Role of brush border Na+/H+ exchange in canine ileal absorption

1996 ◽  
Vol 41 (4) ◽  
pp. 651-659 ◽  
Author(s):  
Michael M. Maher ◽  
Jacqueline D. Gontarek ◽  
Ramon E. Jimenez ◽  
Mark Donowitz ◽  
Charles J. Yeo
Keyword(s):  
Brush Border ◽  
Ileal Absorption

scholarly journals Functional coupling of the downregulated in adenoma Cl−/base exchanger DRA and the apical Na+/H+ exchangers NHE2 and NHE3

2009 ◽  
Vol 296 (2) ◽  
pp. G202-G210 ◽  
Author(s):  
Mark W. Musch ◽  
Donna L. Arvans ◽  
Gary D. Wu ◽  
Eugene B. Chang
Keyword(s):  
Carbonic Anhydrase ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Intestinal Epithelial Cells ◽  
Functional Coupling ◽  
Intestinal Epithelial ◽  
Colon Cells ◽  
Base Exchange ◽  
Synaptotagmin I

Non-nutrient-dependent salt absorption across the brush-border membrane of intestinal epithelial cells is primarily mediated by coupled apical Na+/H+ (aNHE) and anion exchange transport, with the latter suspected of being mediated by DRA (downregulated in adenoma; SLC26A3) that is defective in congenital chloridorrhea. To investigate DRA in greater detail and determine whether DRA and NHE activities can be coupled, we measured 22Na+ and 36Cl− uptake in Caco2BBE colon cells infected with the tet-off-inducible DRA transgene. Under basal conditions, DRA activity was low in normal and infected Caco2BBE cells in the presence of tetracycline, whereas NHE activities could be easily detected. When apical NHE activity was increased by transfection or serum-induced expression of the aNHE isoforms NHE2 and NHE3, increased 36Cl− uptake was observed. Inhibition of DRA activity by niflumic acid was greater than that by DIDS as well as by the NHE inhibitor dimethylamiloride and the carbonic anhydrase inhibitor methazolamide. DRA activity was largely aNHE-dependent, whereas a component of DRA-independent aNHE uptake continued to be observed. Coupled aNHE and DRA activities were inhibited by increased cellular cAMP and calcium and were associated with synaptotagmin I-dependent, clathrin-mediated endocytosis. In summary, these data support the role of DRA in electroneutral NaCl absorption involving functional coupling of Cl−/base exchange and apical NHE.

scholarly journals Role of NHE3 in Mediating Renal Brush Border Na+-H+Exchange

1996 ◽  
Vol 271 (51) ◽  
pp. 32749-32752 ◽  
Author(s):  
Ming-Shiou Wu ◽  
Daniel Biemesderfer ◽  
Gerhard Giebisch ◽  
Peter S. Aronson
Keyword(s):  
Brush Border ◽  
Renal Brush Border

Folate transport by human intestinal brush-border membrane vesicles

1987 ◽  
Vol 252 (2) ◽  
pp. G229-G236 ◽  
Author(s):  
H. M. Said ◽  
F. K. Ghishan ◽  
R. Redha
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Disulfonic Acid ◽  
Folate Transport ◽  
Intestinal Brush Border Membrane ◽  
Transport Carrier ◽  
Incubation Buffer

Transport of folic acid (Pte-Glu) across the brush-border membrane of human intestine was studied using brush-border membrane vesicle (BBMV) technique. The transport of Pte-Glu was higher in BBMV prepared from the jejunum than those prepared from the ileum (0.70 +/- 0.05 and 0.14 +/- 0.02 pmol X mg protein-1 X 10 s-1, respectively). The transport of Pte-Glu appeared to be carrier mediated and was pH dependent and increased with decreasing incubation buffer pH; saturable (Kt = 1.69 microM, Vmax = 4.72 pmol X mg protein-1 X 10 s-1); inhibited in a competitive manner by the structural analogues 5-methyltetrahydrofolate, methotrexate, and 5-formyltetrahydrofolate (Ki = 2.2, 1.4 and 1.4 microM, respectively); not affected by inducing a relatively positive or negative intravesicular compartment; independent of Na+ gradient; and inhibited by 4,4'-diisothiocyanatostlibene-2,2'-disulfonic acid (DIDS), an anion exchange inhibitor. The increase in Pte-Glu transport on decreasing incubation buffer pH appeared to be in part mediated through a direct effect of acidic pH on the transport carrier and in part through the pH gradient imposed by activating Pte-Glu-:OH- exchange and/or Pte-Glu-:H+ co-transport mechanisms. The important role of an acidic extravesicular environment in Pte-Glu transport is consistent with a role for the intestinal surface acid microclimate in folate transport. These results demonstrate that Pte-Glu transport in human BBMV occurs by a carrier-mediated system that is similar to that described for rat and rabbit intestinal BBMV.

