Resection of rabbit ileum: effect on brush border membrane enzyme markers and lipids

1985 ◽  
Vol 63 (12) ◽  
pp. 1528-1532 ◽  
Author(s):  
M. Keelan ◽  
K. Walker ◽  
A. B. R. Thomson
Keyword(s):  
Fatty Acids ◽  
Total Cholesterol ◽  
Bile Acids ◽  
Chain Length ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Composition ◽  
Rabbit Ileum ◽  
Ileal Resection ◽  
Distal Small Intestine

Alterations in transport function have been described 6 weeks after surgical resection of 50% of the distal small intestine. Previous studies demonstrated a modest increase in the jejunal uptake of medium chain length fatty acids following resection, while the uptake of many other lipids (cholesterol, bile acids, fatty alcohols, short and long chain length fatty acids) appears to be unaffected. Marked changes in the kinetic constants for the carrier-mediated uptake of four sugars and leucine were observed following resection, but the changes in transport were not associated with changes in the mucosal surface area. This study was undertaken to examine the possible adaptive mechanisms that occur with ileal resection in the rabbit. A 29% increase in the wet weight of jejunal mucosal scrapings and a 53% increase in jejunal brush border membrane (BBM) protein was observed following resection. The jejunal BBM sucrase (S) was unchanged following ileal resection, but alkaline phosphatase (AP) total activities were increased in the resected rabbits. This resulted in a 45% increase in the ratio of AP/S with resection. The lipid composition (total free fatty acids, total bile acids, total cholesterol, total phospholipids, individual phospholipids, and the ratio of total phospholipids/total cholesterol) of BBM was similar in control and resected rabbits. This suggests that quantitative rather than qualitative changes in the membrane composition may be responsible for the transport changes observed in resected animals.

Effects of taurodeoxycholate on in vivo water and solute transport in rat jejunum in absence and presence of calcium

1986 ◽  
Vol 250 (2) ◽  
pp. G248-G251
Author(s):  
H. V. Ammon ◽  
D. S. Cho ◽  
R. L. Loeffler ◽  
K. L. Reetz
Keyword(s):  
Fatty Acids ◽  
Bile Acids ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Calcium Absorption ◽  
Intestinal Transport ◽  
Fluid Secretion ◽  
Rat Jejunum ◽  
Perfusion Studies

Bile acids and fatty acids enhance the permeability of brush-border membrane vesicles for calcium. It has been postulated that increased influx of calcium into the enterocyte might be responsible for the fluid secretion induced by dihydroxy bile acids and fatty acids. During in vivo perfusion studies of the rat jejunum, 15 mM taurodeoxycholate induced secretion of electrolytes and water (P less than 0.001), reduced glucose absorption (P less than 0.001), and enhanced the absorption of mannitol (P less than 0.0125) and calcium (P less than 0.001). Calcium absorption continued to be enhanced during perfusion of a CaCl2-containing solution following the perfusion with taurodeoxycholate (P less than 0.05). In view of the previously demonstrated enhanced permeability of the apical brush-border membrane in the presence of bile acids, it is very likely that some calcium enters the enterocyte along the steep concentration gradient in the presence of taurodeoxycholate. In spite of enhanced calcium absorption, 15 mM CaCl2 had no effect on control absorption rates or on fluid secretion induced by taurodeoxycholate. The data indicate that the effects of bile acids on intestinal transport are not mediated by an influx of calcium into the enterocyte.

The aging gut

1986 ◽  
Vol 64 (1) ◽  
pp. 30-38 ◽  
Author(s):  
A. B. R. Thomson ◽  
M. Keelan
Keyword(s):  
Fatty Acids ◽  
Gastrointestinal Tract ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Physiological Function ◽  
Normal Function ◽  
Membrane Composition ◽  
Form And Function ◽  
Age Related ◽  
And Function

A spectrum of changes occurs in the function of the gastrointestinal tract throughout the life of the animal. With aging, there is a decline towards newborn levels of the villus surface area and brush border membrane markers, but the absorption of some nutrients continues to increase (such as glucose and vitamin), whereas the absorption of some nutrients falls (such as cholesterol and fatty acids). Clearly there is a distinction between age-related alterations in intestinal form and function, and some of the enzyme- or carrier-mediated changes are substrate specific. With aging, the structure and brush border membrane composition of the intestine tends to regress towards newborn levels. It remains to be clarified whether these changes are a benefit to the animal, whether they represent a degeneration of normal function, and whether these changes are the cause or the effect of various age-related alterations in metabolic and physiological function.

