatidylinositol 3

The effect of prolactin (PRL) on ion transport across the rat colon epithelium was investigated using Ussing chamber technique. PRL (1 μg/ml) induced a sustained decrease in short-circuit current ( Isc) in the distal colon with an EC50 value of 100 ng/ml and increased Isc in the proximal colon with an EC50 value of 49 ng/ml. In the distal colon, the PRL-induced decrease in Isc was not affected by Na+ channel blocker amiloride or Cl− channel blockers, NPPB, DPC, or DIDS, added mucosally. However, the response was inhibited by mucosal application of K+ channel blockers glibenclamide, quinidine, and chromanol 293B, whereas other K+ channel blockers, Ba2+, tetraethylammonium, clotrimazole, and apamin, failed to have effects. The PRL-induced decrease in Isc was also inhibited by Na+-K+-2Cl− transporter inhibitor bumetanide, Ba2+, and chromanol 293B applied serosally. In the transverse and proximal colon, the PRL-induced increase in Isc was suppressed by DPC, glibenclamide, and bumetanide, but not by NPPB, DIDS, or amiloride. The PRL-induced changes in Isc in both distal and proximal colon were abolished by JAK2 inhibitor AG490, but not BAPTA-AM, the Ca2+ chelating agent, or phosphatidylinositol 3-kinase inhibitor wortmannin. These results suggest a segment-specific effect of PRL in rat colon, by activation of K+ secretion in the distal colon and activation of Cl− secretion in the transverse and proximal colon. Both PRL actions are mediated by JAK-STAT-dependent pathway, but not phosphatidylinositol 3-kinase pathway or Ca2+ mobilization. These findings suggest a role of PRL in the regulation of electrolyte transport in mammalian colon.

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Control of electrogenic Na+ absorption in rat late distal colon by nanomolar aldosterone added in vitro

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1993.264.1.e68 ◽

1993 ◽

Vol 264 (1) ◽

pp. E68-E73 ◽

Cited By ~ 10

Author(s):

M. Fromm ◽

J. D. Schulzke ◽

U. Hegel

Keyword(s):

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Distal Colon ◽

Proximal Colon ◽

Hill Coefficient ◽

Late Response ◽

Maximal Velocity ◽

Time Courses

It has been possible to obtain in a mammalian epithelium of dietetically and surgically untreated animals a dose response of in vitro-added aldosterone (Aldo, 10(-10) to 10(-5) M) on electrogenic Na+ absorption (JeNa). JeNa was measured in the Ussing chamber on stripped rat late distal colon 8 h after in vitro addition of Aldo. Submaximal effects were obtained at 3 nM Aldo; after a lag time of 2 h, short-circuit current (Isc) increased to a maximum of 234 +/- 15 microA/cm2 and dropped after 0.1 mM amiloride to -18 +/- 3 microA/cm2, resulting in JeNa of 9.4 +/- 0.6 mumol.h-1 x cm-1. Net Na+ tracer fluxes and Isc exhibited parallel time courses, so that electroneutral Na+ transport was not induced in late distal colon by acute Aldo. A plot of JeNa vs. Na conductance revealed an electromotive force (ENa) of 126 +/- 1 mV for all Aldo concentrations tested. Kinetic data were as follows: Michaelis constant 1.2 nM, maximal velocity (Vmax) 10.5 mumol.h-1 x cm-2, and Hill coefficient 2.1. In contrast to the large effect in late distal colon, 3 nM Aldo caused JeNa of < 1 mumol.h-1 x cm-2 in early distal colon, proximal colon, and cecum. Antimineralocorticoid sensitivity and ENa did not vary with Aldo concentration or time of the experiment, consistent with a unique mechanism during the early and late response up to 8 h, as well as at mineralocorticoid and glucocorticoid Aldo concentrations. Acute Aldo in a range of 0.1–10 nM fully controls JeNa between zero and Vmax in late distal colon.(ABSTRACT TRUNCATED AT 250 WORDS)

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Basolateral Cl− uptake mechanisms in Xenopus laevis lung epithelium

