scholarly journals Transepithelial glucose transport in the small intestine

2020 ◽  
Vol 51 (6) ◽  
pp. 673-686
Author(s):  
Mirela Pavić ◽  
Marija Ljubojević ◽  
Ivona Žura Žaja ◽  
Ivana Prakatur ◽  
Manuela Grčević ◽  
...  
Keyword(s):  
Small Intestine ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Glucose Transporter ◽  
Enzymatic Digestion ◽  
Transepithelial Transport ◽  
Facilitated Diffusion ◽  
Glucose Transporter 2 ◽  
Complex Carbohydrates

The duodenum, jejunum and ileum are parts of the small intestine and the sites of the terminal stages of enzymatic digestion, and the majority of nutrient, electrolyte and water absorption. The apical, luminal membrane of the enterocyte is built of numerous microvilli that increase the absorptive surface of the cell. Carbohydrates, in the form of monosaccharides, oligosaccharides and especially polysaccharides, make up the largest quantitative and energetic part of the diet of most animals, including humans. Galactose, fructose and glucose, the final degradation products of polysaccharide and oligosaccharide enzymatic digestion, can be absorbed by enterocytes either by active transport or by facilitated diffusion. In the small intestine, the transepithelial transport of glucose, the most abundant monosaccharide after carbohydrate digestion and the main source of energy, is performed by a specific membrane transporter located in the brush border membrane of the enterocyte, the sodiumglucose cotransporter 1 (SGLT1). While SGLT1 transports glucose across the brush border membrane, a specific basolateral membrane glucose transporter, the sodium-independent glucose transporter 2 (GLUT2), transfers glucose out of the enterocyte down the concentration gradient. The sodium-potassium pump (Na/KATPase), as a sodium and potassium ion transporter, is functionally closely related to the sodium-dependent SGLT1. Na/KATPase is responsible for maintaining the electrochemical gradient of sodium ions, as the driving force for glucose transport via SGLT1. Transepithelial transport of glucose in the small intestine and the differentiation of enterocytes occurs relatively early during the foetal period, allowing glucose to be absorbed from ingested amniotic fluid. Nutrient transport is possible along the whole villus-crypt axis during intrauterine development, while transport shifts toward the villus tip in the mature small intestine. With maturation, glucose transport rates change not only across the villus-crypt axis, but also along the proximodistal axis in the small intestine. The glucose absorption rate shows differences between subunits of the small intestine depending on the age and type of ingested carbohydrates, where complex carbohydrates replace less complex carbohydrates or disaccharides.

scholarly journals Renal Glycosuria as a Novel Early Sign of Colistin-Induced Kidney Damage in Mice

2019 ◽  
Vol 63 (12) ◽  
Author(s):  
Sophia L. Samodelov ◽  
Michele Visentin ◽  
Zhibo Gai ◽  
Stephanie Häusler ◽  
Gerd A. Kullak-Ublick
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Glucose Transporter ◽  
Ex Vivo ◽  
Kidney Injury ◽  
Direct Interaction ◽  
Protein Quantification ◽  
Clinical Markers ◽  
Drug Induced ◽  
Glucose Transporter 2

ABSTRACT The polymyxin colistin represents a last-resort antibiotic for multidrug-resistant infections, but its use is limited by the frequent onset of acute drug-induced kidney injury (DIKI). It is essential to closely monitor kidney function prior to and during colistin treatment in order to pinpoint early signs of injury and minimize long-term renal dysfunction. To facilitate this, a mouse model of colistin-induced nephrotoxicity was used to uncover novel early markers of colistin-induced DIKI. Increased urinary levels of kidney injury molecule-1 (Kim-1) as well as glycosuria were observed in colistin-treated mice, where alterations of established clinical markers of acute kidney injury (serum creatinine and albuminuria) and emerging markers such as cystatin C were inaccurate in flagging renal damage as confirmed by histology. A direct interaction of colistin with renal glucose reabsorption was ruled out by a cis-inhibition assay in mouse brush border membrane vesicles (BBMV). Immunohistochemical examination and protein quantification by Western blotting showed a marked reduction in the protein amount of sodium-glucose transporter 2 (Sglt2), the main kidney glucose transporter, in renal tissue from colistin-treated mice in comparison to that in control animals. Consistently, BBMV isolated from treated mouse kidneys also showed a reduction in ex vivo glucose uptake compared to that in BBMV isolated from control kidneys. These findings support pathology observations of colistin-induced proximal tubule damage at the site of the brush border membrane, where Sglt2 is expressed, and open avenues for the study of glycosuria as a sensitive, specific, and accessible marker of DIKI during colistin therapy.

