Unique Regulation of Intestinal Villus Epithelial Cl−/HCO3− Exchange by Cyclooxygenase Pathway Metabolites of Arachidonic Acid in a Mouse Model of Spontaneous Ileitis

Electrolytes (NaCl) and fluid malabsorption cause diarrhea in inflammatory bowel disease (IBD). Coupled NaCl absorption, mediated by Na+/H+ and Cl−/HCO3− exchanges on the intestinal villus cells brush border membrane (BBM), is inhibited in IBD. Arachidonic acid metabolites (AAMs) formed via cyclooxygenase (COX) or lipoxygenase (LOX) pathways are elevated in IBD. However, their effects on NaCl absorption are not known. We treated SAMP1/YitFc (SAMP1) mice, a model of spontaneous ileitis resembling human IBD, with Arachidonyl Trifluoro Methylketone (ATMK, AAM inhibitor), or with piroxicam or MK-886, to inhibit COX or LOX pathways, respectively. Cl−/HCO3− exchange, measured as DIDS-sensitive 36Cl uptake, was significantly inhibited in villus cells and BBM vesicles of SAMP1 mice compared to AKR/J controls, an effect reversed by ATMK. Piroxicam, but not MK-886, also reversed the inhibition. Kinetic studies showed that inhibition was secondary to altered Km with no effects on Vmax. Whole cell or BBM protein levels of Down-Regulated in Adenoma (SLC26A3) and putative anion transporter-1 (SLC26A6), the two key BBM Cl−/HCO3− exchangers, were unaltered. Thus, inhibition of villus cell Cl−/HCO3− exchange by COX pathway AAMs, such as prostaglandins, via reducing the affinity of the exchanger for Cl−, and thereby causing NaCl malabsorption, could significantly contribute to IBD-associated diarrhea.

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Mechanism of regulation of rabbit intestinal villus cell brush border membrane Na/H exchange by nitric oxide

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00263.2005 ◽

2007 ◽

Vol 292 (2) ◽

pp. G475-G481 ◽

Cited By ~ 7

Author(s):

Steven Coon ◽

Guohong Shao ◽

Sheik Wisel ◽

Raju Vulaupalli ◽

Uma Sundaram

Keyword(s):

Nitric Oxide ◽

Brush Border ◽

Brush Border Membrane ◽

Kinetic Studies ◽

Protein Levels ◽

Nacl Absorption ◽

Exchange Kinetic ◽

Villus Cell ◽

Inhibitory Tone ◽

Inactive Analog

In the mammalian small intestine, coupled NaCl absorption occurs via the dual operation of Na/H and Cl/HCO3exchange on the villus cell brush border membrane (BBM). Although constitutive nitric oxide (cNO) has been demonstrated to alter gastrointestinal tract functions, how cNO may specifically alter these two transporters to regulate coupled NaCl absorption is unknown. In villus cells, inhibition of cNO synthase (cNOS) with l- NG-nitroarginine methylester (l-NAME) stimulated Na/H exchange whereas Cl/HCO3exchange was unaffected. In villus cell BBM vesicles (BBMV) prepared from rabbits treated with l-NAME, Na/H exchange was also stimulated. d-NAME, an inactive analog of l-NAME, and N6-(1-imonoethyl)-l-lysine dihydrochloride, a more selective inhibitor of inducible NO synthase, did not affect Na/H exchange. Kinetic studies demonstrated that the mechanism of stimulation is secondary to an increase in the maximal rate of uptake of Na, without an alteration in the affinity of the transporter for Na. Northern blot studies demonstrated an increase in the message for the BBM Na/H exchanger NHE3, and Western blot studies showed that the immunoreactive protein levels of NHE3 was increased when cNOS was inhibited. Thus these results indicate that cNO under nominal physiological states most likely maintains an inhibitory tone on small intestinal coupled NaCl absorption by specifically inhibiting BBM Na/H expression.