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00749.2009 ◽

2010 ◽

Vol 299 (1) ◽

pp. R92-R100 ◽

Cited By ~ 3

Author(s):

Jens Berger ◽

Martin Hardt ◽

Wolfgang G. Clauss ◽

Martin Fronius

Keyword(s):

Xenopus Laevis ◽

Ion Transport ◽

Anion Exchanger ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Transport Processes ◽

Lung Epithelium ◽

Active Ion Transport ◽

Uptake Mechanisms

A thin liquid layer covers the lungs of air-breathing vertebrates. Active ion transport processes via the pulmonary epithelial cells regulate the maintenance of this layer. This study focuses on basolateral Cl− uptake mechanisms in native lungs of Xenopus laevis and the involvement of the Na+/K+/2 Cl− cotransporter (NKCC) and HCO3−/Cl− anion exchanger (AE), in particular. Western blot analysis and immunofluorescence staining revealed the expression of the NKCC protein in the Xenopus lung. Ussing chamber experiments demonstrated that the NKCC inhibitors (bumetanide and furosemide) were ineffective at blocking the cotransporter under basal conditions, as well as under pharmacologically stimulated Cl−-secreting conditions (forskolin and chlorzoxazone application). However, functional evidence for the NKCC was detected by generating a transepithelial Cl− gradient. Further, we were interested in the involvement of the HCO3−/Cl− anion exchanger to transepithelial ion transport processes. Basolateral application of DIDS, an inhibitor of the AE, resulted in a significantly decreased the short-circuit current (ISC). The effect of DIDS was diminished by acetazolamide and reduced by increased external HCO3− concentrations. Cl− secretion induced by forskolin was decreased by DIDS, but this effect was abolished in the presence of HCO3−. These experiments indicate that the AE at least partially contributes to Cl− secretion. Taken together, our data show that in Xenopus lung epithelia, the AE, rather than the NKCC, is involved in basolateral Cl− uptake, which contrasts with the common model for Cl− secretion in pulmonary epithelia.

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Enterohemorrhagic E. coli (EHEC)—Secreted Serine Protease EspP Stimulates Electrogenic Ion Transport in Human Colonoid Monolayers

Toxins ◽

10.3390/toxins10090351 ◽

2018 ◽

Vol 10 (9) ◽

pp. 351 ◽

Cited By ~ 3

Author(s):

C. Tse ◽

Julie In ◽

Jianyi Yin ◽

Mark Donowitz ◽

Michele Doucet ◽

...

Keyword(s):

Ion Transport ◽

Serine Protease ◽

Shiga Toxin ◽

Short Circuit ◽

Ussing Chamber ◽

Adult Stem Cell ◽

Short Circuit Current ◽

Watery Diarrhea ◽

E Coli ◽

Electrogenic Ion Transport

One of the characteristic manifestations of Shiga-toxin-producing Escherichia coli (E. coli) infection in humans, including EHEC and Enteroaggregative E. coli O104:H4, is watery diarrhea. However, neither Shiga toxin nor numerous components of the type-3 secretion system have been found to independently elicit fluid secretion. We used the adult stem-cell-derived human colonoid monolayers (HCM) to test whether EHEC-secreted extracellular serine protease P (EspP), a member of the serine protease family broadly expressed by diarrheagenic E. coli can act as an enterotoxin. We applied the Ussing chamber/voltage clamp technique to determine whether EspP stimulates electrogenic ion transport indicated by a change in short-circuit current (Isc). EspP stimulates Isc in HCM. The EspP-stimulated Isc does not require protease activity, is not cystic fibrosis transmembrane conductance regulator (CFTR)-mediated, but is partially Ca2+-dependent. EspP neutralization with a specific antibody reduces its potency in stimulating Isc. Serine Protease A, secreted by Enteroaggregative E. coli, also stimulates Isc in HCM, but this current is CFTR-dependent. In conclusion, EspP stimulates colonic CFTR-independent active ion transport and may be involved in the pathophysiology of EHEC diarrhea. Serine protease toxins from E. coli pathogens appear to serve as enterotoxins, potentially significantly contributing to watery diarrhea.

