Characterization and chemical modification of the Na+-dependent bile-acid transport system in brush-border membrane vesicles from rabbit ileum

1992 ◽  
Vol 1111 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Werner Kramer ◽  
Sven-Boris Nicol ◽  
Frank Girbig ◽  
Ulrike Gutjahr ◽  
Simone Kowalewski ◽  
...  
Keyword(s):  
Bile Acid ◽  
Chemical Modification ◽  
Transport System ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Acid Transport ◽  
Rabbit Ileum ◽  
Bile Acid Transport

Ontogeny of bile acid transport in brush border membrane vesicles from rat ileum

1986 ◽  
Vol 90 (5) ◽  
pp. 1188-1196 ◽  
Author(s):  
M.Susan Moyer ◽  
James E. Heubi ◽  
Anita L. Goodrich ◽  
William F. Balistreri ◽  
Frederick J. Suchy
Keyword(s):  
Bile Acid ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Acid Transport ◽  
Rat Ileum ◽  
Bile Acid Transport

Effect of pH on phosphate transport in rat renal brush border membrane vesicles

1985 ◽  
Vol 248 (5) ◽  
pp. F705-F710 ◽  
Author(s):  
M. Amstutz ◽  
M. Mohrmann ◽  
P. Gmaj ◽  
H. Murer
Keyword(s):  
Transport System ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Phosphate Uptake ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Effect Of Ph ◽  
High Sodium ◽  
Renal Brush Border Membrane ◽  
Renal Brush Border

The initial linear rate of phosphate uptake was analyzed in rat renal brush border membrane vesicles. An increase in medium pH from 6.0 to 8.0 increased the sodium gradient-dependent phosphate uptake about 20-fold. Sodium-independent phosphate uptake was not altered in this pH range. At pH 7.4 an intravesicular acid pH stimulated the initial linear uptake rate (20-25%). The apparent Km for sodium increased from about 100 to 200 mM when pH was decreased from 7.4 to 6.4. The Hill coefficient for sodium interaction was close to 2 and was unaffected by pH. Increasing external sodium reduced the apparent Km of the transport system for phosphate independent of pH. Variations of phosphate concentration had no influence on the apparent Km for sodium. At high sodium concentrations, small effects (20-30%) of pH on the apparent Vmax of the transport system were found; measured at saturating sodium concentrations, the apparent Km values calculated on the basis of total phosphate were increased (50-60%) when pH was decreased from 7.4 to 6.4. The data indicate that the major effect of pH is to modify the interaction of the transport system with sodium. At nonsaturating sodium concentrations, this resulted indirectly in a reduction in the affinity for phosphate related to a different occupancy of the sodium binding site. The differences of transport rate at low phosphate and high sodium concentrations could be explained by preferential transport of divalent phosphate as well as by pH effects on other carrier properties.

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