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

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.

scholarly journals Characterization of a sodium-dependent concentrative nucleobase-transport system in guinea-pig kidney cortex brush-border membrane vesicles

1994 ◽  
Vol 303 (3) ◽  
pp. 901-905 ◽  
Author(s):  
D A Griffith ◽  
S M Jarvis
Keyword(s):  
Guinea Pig ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Hill Coefficient ◽  
Kidney Cortex ◽  
Pig Kidney ◽  
Na Ions

The characteristics of hypoxanthine transport were examined in purified brush-border membrane vesicles isolated from guinea-pig kidney. Hypoxanthine uptake in the vesicles was specifically stimulated by both Na+ and an inside-negative potential, resulting in a transient accumulation of intravesicular hypoxanthine. Na(+)-dependent hypoxanthine influx was saturable (apparent Km 4.4 +/- 2.1 microM, Vmax. 128 +/- 29 pmol/min per mg of protein at 100 mM NaCl and 22 degrees C). Guanine, thymine, 5-fluorouracil and uracil inhibited hypoxanthine uptake (Ki values 1-30 microM), but adenine and the nucleosides inosine and thymidine were without effect. Guanine competitively inhibited Na(+)-dependent hypoxanthine influx, suggesting that it was a substrate for the active nucleobase transporter in guinea-pig renal membrane vesicles. A sigmoidal dependence between hypoxanthine influx and Na+ concentration was obtained (KNa 13 +/- 2 mM; Hill coefficient, h, 2.13 +/- 0.14), suggesting that at least two Na+ ions are transported per hypoxanthine molecule. This system differs from the Na(+)-nucleobase carrier in cultured LLC-PK1 renal cells, which has a stoichiometric coupling ratio of 1:1. These results represent the first demonstration of an active electrogenic nucleobase carrier in renal apical membrane vesicles.

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

scholarly journals Alterations in the mucosal processing of iron in response to very-short-term dietary iron depletion and repletion

1992 ◽  
Vol 284 (3) ◽  
pp. 877-884 ◽  
Author(s):  
R W Topham ◽  
C E Eads ◽  
B F Butler
Keyword(s):  
Brush Border ◽  
Iron Uptake ◽  
Brush Border Membrane ◽  
Control Diet ◽  
Membrane Vesicles ◽  
Test Dose ◽  
Brush Border Membrane Vesicles ◽  
Dietary Iron ◽  
Short Term ◽  
Iron Deficient

The transfer of control rats to a low-iron diet for only 24 h resulted in a 2-fold increase in iron uptake by brush-border membrane vesicles. Extension of the low-iron feeding period to 72 h or 2 weeks resulted in only small additional increases in iron uptake by vesicle preparations. In contrast, the transfer of iron-deficient rats to a control diet resulted in a progressive decrease in iron uptake by vesicles that reached a level equivalent to that of control rats in 2 weeks. 59Fe labelling of detergent extracts of these vesicle preparations provided evidence for the presence of an iron-binding protein composed of subunits of 52,000 Da. The changes in the 59Fe labelling of this protein component were consistent with the changes observed in iron uptake by intact brush-border membrane vesicles. The 59Fe-labelling profiles of mucosal ferritin and transferrin from a test dose also were changed substantially in response to very-short-term alterations in dietary iron. Even though changes in dietary iron rapidly altered iron uptake by brush-border membrane vesicles and the incorporation of 59Fe from the test dose into mucosal transferrin, changes in the incorporation of 59Fe into mucosal ferritin best reflected the actual changes in the transfer of iron from dose to plasma.

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