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Flupirtine enhances NHE-3 mediated Na+ absorption in rat colon via an ENS-dependent mechanism

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00158.2021 ◽

2021 ◽

Author(s):

Andrew J. Nickerson ◽

Vazhaikkurichi M. Rajendran

Keyword(s):

Immunofluorescence Microscopy ◽

Short Circuit ◽

Short Circuit Current ◽

Proximal Colon ◽

Selective Inhibitor ◽

Rat Colon ◽

Pre Treatment ◽

Apical Membranes ◽

Microscopy Techniques ◽

Dependent Mechanism

Recent studies in our lab have shown that the KV7 channel activator, flupirtine, inhibits colonic epithelial Cl- secretion through effects on submucosal neurons of the enteric nervous system (ENS). We hypothesized that flupirtine would also stimulate Na+ absorption as a result of reduced secretory ENS input to the epithelium. To test this hypothesis, unidirectional 22Na+ fluxes were measured under voltage-clamped conditions. Pharmacological approaches using an Ussing-style recording chamber, combined immunofluorescence microscopy techniques were used to determine the effect of flupirtine on active Na+ transport in the rat colon. Flupirtine stimulated electroneutral Na+ absorption in partially seromuscular stripped colonic tissues, while simultaneously inhibiting short circuit current (ISC; i.e., Cl- secretion). Both of these effects were attenuated by pre-treatment with the ENS inhibitor, tetrodotoxin. The NHE-3-selective inhibitor, S3226, significantly inhibited flupirtine-stimulated Na+ absorption whereas the NHE-2-selective inhibitor HOE-694 did not. NHE-3 localization near the apical membranes of surface epithelial cells was also more apparent in flupirtine-treated colon versus control. Flupirtine did not alter epithelial Na+ channel (ENaC)-mediated Na+ absorption in distal colonic tissues obtained from hyperaldosteronaemic rats and had no effect in the normal ileum, but did stimulate Na+ absorption in the proximal colon. Finally, the parallel effects of flupirtine on ISC (Cl- secretion) and Na+ absorption were significantly correlated with each other. Together, these data indicate that flupirtine stimulates NHE-3-dependent Na+ absorption, likely as a result of reduced stimulatory input to the colonic epithelium by submucosal ENS neurons.

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Ion transport by neonatal rabbit distal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1986.250.6.g754 ◽

1986 ◽

Vol 250 (6) ◽

pp. G754-G759 ◽

Cited By ~ 4

Author(s):

G. D. Potter ◽

S. M. Burlingame

Keyword(s):

Small Intestine ◽

Short Circuit ◽

Ussing Chamber ◽

Electrical Conductance ◽

Short Circuit Current ◽

Distal Colon ◽

Ion Fluxes ◽

Adult Rabbit ◽

Rabbit Colon ◽

Edge Damage

The neonatal small intestine is characterized by electrical conductance and permeability to ions higher than in the corresponding adult intestine. To investigate whether this property of the neonate is limited to the small intestine, or extends to the colon, a modified Ussing chamber for determination of transmucosal potential difference (PD), short-circuit current (Isc), transepithelial conductance (Gt), and ion fluxes in the neonatal rabbit distal colon was constructed. After care to reduce edge damage, Gt for the neonatal colon was found to be 8.4 +/- 0.3 mS . cm2 and for adult colon in the same chamber, 7.4 +/- 0.5 (P greater than 0.05). Net Na and Cl fluxes under short-circuit conditions were similar to those obtained in adult colon. Unidirectional ion fluxes were also similar to those of the adult. Net Na flux (JNanet) was incompletely inhibited by 10(-4) M of amiloride. Response to replacement of Na, Cl, and HCO3-, respectively, in the bathing solutions was not different from that expected in adult rabbit colon. Thus differences between adult and neonatal rabbit colon were small, and the increased conductance and unidirectional ion fluxes characteristic of the neonatal small intestine were not evident in the neonatal rabbit distal colon.

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