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Corticosteroids reverse the inhibition of Na-glucose cotransport in the chronically inflamed rabbit ileum

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1999.276.1.g211 ◽

1999 ◽

Vol 276 (1) ◽

pp. G211-G218 ◽

Cited By ~ 11

Author(s):

Uma Sundaram ◽

Steve Coon ◽

Sheik Wisel ◽

A. Brian West

Keyword(s):

Atpase Activity ◽

Brush Border Membrane ◽

Rabbit Model ◽

Membrane Vesicles ◽

Kinetic Studies ◽

Maximal Velocity ◽

Rabbit Ileum ◽

Protein Levels ◽

Mechanism Of Inhibition ◽

Villus Cell

In a rabbit model of chronic ileal inflammation, we previously demonstrated inhibition of Na-glucose cotransport (SGLT-1). The mechanism of inhibition was secondary to a decrease in the number of cotransporters and not solely secondary to an inhibition of Na-K-ATPase or altered affinity for glucose. In this study, we determined the effect of methylprednisolone (MP) on SGLT-1 inhibition during chronic ileitis. Treatment with MP almost completely reversed the reduction in SGLT-1 in villus cells from the chronically inflamed ileum. MP also reversed the decrease in Na-K-ATPase activity in villus cells during chronic ileitis. However, MP treatment reversed the SGLT-1 inhibition in villus cell brush-border membrane vesicles from the inflamed ileum, which suggested an effect of MP at the level of the cotransporter itself. Kinetic studies demonstrated that the reversal of SGLT-1 inhibition by MP was secondary to an increase in the maximal velocity for glucose without a change in the affinity. Analysis of immunoreactive protein levels of the cotransporter demonstrated a restoration of the cotransporter numbers after MP treatment in the chronically inflamed ileum. Thus MP treatment alleviates SGLT-1 inhibition in the chronically inflamed ileum by increasing the number of cotransporters and not solely secondary to enhancing the activity of Na-K-ATPase or by altering the affinity for glucose.

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Mechanism of inhibition of Na+-glucose cotransport in the chronically inflamed rabbit ileum

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1997.273.4.g913 ◽

1997 ◽

Vol 273 (4) ◽

pp. G913-G919 ◽

Cited By ~ 26

Author(s):

U. Sundaram ◽

S. Wisel ◽

V. M. Rajendren ◽

A. B. West

Keyword(s):

Steady State ◽

Brush Border Membrane ◽

Rabbit Model ◽

Kinetic Studies ◽

Maximal Rate ◽

Rabbit Ileum ◽

Intact Cells ◽

Protein Levels ◽

Mechanism Of Inhibition ◽

Villus Cell

In a rabbit model of chronic ileal inflammation, we previously demonstrated that coupled NaCl absorption was reduced because of an inhibition of Cl−/[Formula: see text]but not Na+/H+exchange on the brush-border membrane (BBM) of villus cells. In this study we determined the alterations in Na+-stimulated glucose [Na+- O-methyl-d-glucose (Na+-OMG)] absorption during chronic ileitis. Na+-OMG uptake was reduced in villus cells from the chronically inflamed ileum. Na+-K+-adenosinetriphosphatase (ATPase), which provides the favorable Na+gradient for this cotransporter in intact cells, was found to be reduced also. However, in villus cell BBM vesicles from the inflamed ileum Na+-OMG uptake was reduced as well, suggesting an effect at the level of the cotransporter itself. Kinetic studies demonstrated that Na+-OMG uptake in the inflamed ileum was inhibited by a decrease in the maximal rate of uptake for OMG without a change in the affinity. Analysis of steady-state mRNA and immunoreactive protein levels of this cotransporter demonstrates reduced expression. Thus Na+-glucose cotransport was inhibited in the chronically inflamed ileum, and the inhibition was secondary to a decrease in the number of cotransporters and not solely secondary to an inhibition of Na+-K+-ATPase or altered affinity for glucose.

