Development of nutrient transport systems in chick jejunum

1984 ◽  
Vol 246 (2) ◽  
pp. G101-G107 ◽  
Author(s):  
A. T. Shehata ◽  
J. Lerner ◽  
D. S. Miller
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Nutrient Transport ◽  
Membrane Vesicles ◽  
Developmental Time ◽  
Weight Basis ◽  
Transport Systems ◽  
Beta Alanine ◽  
Sodium Gradient ◽  
Wet Weight

Glutamate, beta-alanine, choline, and myoinositol transport was characterized in jejunal slices and brush-border membrane vesicles from 2- and 21-day chicks. Carrier-mediated, i.e., competitor-inhibitable, transport in slices (wet weight basis) and vesicles (protein basis) declined with age for the two amino acids but increased with age for myo-inositol; transport of choline did not change. These findings, along with previous data for the hexose system, cannot be explained solely by nonspecific changes in brush-border membrane architecture or permeability or by changes in the electrochemical sodium gradient that drives cotransport. They indicate that each specific brush-border membrane transport mechanism follows separate developmental time tables.

D-glucose and L-leucine transport by human intestinal brush-border membrane vesicles

1989 ◽  
Vol 256 (3) ◽  
pp. G618-G623 ◽  
Author(s):  
J. M. Harig ◽  
J. A. Barry ◽  
V. M. Rajendran ◽  
K. H. Soergel ◽  
K. Ramaswamy
Keyword(s):  
Small Intestine ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Transport Systems ◽  
Intestinal Brush Border Membrane ◽  
High Affinity ◽  
Intestinal Brush Border ◽  
Sodium Gradient

This study utilized intestinal brush-border membrane vesicles obtained from organ donor intestine to characterize the absorption of D-glucose and L-leucine in the human intestine. Both D-glucose and L-leucine were taken up by sodium gradient-dependent active transport along the entire length of the small intestine. The relative magnitude of transport for both substrates under sodium gradient conditions followed the order distal jejunum greater than proximal jejunum greater than distal ileum. The number of carrier systems in these brush-border membrane vesicles was estimated by Eadie-Hofstee plot analysis. This analysis revealed that L-leucine was actively transported via a single high-affinity transport system for the length of the human small intestine. In contrast, the transport of D-glucose occurred via a high-affinity system along the length of the intestine and via a low-affinity, high-flux transport system that was limited to the proximal intestine. Both glucose transport systems were sodium dependent and phlorizin sensitive. The locations and apparent kinetic parameters of these transport systems indicated that these systems function efficiently in vivo as important mechanisms for carbohydrate and protein assimilation in humans. The presence of these active transport systems along the entire small intestine explains the formidable capacity for carbohydrate and protein assimilation in humans.

Transport characteristics of renal brush border Na(+)- and K(+)-dependent uridine carriers

1990 ◽  
Vol 258 (5) ◽  
pp. F1203-F1210 ◽  
Author(s):  
C. W. Lee ◽  
C. I. Cheeseman ◽  
S. M. Jarvis
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Positive Charge ◽  
Membrane Vesicles ◽  
Transport Processes ◽  
Transport Systems ◽  
Uridine Uptake ◽  
Renal Brush Border Membrane ◽  
Coupling Stoichiometry ◽  
Renal Brush Border

The uptake of uridine into rat renal brush-border membrane vesicles is mediated by Na(+)- and K(+)-dependent concentrative transport processes. At a 100 mM extravesicular cation concentration the apparent Km values were 9.7 +/- 4.2 and 28 +/- 5 microM, and Vmax values were 28 +/- 4 and 7 +/- 1 pmol.mg protein-1.s-1 for the Na(+)- and K(+)-dependent systems, respectively. Uracil, D-ribose, and D-glucose failed to inhibit the uptake processes, indicating that these carriers are specific for nucleosides. Other purines and pyrimidines inhibited uridine uptake competitively, although these two transport systems seem to favor adenosine and pyrimidines as permeants. Evidence is also given that transport is rheogenic, involving a net transfer of positive charge. The Na+:uridine and K+:uridine coupling stoichiometry was found to be 1:1 and 3:2, respectively. Both systems can also be driven by an anion gradient with apparent NO3- affinity (KNO3-) values of 42 +/- 13 and 163 +/- 54 mM for Na(+)- and K(+)-dependent systems, respectively.