Effect of chronic cold exposure on Na-dependent D-glucose transport along small intestine in ducklings

1996 ◽  
Vol 271 (5) ◽  
pp. R1429-R1438
Author(s):  
V. Thomas ◽  
B. Pichon ◽  
G. Crouzoulon ◽  
H. Barre
Keyword(s):  
Small Intestine ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Cold Exposure ◽  
Brush Border ◽  
Brush Border Membrane ◽  
High Energy ◽  
Cold Effect ◽  
High Affinity ◽  
High Affinity Site

In conditions of chronic cold exposure, ducklings develop a nonshivering thermogenesis that requires a high energy expenditure. Therefore, energy supply becomes essential to cold-acclimated ducklings, which increase their intake of carbohydrate-rich food. The aim of this work was to investigate the effect of cold acclimation on the activity of the intestinal brush-border Na(+)-D-glucose cotransport, which is the first major step controlling glucose entrance into an organism. Cotransport activity was determined by measuring D-glucose uptake in brush-border membrane vesicles isolated from different parts of the small intestine of thermoneutral control (25 degrees C) or cold-acclimated (4 degrees C) ducklings (Cairina moschata). Two D-glucose transport sites were described in ducklings: a high-affinity/low-capacity site and a low-affinity/high-capacity site. The former was mainly located in the ileum and the latter in the duodenum. These two transport sites were altered differently by cold exposure. Major alterations occur in the ileum where 1) a reduction in the Michaelis-Menten constant and maximal transport rate of the high-affinity site was observed, and 2) the occurrence of low-affinity site activity was noted in cold-acclimated ducklings, although it was not detected in the thermoneutral control group. Cold effect on the high-affinity site could be related to the changes in the ileal brush-border membrane vesicle lipids, whereas cold effect on the low-affinity site could be due, at least in part, to the higher glycosyl content found in this segment. The small intestine appears then able to react to cold exposure by increasing both its mucosa mass in proximal segments and D-glucose uptake capacity in ileum to respond to the higher energy demand induced by thermoregulatory requirements.

Oral polyamine administration modifies the ontogeny of hexose transporter gene expression in the postnatal rat intestine

2007 ◽  
Vol 293 (2) ◽  
pp. G453-G460 ◽  
Author(s):  
G. E. Wild ◽  
L. E. Searles ◽  
K. G. Koski ◽  
L. A. Drozdowski ◽  
J. Begum-Hasan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Glucose Transporter ◽  
Basolateral Membrane ◽  
Glucose Transporter 1 ◽  
Sugar Transporters ◽  
Enterocyte Proliferation ◽  
Glucose Transporter 2 ◽  
Postnatal Rats

Gastrointestinal mucosal polyamines influence enterocyte proliferation and differentiation during small intestinal maturation in the rat. Studies in postnatal rats have shown that ornithine decarboxylase (ODC) protein and mRNA peak before the maximal expression of brush-border membrane (BBM) sucrase-isomaltase (SI) and the sugar transporters sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2). This study was undertaken to test the hypothesis that the oral administration of spermidine in postnatal rats upregulates the expression of ODC, thereby enhancing the expression of SI and SGLT1 in the brush-border membrane as well as basolateral membrane-facilitative GLUT2 and Na+-K+-ATPase. Northern and Western blot analyses were performed with antibodies and cDNA probes specific for SI, SGLT1, GLUT2, α1- and β1-subunits of Na+-K+-ATPase, and ODC. Postnatal rats fed 6 μmol spermidine daily for 3 days from days 7 to 9 were killed either on postnatal day 10 (Sp10) or day 13 following a 3-day washout period (Sp13). Sp10 rats showed a precocious increase in the abundance of mRNAs for SI, SGLT1, and GLUT2 and Na+-K+-ATPase activity and α1- and β1-isoform gene expression compared with controls. ODC activity and protein and mRNA abundance were also increased in Sp10 animals. The increased expression of these genes was not sustained in Sp13 rats, suggesting that these effects were transient. Thus, 3 days of oral polyamine administration induces the precocious maturation of glucose transporters in the postnatal rat small intestine, which may be mediated by alterations in ODC expression. 1 1 Supplemental material for this article is available online at the American Journal of Physiology-Gastrointestinal and Liver Physiology website.

