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.

Expression of Na+-d-glucose cotransporter in brush-border membrane of the chicken intestine

1999 ◽  
Vol 276 (2) ◽  
pp. R627-R631 ◽  
Author(s):  
Carles Garriga ◽  
Nativitat Rovira ◽  
Miquel Moretó ◽  
Joana M. Planas
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Western Blot ◽  
Brush Border ◽  
Synthetic Peptide ◽  
Brush Border Membrane ◽  
Polyclonal Antibodies ◽  
Membrane Vesicles ◽  
Dependent Transport

We have studied the expression of Na+-d-glucose cotransporter in brush-border membrane vesicles (BBMVs) of chicken enterocytes to correlate the changes in the apical Na+-dependent transport with the changes in the amounts of transporter determined by Western blot analysis. Two different rabbit polyclonal antibodies were used simultaneously. The antibody raised against amino acids 564–575 of the deduced amino acid sequence of rabbit intestinal SGLT-1 ( antibody 1) specifically detects a single 75-kDa band in the three segments, and this band disappeared when the antibody was preabsorbed with the antigenic peptide. The antibody raised against the synthetic peptide corresponding to amino acids 402–420 of the same protein ( antibody 2) only reacts with jejunal and ileal samples, but no signal is found in BBMVs of rectum. Only when antibody 1 was used was there a linear correlation between the maximal transport rates of hexoses in BBMVs and the relative protein amounts determined by Western blot. These results indicate that the Na+-d-glucose cotransport in the jejunum, the ileum, and the rectum of chickens is due to an SGLT-1 type protein.

A carrier-mediated, Na+ gradient-dependent transport for biotin in human intestinal brush-border membrane vesicles

1987 ◽  
Vol 253 (5) ◽  
pp. G631-G636 ◽  
Author(s):  
H. M. Said ◽  
R. Redha ◽  
W. Nylander
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicle ◽  
Electrical Potential ◽  
Membrane Vesicles ◽  
Intestinal Brush Border Membrane ◽  
Membrane Surfaces ◽  
Intestinal Brush Border ◽  
Cotransport System ◽  
Dependent Transport

Transport of biotin across human intestinal brush-border membrane (BBM) was examined using brush-border membrane vesicle (BBMV) technique. Uptake of biotin by BBMV is mostly the result of transport of the substrate into an active intravesicular space with little binding to membrane surfaces. The transport of biotin was carrier mediated and was 1) Na+ (but not K+) gradient dependent with a distinct "over-shoot" phenomenon, 2) saturable as a function of concentration in the presence of a Na+ (but not a K+) gradient with an apparent Km and Vmax for the Na+ gradient-dependent system of 5.26 microM and 13.47 pmol.mg protein-1.20 s-1, respectively, and 3) inhibited by structural analogues and related compounds. Unlike the electrogenic transport of D-glucose, transport of the anionic biotin in the presence of a Na+ gradient (out greater than in) was not affected by imposing a relatively positive intravesicular electrical potential, suggesting that biotin transport is most likely an electroneutral process. These results demonstrate the existence of a carrier-mediated system for biotin transport in human BBM and show that the transport process is Na+ gradient dependent and electrically silent. It is suggested that biotin transport across the BBM is driven by a Na+ gradient most probably through a biotin-Na+ cotransport system.

scholarly journals Membrane-Potential-Sensitive, Na+-Independent Lysine Transport by Lobster Hepatopancreatic Brush Border Membrane Vesicles

1987 ◽  
Vol 127 (1) ◽  
pp. 373-387
Author(s):  
GREGORY A. AHEARN ◽  
LAUREL P. CLAY
Keyword(s):  
Membrane Potential ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Acidic Ph ◽  
S Uptake ◽  
Apparent Diffusion ◽  
Leucine Transport ◽  
Dependent Transport

Transport of l-[3H]lysine by epithelial brush border membrane vesicles (BBMV) of lobster hepatopancreas, formed by a magnesium precipitation technique, was insensitive to transmembrane gradients of Na+, K+, TMA+ or H+. Apparent initial lysine entry rates (15 s uptake) and extent of amino acid accumulation against a concentration gradient (overshoot) were both stimulated by transmembrane anion gradients according to the following sequence: SCN− > Cl− > gluconate−. The magnitude of this anion-gradient-dependent transport was significantly increased by bilateral acidic pH. Lysine transport at acidic pH strongly responded to transmembrane potential developed by addition of valinomycin to K+-loaded vesicles, or was markedly reduced if K+-equilibrated vesicles were incubated with the ionophore in the presence of an inwardly directed SCN− gradient. Lysine influx occurred by the combination of at least one carrier process and ‘apparent diffusion’. l-Arginine, l-alanine and l-leucine, added to the external medium, were all strong inhibitors of lysine influx. The first two were competitive inhibitors of lysine entry, while the latter was non-competitive in effect. These results suggest that lysine, arginine and alanine may share a common, Na+-independent, membrane-potential-sensitive transport mechanism in lobster BBMV. Leucine transport may occur in these membranes by a separate agency.

myo-Inositol transport in renal brush border vesicles and it inhibition by D-glucose

1980 ◽  
Vol 239 (2) ◽  
pp. F113-F120 ◽  
Author(s):  
M. R. Hammerman ◽  
B. Sacktor ◽  
W. H. Daughaday
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Initial Rate ◽  
Membrane Vesicles ◽  
Electrochemical Gradient ◽  
Patients With Diabetes ◽  
Dependent Transport ◽  
The Relationship ◽  
Inositol Uptake ◽  
Renal Brush Border

We examined the mechanism of myo-inositol uptake by rabbit renal proximal tubule brush border membrane vesicles and characterized the relationship between the transports of myo-inositol and D-glucose. A 100 mM Na+ electrochemical gradient (extravesicular medium > intravesicular medium) stimulated the initial rate of myo-inositol uptake 20- to 60-fold. Other cation gradients were ineffective. The Na+ myo-inositol co-transport system was shown to be electrogenic. The Na+ electrochemical gradient-dependent uptake of myo-inositol saturated at about 1 mM myo-inositol, with an apparent Km of 94 micro M at an initial 100 mM Na+ gradient. D-Glucose was an inhibitor of the Na+ gradient-dependent uptake of myo-inositol. D-Glucose, but not L-glucose, elicited accelerative exchange diffusion of myo-inositol. myo-Inositol did not significantly inhibit the Na+ gradient-dependent transport of D-glucose. We suggest that D-glucose inhibits myo-inositol uptake by dissipating the membrane potential and sharing the myo-inositol carrier. The inhibition of myo-inositol transport across the brush border membrane by D-glucose explains how glycosuria could produce inosituria in patients with diabetes mellitus.

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