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Mechanism of inhibition of Na+-bile acid cotransport during chronic ileal inflammation in rabbits

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1998.275.6.g1259 ◽

1998 ◽

Vol 275 (6) ◽

pp. G1259-G1265 ◽

Cited By ~ 12

Author(s):

U. Sundaram ◽

S. Wisel ◽

S. Stengelin ◽

W. Kramer ◽

V. Rajendran

Keyword(s):

Bile Acid ◽

Amino Acid ◽

Brush Border Membrane ◽

Rabbit Model ◽

Membrane Vesicles ◽

Kinetic Studies ◽

Transport Processes ◽

Protein Levels ◽

Mechanism Of Inhibition ◽

Villus Cell

In the chronically inflamed ileum, unique mechanisms of alteration of similar transport processes suggest regulation by different immune-inflammatory mediator pathways. In a rabbit model of chronic ileitis, we previously demonstrated that Na+-glucose cotransport was inhibited by a decrease in the cotransporter numbers, whereas Na+-amino acid cotransport was inhibited by a decrease in the affinity for the amino acid. In this study, we demonstrated that Na+-bile acid cotransport was reduced in villus cells from the chronically inflamed ileum. In villus cell brush-border membrane vesicles from the chronically inflamed ileum, Na+-bile acid cotransport was reduced as well, suggesting a direct effect at the cotransporter itself. Kinetic studies demonstrated that Na+-bile acid cotransport was inhibited by both a decrease in the affinity as well as a decrease in the maximal rate of uptake of the bile acid. Analysis of steady-state mRNA and immunoreactive protein levels of the Na+-bile acid cotransporter also demonstrated some reduction during chronic ileitis. Thus, in the chronically inflamed ileum, the mechanisms of inhibition of Na+-glucose, Na+-amino acid, and Na+-bile acid cotransport are different. These data suggest that different cotransporters are uniquely altered either secondary to their intrinsic differences or by different immune-inflammatory mediators during chronic ileitis.

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Inhibition of intestinal villus cell Na/K‐ATPase mediates altered glucose and NaCl absorption in obesity‐associated diabetes and hypertension

The FASEB Journal ◽

10.1096/fj.201802673r ◽

2019 ◽

Vol 33 (8) ◽

pp. 9323-9333 ◽

Cited By ~ 1

Author(s):

Balasubramanian Palaniappan ◽

Subha Arthur ◽

Vijaya Lakshmi Sundaram ◽

Molly Butts ◽

Shanmuga Sundaram ◽

...

Keyword(s):

Intestinal Villus ◽

Nacl Absorption ◽

Altered Glucose ◽

Villus Cell

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Na-glucose and Na-neutral amino acid cotransport are uniquely regulated by constitutive nitric oxide in rabbit small intestinal villus cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00124.2005 ◽

2005 ◽

Vol 289 (6) ◽

pp. G1030-G1035 ◽

Cited By ~ 15

Author(s):

Steven Coon ◽

James Kim ◽

Guohong Shao ◽

Uma Sundaram

Keyword(s):

Nitric Oxide ◽

Small Intestine ◽

Amino Acid ◽

Basolateral Membrane ◽

Kinetic Studies ◽

Mrna Levels ◽

Protein Levels ◽

Mechanism Of Inhibition ◽

Rabbit Small Intestine ◽

Villus Cell

Na-nutrient cotransport processes are not only important for the assimilation of essential nutrients but also for the absorption of Na in the mammalian small intestine. The effect of constitutive nitric oxide (cNO) on Na-glucose (SGLT-1) and Na-amino acid cotransport (NAcT) in the mammalian small intestine is unknown. Inhibition of cNO synthase with NG-nitro-l-arginine methyl ester (l-NAME) resulted in the inhibition of Na-stimulated 3H- O-methyl-d-glucose uptake in villus cells. However, Na-stimulated alanine uptake was not affected in these cells. The l-NAME-induced reduction in SGLT-1 in villus cells was not secondary to an alteration in basolateral membrane Na-K-ATPase activity, which provides the favorable Na gradient for this cotransport process. In fact, SGLT-1 was inhibited in villus cell brush-border membrane (BBM) vesicles prepared from animals treated with l-NAME. Kinetic studies demonstrated that the mechanism of inhibition of SGLT-1 was secondary to a decrease in the affinity for glucose without a change in the maximal rate of uptake of glucose. Northern blot studies demonstrated no change in the mRNA levels of SGLT-1. Western blot studies demonstrated no significant change in the immunoreactive protein levels of SGLT-1 in ileal villus cell BBM from l-NAME-treated rabbits. These studies indicate that inhibition of cNO production inhibits SGLT-1 but not NAcT in the rabbit small intestine. Therefore, whereas cNO promotes Na-glucose cotransport, it does not affect NAcT in the mammalian small intestine.