Transepithelial transport of cholyltaurine by Caco-2 cell monolayers is sodium dependent

1993 ◽  
Vol 264 (6) ◽  
pp. G1118-G1125 ◽  
Author(s):  
C. E. Chandler ◽  
L. M. Zaccaro ◽  
J. B. Moberly
Keyword(s):  
Bile Acids ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Incubation Temperature ◽  
Membrane Vesicles ◽  
Metabolic Inhibitors ◽  
Intestinal Lumen ◽  
Transepithelial Transport ◽  
Reverse Direction ◽  
Dependent Transport

Bile acids are efficiently recovered from the intestinal lumen by a Na(+)-dependent transport process that is localized in the ileal enterocyte brush-border membrane. To establish a cell culture model for this process, we examined the Na+ dependence of cholyltaurine (C-tau; taurocholate) transport across monolayers of differentiated Caco-2 cells grown on permeable filter inserts. Transport of [3H]C-tau was Na+ dependent (> 20-fold stimulation), saturable, and time linear for at least 60 min. The apparent Michaelis constant of [3H]C-tau transport was approximately 65 microM, and the maximal transport rate was approximately 800 pmol.min-1.mg protein-1. Transport of [3H]C-tau in the apical-to-basolateral direction was 17-fold greater than transport in the reverse direction. Lowered incubation temperature, various metabolic inhibitors, and various unlabeled bile acids inhibited [3H]C-tau transport. Caco-2 cells thus transport bile acids in a manner similar to that described for ileal brush-border membrane vesicles and isolated ileal enterocytes and are therefore an appropriate model for studying the molecular basis of ileal bile acid transport.

cDNA cloning and localization of a band 3-related protein from ileum

1992 ◽  
Vol 263 (3) ◽  
pp. G345-G352 ◽  
Author(s):  
A. Chow ◽  
J. W. Dobbins ◽  
P. S. Aronson ◽  
P. Igarashi
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Band 3 ◽  
Related Protein ◽  
Rabbit Ileum ◽  
Molecular Identity ◽  
Polymerase Chain ◽  
Related Proteins

A Cl(-)-HCO3- exchanger in the brush-border membrane mediates active Cl- absorption and regulates intracellular pH in rabbit ileum. The molecular identity of the ileal Cl(-)-HCO3- exchanger has not been established. The best-characterized plasma membrane Cl(-)-HCO3- exchanger is erythroid band 3. Structurally related proteins in nonerythroid tissues comprise an anion exchanger (AE) family. We used the polymerase chain reaction to amplify and clone a cDNA encoding an ileal band 3-related protein (B3RP) from rabbit ileal enterocytes. The composite sequence is 3,909 bp and is predicted to encode a protein of 136 kDa. The deduced amino acid sequence is 95% identical to murine renal AE2, indicating that ileal B3RP is rabbit AE2. Antisera generated against a cytoplasmic fragment of ileal B3RP recognized a 160- to 170-kDa polypeptide in the brush-border membrane, but not the basolateral membrane, of ileal crypt and villus enterocytes. This correlates with previous studies indicating that a Cl(-)-HCO3- exchange is present in brush-border but not basolateral membrane vesicles from rabbit ileal enterocytes. We conclude that ileal B3RP is a product of the AE gene family, and is present in the brush-border of ileal enterocytes, where it may mediate Cl(-)-HCO3- exchange.

Effects of cations on pH gradient-stimulated sulfate transport in rabbit ileal brush-border membrane vesicles

1985 ◽  
Vol 249 (5) ◽  
pp. G614-G621 ◽  
Author(s):  
C. M. Schron ◽  
R. G. Knickelbein ◽  
P. S. Aronson ◽  
J. Della Puca ◽  
J. W. Dobbins
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Disodium Salt ◽  
Brush Border Membrane Vesicles ◽  
Ph Gradient ◽  
Disulfonic Acid ◽  
Rabbit Ileum ◽  
External K

In brush-border membrane vesicles from rabbit ileum, we previously reported pH gradient-stimulated SO4 uptake and presented evidence that this represents carrier-mediated SO4-OH exchange. In the present study inhibitors of SO4-OH exchange (H-SO4 cotransport) were shown not to inhibit Na-SO4 cotransport, suggesting that these are two separate carrier-mediated transport mechanisms. While pH gradient-stimulated SO4 uptake was inhibited 87% by 0.1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, disodium salt (DIDS) and 79% by 1.0 mM furosemide, Na+-stimulated SO4 uptake was only inhibited 11 and 0%, respectively. K+ (20 mM), Cl (5 mM), and oxalate (0.25 mM) inhibited pH gradient-stimulated SO4 uptake (38-65%) but had no effect on Na+-stimulated SO4 uptake. Finally, at Na+ concentrations (10 mM) significantly less than that required for Na+-stimulated SO4 uptake (60-100 mM), external Na+ inhibited pH gradient-stimulated SO4 uptake, suggesting two independent effects of this cation. SO4 uptake was also inhibited by external K+ both in the presence and absence of a pH gradient. A Dixon plot of the DIDS-sensitive SO4 uptake under pH gradient conditions yielded a straight line, indicating a single site of interaction between external K+ and the SO4-OH carrier (apparent Ki = 7.2 mM). In contrast to the inhibition by external K+, internal K+ stimulated SO4 uptake. This effect was DIDS sensitive and not enhanced by valinomycin, suggesting an interaction of internal K+ with the SO4-OH exchanger independent of a K+-induced electrical potential. SO4 uptake and the effects of K+ were pH modulated with less SO4 uptake and less K+ effect at higher pH.(ABSTRACT TRUNCATED AT 250 WORDS)

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