scholarly journals The apical (hPepT1) and basolateral peptide transport systems of Caco-2 cells are regulated by AMP-activated protein kinase

2010 ◽  
Vol 299 (1) ◽  
pp. G136-G143 ◽  
Author(s):  
Myrtani Pieri ◽  
Helen C. Christian ◽  
Robert J. Wilkins ◽  
C. A. R. Boyd ◽  
David Meredith
Keyword(s):  
Electron Microscopy ◽  
Protein Kinase ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Glucose Transporter ◽  
Peptide Transport ◽  
Transport Systems ◽  
Immunogold Electron Microscopy ◽  
Glucose Transporter 2 ◽  
Amp Activated Protein Kinase

The effect of 5-aminoimidazole-4-carboxamide-ribonucleoside (AICAR) activation of the AMP-activated protein kinase (AMPK) on the transport of the model radiolabeled dipeptide [3H]-D-Phe-L-Gln was investigated in the human epithelial colon cancer cell line Caco-2. Uptake and transepithelial fluxes of [3H]-D-Phe-L-Gln were carried out in differentiated Caco-2 cell monolayers, and hPepT1 and glucose transporter 2 (GLUT2) protein levels were quantified by immunogold electron microscopy. AICAR treatment of Caco-2 cells significantly inhibited apical [3H]-D-Phe-L-Gln uptake, matched by a decrease in brush-border membrane hPepT1 protein but with a concomitant increase in the facilitated glucose transporter GLUT2. A restructuring of the apical brush-border membrane was seen by electron microscopy. The hPepT1-mediated transepithelial (A-to-B) peptide flux across the Caco-2 monolayers showed no significant alteration in AICAR-treated cells. The electrical resistance in the AICAR-treated monolayers was significantly higher compared with control cells. Inhibition of the sodium/hydrogen exchanger 3 (NHE3) had an additive effect to AICAR, suggesting that the AMPK effect is not via NHE3. Fluorescence measurement of intracellular pH showed no reduction in the proton gradient driving PepT1-mediated apical uptake. The reduction in apical hPepT1 protein and dipeptide uptake after AICAR treatment in Caco-2 cells demonstrates a regulatory effect of AMPK on hPepT1, along with an influence on both the microvilli and tight junction structures. The absence of an associated reduction in transepithelial peptide movement implies an additional stimulatory effect of AICAR on the basolateral peptide transport system in these cells. These results provide a link between the hPepT1 transporter and the metabolic state of this model enterocyte.

scholarly journals Glucose Transport in Isolated Brush Border Membrane from Rat Small Intestine

1973 ◽  
Vol 248 (1) ◽  
pp. 25-32
Author(s):  
Ulrich Hopfer ◽  
Kristine Nelson ◽  
Joseph Perrotto ◽  
Kurt J. Isselbacher
Keyword(s):  
Small Intestine ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Rat Small Intestine

Age-related changes in sodium-dependent glucose transport in rat small intestine

1986 ◽  
Vol 251 (2) ◽  
pp. G208-G217 ◽  
Author(s):  
H. J. Freeman ◽  
G. A. Quamme
Keyword(s):  
Small Intestine ◽  
Glucose Transport ◽  
Brush Border ◽  
Brush Border Membrane ◽  
High Capacity ◽  
Membrane Vesicles ◽  
Distal Segment ◽  
Brush Border Membrane Vesicles ◽  
Transport Systems ◽  
Sodium Dependent