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Arachidonic acid metabolites and their role in inflammatory bowel disease

Gastroenterology ◽

10.1016/0016-5085(85)90525-6 ◽

1985 ◽

Vol 88 (2) ◽

pp. 580-587 ◽

Cited By ~ 118

Author(s):

Mark Donowitz

Keyword(s):

Inflammatory Bowel Disease ◽

Arachidonic Acid ◽

Bowel Disease ◽

Arachidonic Acid Metabolites ◽

Acid Metabolites ◽

Inflammatory Bowel

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The universe of arachidonic acid metabolites in inflammatory bowel disease

Current Opinion in Gastroenterology ◽

10.1097/mog.0000000000000075 ◽

2014 ◽

Vol 30 (4) ◽

pp. 347-351 ◽

Cited By ~ 18

Author(s):

William F. Stenson

Keyword(s):

Inflammatory Bowel Disease ◽

Arachidonic Acid ◽

Bowel Disease ◽

Arachidonic Acid Metabolites ◽

Acid Metabolites ◽

Inflammatory Bowel ◽

The Universe

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Mast Cell Mediated Regulation of Small Intestinal Chloride Malabsorption in SAMP1/YitFc Mouse Model of Spontaneous Chronic Ileitis

Cells ◽

10.3390/cells10030697 ◽

2021 ◽

Vol 10 (3) ◽

pp. 697

Author(s):

M Motiur Rahman ◽

Sheuli Afroz ◽

Subha Arthur ◽

Uma Sundaram

Keyword(s):

Mast Cell ◽

Mast Cells ◽

Brush Border Membrane ◽

Kinetic Studies ◽

Marker Enzyme ◽

Mice Model ◽

Experimental Conditions ◽

Inflammatory Bowel ◽

Small Intestinal ◽

Akr Mice

In Inflammatory Bowel Disease (IBD), malabsorption of electrolytes (NaCl) results in diarrhea. Inhibition of coupled NaCl absorption, mediated by the dual operation of Na:H and Cl:HCO3 exchangers on the brush border membrane (BBM) of the intestinal villus cells has been reported in IBD. In the SAMP1/YitFcs (SAMP1) mice model of spontaneous ileitis, representing Crohn’s disease, DRA (Downregulated in Adenoma) mediated Cl:HCO3 exchange was shown to be inhibited secondary to diminished affinity of the exchanger for Cl. However, NHE3 mediated Na:H exchange remained unaffected. Mast cells and their secreted mediators are known to be increased in the IBD mucosa and can affect intestinal electrolyte absorption. However, how mast cell mediators may regulate Cl:HCO3 exchange in SAMP1 mice is unknown. Therefore, the aim of this study was to determine the effect of mast cell mediators on the downregulation of DRA in SAMP1 mice. Mast cell numbers and their degranulation marker enzyme (β-hexosaminidase) levels were significantly increased in SAMP1 mice compared to control AKR mice. However, treatment of SAMP1 mice with a mast cell stabilizer, ketotifen, restored the β-hexosaminidase enzyme levels to normal in the intestine, demonstrating stabilization of mast cells by ketotifen. Moreover, downregulation of Cl:HCO3 exchange activity was restored in ketotifen treated SAMP1 mice. Kinetic studies showed that ketotifen restored the altered affinity of Cl:HCO3 exchange in SAMP1 mice villus cells thus reinstating its activity to normal. Further, RT-qPCR, Western blot and immunofluorescence studies showed that the expression levels of DRA mRNA and BBM protein, respectively remained unaltered in all experimental conditions, supporting the kinetic data. Thus, inhibition of Cl:HCO3 exchange resulting in chloride malabsorption leading to diarrhea in IBD is likely mediated by mast cell mediators.

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