Intestinal absorption of ester and ether glycerophospholipids in guinea pig. Role of a phospholipase A2 from brush border membrane

Lipids ◽  
1987 ◽  
Vol 22 (1) ◽  
pp. 33-40 ◽  
Author(s):  
A. Diagne ◽  
S. Mitjavila ◽  
J. Fauvel ◽  
H. Chap ◽  
L. Douste-Blazy
Keyword(s):  
Guinea Pig ◽  
Phospholipase A2 ◽  
Intestinal Absorption ◽  
Brush Border ◽  
Brush Border Membrane

Effect of luminal angiotensin II on proximal tubule fluid transport: role of apical phospholipase A2

1994 ◽  
Vol 266 (2) ◽  
pp. F202-F209 ◽  
Author(s):  
L. Li ◽  
Y. P. Wang ◽  
A. W. Capparelli ◽  
O. D. Jo ◽  
N. Yanagawa
Keyword(s):  
Angiotensin Ii ◽  
Phospholipase A2 ◽  
Proximal Tubule ◽  
Brush Border ◽  
Fluid Transport ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Ang Ii ◽  
Potent Effect

Recent micropuncture studies showed the existence of high concentrations of angiotensin II (ANG II) in proximal tubular fluid. In the present study, we have examined the effect of luminal ANG II, alone and in combination with peritubular ANG II, on fluid transport (JV) in the isolated perfused rabbit proximal convoluted tubule. In comparison with peritubular ANG II, luminal ANG II caused a similar but more potent biphasic effect on JV. At 10(-11) M, luminal ANG II maximally increased JV to 204 +/- 22% of the baseline compared with 142 +/- 10% by peritubular ANG II at 10(-10) M. At 10(-8) M, luminal ANG II suppressed JV to 9.7 +/- 16% of the baseline compared with 64 +/- 14% by peritubular ANG II. When luminal and peritubular ANG II were combined at concentrations that impose similar effect on JV, the effects of luminal and peritubular ANG II were not additive. However, when combined at concentrations that would otherwise impose opposing effects on JV, the stimulatory effect predominated. In support of the role of apical phospholipase A2 (PLA2) on the effect of luminal ANG II, ANG II stimulated PLA2 activity in isolated brush-border membrane vesicles, and addition of PLA2 inhibitor, mepacrine or dibucaine, to the luminal perfusate attenuated the effect of luminal ANG II on JV. In summary, these studies show a potent effect of luminal ANG II on proximal tubule JV involving activation of brush-border membrane PLA2. When combined, luminal and peritubular ANG II exert their effects in concert on proximal tubule JV.

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.

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.

Theoretical and experimental discrimination between Cl(-)-H+ symporters and Cl-/OH- antiporters

1996 ◽  
Vol 271 (5) ◽  
pp. C1612-C1628 ◽  
Author(s):  
F. Alvarado ◽  
M. Vasseur
Keyword(s):  
Guinea Pig ◽  
Gene Family ◽  
Brush Border ◽  
Anion Exchanger ◽  
Kinetic Models ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Mobile Carrier ◽  
Ph Dependent ◽  
Functionally Diverse

A Cl(-)-H+ symport and a Cl-/OH- antiport cannot be readily distinguished physicochemically, but a kinetic distinction is theoretically possible, because a Cl(-)-H+ symporter involves a two-site carrier whereas a Cl-/OH- antiporter involves a single-site carrier. Accordingly, we have developed kinetic models and equations that we have tested by studying Cl- uptake by isolated guinea pig ileal brush-border membrane vesicles as a function of Cl- or H+ concentration. We conclude that a two-site Cl(-)-H+ symporter with a 1:1 stoichiometry explains the pH-dependent Cl- uptake and Cl-/Cl- exchange activities of the brush-border membrane in terms of a single random nonobligatory mobile carrier where exchange occurs by counterflow. This symport, probably involving an anion exchanger (AE 2) protein, differs, therefore, functionally from the erythrocyte's band 3 AE1, which involves an antiport. The question is whether members of the AE gene family can be functionally diverse, even when their primary structures exhibit up to 50% overall homologies.

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

Ontogeny of Iron Uptake across Brush Border Membrane of Guinea Pig Duodenum and Its Autoradiographic Localisation

Neonatology ◽  
1991 ◽  
Vol 59 (1) ◽  
pp. 30-36 ◽  
Author(s):  
Edward S. Debnam ◽  
Surit K.S. Srai ◽  
George Chowrimootoo ◽  
Owen Epstein
Keyword(s):  
Guinea Pig ◽  
Brush Border ◽  
Iron Uptake ◽  
Brush Border Membrane

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.

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