Brush-border membrane vesicles were purified from jejunoileal segments of rats ranging from 3 to 156 wk. The kinetics of sodium-dependent glucose cotransport were studied under voltage-clamped, zero trans conditions over a wide range of cis-glucose concentrations (0.005-1.5 mM). Initial glucose uptake in brush-border membrane vesicles isolated from the proximal intestinal segment (50 cm from ligament of Treitz) of rats less than 7-8 wk of age demonstrated a distinct curvilinear Hofstee plot consistent with multiple-transport mechanisms. One system possessed an apparent Vmax of 10.6 +/- 0.5 nmol X mg prot-1 X min-1 and Km of 630 +/- 18 microM. The second system was characterized by Vmax of 0.9 +/- 0.1 nmol X mg prot-1 X min-1 and Km of 12 +/- 1 microM. In contrast, the distal segment (50 cm to end of small intestine) possessed only one sodium-dependent glucose carrier system. The apparent Vmax and Km were 1.11 +/- 0.20 nmol X mg protein-1 X min-1 and 49 +/- 7 microM, respectively. Sodium-activation curves in the presence of 0.3 and 0.03 mM glucose were consistent with more than one sodium ion with both systems. In contrast, rats 12-13 wk old and older possessed both sodium-dependent transport systems in the proximal early and distal small intestine. The high-capacity system is more abundant in the proximal than the distal segment. These data suggest that, under these specific conditions, there are two sodium-dependent glucose carriers in the intestine of young rats: one located in the jejunum characterized by high capacity and low affinity, and the second located throughout the jejunoileum characterized by low capacity and high affinity. Furthermore with age there is a development of the low-affinity system in the distal segments so that both systems are found along the length of the jejunum and ileum. Accordingly, serial and parallel heterogeneity of sodium-dependent glucose transport exists along the small intestine.

Unraveling the Inhibition of Intestinal Glucose Transport by Dietary Phenolics: A Review

2019 ◽  
Vol 25 (32) ◽  
pp. 3418-3433 ◽  
Author(s):  
Joana Pico ◽  
Mario M. Martínez
Keyword(s):  
Glucose Transport ◽  
Brush Border ◽  
Glucose Concentration ◽  
Metabolic Regulation ◽  
Brush Border Membrane ◽  
Glucose Transporter ◽  
Basolateral Membrane ◽  
Glucose Transporters ◽  
Flavonoid Glycosides ◽  
Glucose Response

Background: Glucose transport across the intestinal brush border membrane plays a key role in metabolic regulation. Depending on the luminal glucose concentration, glucose is mainly transported by the sodium- dependent glucose transporter (SGLT1) and the facilitated-transporter glucose transporter (GLUT2). SGLT1 is apical membrane-constitutive and it is active at a low luminal glucose concentration, while at concentrations higher than 50 mM, glucose is mainly transported by GLUT2 (recruited from the basolateral membrane). Dietary phenolic compounds can modulate glucose homeostasis by decreasing the postprandial glucose response through the inhibition of SGLT1 and GLUT2. Methods: Phenolic inhibition of intestinal glucose transport has been examined using brush border membrane vesicles from rats, pigs or rabbits, Xenopus oocytes and more recently Caco-2 cells, which are the most promising for harmonizing in vitro experiments. Results: Phenolic concentrations above 100 µM has been proved to successfully inhibit the glucose transport. Generally, the aglycones quercetin, myricetin, fisetin or apigenin have been reported to strongly inhibit GLUT2, while quercetin-3-O-glycoside has been demonstrated to be more effective in SGLT1. Additionally, epigallocatechin as well as epicatechin and epigallocatechin gallates were observed to be inhibited on both SGLT1 and GLUT2. Conclusion: Although, valuable information regarding the phenolic glucose transport inhibition is known, however, there are some disagreements about which flavonoid glycosides and aglycones exert significant inhibition, and also the inhibition of phenolic acids remains unclear. This review aims to collect, compare and discuss the available information and controversies about the phenolic inhibition of glucose transporters. A detailed discussion on the physicochemical mechanisms involved in phenolics-glucose transporters interactions is also included.

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