Contribution of Renal Angiotensin Converting Enzyme(ACE) to Blood Pressure Regulation: Possible Role of Brush Border Ace

1987 ◽  
Vol 9 (2-3) ◽  
pp. 441-447 ◽  
Author(s):  
F. Ikemoto ◽  
S. Itoh ◽  
G. Song ◽  
M. Tanaka ◽  
T. Takada ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Converting Enzyme ◽  
Brush Border ◽  
Blood Pressure Regulation ◽  
Pressure Regulation ◽  
Converting Enzyme

Role of Alkaline Phosphatase in Phosphate Uptake into Brush Border Membrane Vesicles from Human Intestinal Mucosa

1985 ◽  
Vol 97 (5) ◽  
pp. 1461-1466 ◽  
Author(s):  
Kazuyuki HIRANO ◽  
Yuichi IIIZUMI ◽  
Yukio MORI ◽  
Kazumi TOYOSHI ◽  
Mamoru SUGIURA ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Intestinal Mucosa ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Phosphate Uptake ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles

Role of rat intestinal brush-border membrane angiotensin-converting enzyme in dietary protein digestion

1987 ◽  
Vol 253 (6) ◽  
pp. G781-G786 ◽  
Author(s):  
M. Yoshioka ◽  
R. H. Erickson ◽  
J. F. Woodley ◽  
R. Gulli ◽  
D. Guan ◽  
...  
Keyword(s):  
Amino Acids ◽  
Angiotensin Converting Enzyme ◽  
Brush Border ◽  
Dietary Protein ◽  
Brush Border Membrane ◽  
Biologically Active ◽  
Converting Enzyme ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border

The role of rat intestinal angiotensin-converting enzyme (ACE; E.C 3.4.15.1) in the digestion and absorption of dietary protein was investigated. Enzyme activity was associated with the brush-border membrane fraction, with the highest activity in the proximal to midregion of the small intestine. Preliminary enzyme characterization studies were carried out using purified brush-border membrane preparations. When a variety of N-blocked synthetic peptides were used as potential substrates for ACE, activity was highest with those containing proline at the carboxy terminal position. The hydrolytic rates observed with these prolyl peptides were comparable to those observed when major digestive peptidases of the brush-border membrane such as aminopeptidase N and dipeptidyl aminopeptidase IV were assayed. When isolated rat jejunum was perfused in vivo with solutions of Bz-Gly-Ala-Pro, the dipeptide Ala-Pro was the main hydrolytic product detected in the perfusates. Absorption rates of the constituent amino acids, alanine and proline, depended on the concentration of peptide perfused. Captopril, an active site specific ACE inhibitor, significantly inhibited hydrolysis and absorption of constituent amino acids from Bz-Gly-Ala-Pro. These results show that intestinal brush-border membrane ACE functions as a digestive peptidase in addition to its role as a regulator of biologically active peptides in other tissues.

Role of calcium and calmodulin in the regulation of the rabbit ileal brush-border membrane Na+/H+ antiporter

1989 ◽  
Vol 108 (3) ◽  
pp. 207-215 ◽  
Author(s):  
Eugene Emmer ◽  
Richard P. Rood ◽  
John H. Wesolek ◽  
Michael E. Cohen ◽  
R. Scott Braithwaite ◽  
...  
Keyword(s):  
Brush Border ◽  
Brush Border Membrane
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