Uphill transport of beta-alanine in intestinal brush-border membrane vesicles

1990 ◽  
Vol 259 (3) ◽  
pp. G372-G379 ◽  
Author(s):  
Y. Miyamoto ◽  
H. Nakamura ◽  
T. Hoshi ◽  
V. Ganapathy ◽  
F. H. Leibach
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Beta Alanine ◽  
Intestinal Brush Border Membrane ◽  
High Affinity ◽  
Intestinal Brush Border ◽  
Proximal Small Intestine ◽  
Uptake Process

The characteristics of beta-alaline uptake were studied in brush-border membrane vesicles isolated from the proximal small intestine of rabbits and were compared with those of L-alpha-alanine uptake. The uptake of beta-alanine as well as L-alpha-alanine was significantly stimulated by imposing an inwardly directed Na+ gradient. Studies on transstimulation and substrate specificity provide evidence that the transport system serving beta-alanine is distinct from the system serving alpha-alanine. The beta-system also accepts taurine as a substrate. The Na(+)-dependent uptakes of beta-alanine and L-alpha-alanine were differentially influenced by anions. The order in which anions supported uptake was Cl- = SCN- greater than F- greater than NO3- = SO2(-4) for beta-alanine, whereas it was SCN- greater than F- = Cl- = NO3- greater than SO2(-4) for L-alpha-alanine. Cl- appeared to be the preferred anion to support the uptake of beta-alanine. beta-Alanine uptake was greater in the presence of an inwardly directed Cl- gradient than in the presence of Cl- at equal concentrations on both sides of the membrane. The uptake was maximal when a Na+ gradient and a Cl- gradient were present simultaneously. The NaCl gradient-driven beta-alanine uptake was stimulated by an inside-negative K(+)-diffusion potential induced by valinomycin, showing that the uptake process is electrogenic. Stoichiometric analyses suggest that multiple Na+ and one Cl- are associated with the uptake of one beta-alanine molecule. The kinetic study shows that the transporter for beta-alanine is a high-affinity, low-capacity system (Kt = 46 +/- 1 microM; Vmax = 30 +/- 1 pmol.mg protein-1.15 s-1).

Indirect coupling of urate and p-aminohippurate transport to sodium in human brush-border membrane vesicles

1996 ◽  
Vol 270 (1) ◽  
pp. F61-F68 ◽  
Author(s):  
F. Roch-Ramel ◽  
B. Guisan ◽  
L. Schild
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Indirect Coupling ◽  
Sodium Gradient ◽  
Beta Hydroxybutyrate ◽  
Sodium Cotransport ◽  
Stimulation Of

[14C]urate and p-[14C]aminohippurate (PAH) uptake by human brush-border membrane vesicles (BBMV) were measured in the presence of an inwardly oriented sodium gradient. No direct sodium cotransport was observed. Indirect [14C]urate coupling to sodium transport was demonstrated by cis-stimulation of [14C]urate with nicotinate or pyrazinoate (PZA) in the extravesicular medium but not by adding lactate, alpha-ketoglutarate, or beta-hydroxybutyrate. Indirect sodium coupling of [14C]PAH uptake was observed only when alpha-ketoglutarate was added to the extravesicular medium, a mechanism similar to that of basolateral membranes. The ability for PZA (and nicotinate) to cis-stimulate urate uptake was correlated with a high apparent affinity for the urate/anion exchanger. In urate-loaded vesicles, for identical medium concentrations, [14C]PZA uptake via the urateanion exchanger was 10 times higher than [14C]lactate uptake. Such high PZA affinity for the urate exchanger, working in parallel with PZA sodium cotransport can account for the stimulation of urate reabsorption by PZA in vivo.

scholarly journals Cystine uptake by rat renal brush-border vesicles

1981 ◽  
Vol 194 (2) ◽  
pp. 443-449 ◽  
Author(s):  
P D McNamara ◽  
L M Pepe ◽  
S Segal
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Early Time ◽  
Membrane Vesicles ◽  
Time Dependent ◽  
Transport Systems ◽  
Cortical Tissue ◽  
High Affinity ◽  
Renal Cortical Tissue ◽  
Renal Brush Border

Uptake of L-cystine by brush-border membrane vesicles isolated from rat renal-cortical tissue was time-dependent and occurred in the absence of cystine reduction. A significant capacity for vesicular binding of cystine was observed. The amount bound increased with time of incubation and could be displaced by thiol reagents. At early time points, cystine uptake measured the transport of cystine into the intravesicular space. Total cystine uptake was mediated by multiple transport systems, including a low-Km high-affinity component which was shared by lysine, arginine, ornithine and glutamine and on which hetero-exchange diffusion of lysine and cystine was demonstrated.

Potential-dependent D-glucose uptake by renal brush border membrane vesicles in the absence of sodium

1982 ◽  
Vol 242 (4) ◽  
pp. F340-F345
Author(s):  
S. Hilden ◽  
B. Sacktor
Keyword(s):  
Membrane Potential ◽  
Glucose Uptake ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Transport Systems ◽  
Uptake System ◽  
Renal Brush Border Membrane ◽  
Renal Brush Border

The uptake of D-glucose by renal brush border membrane vesicles was studied in the absence of Na+. Uptake of the sugar was membrane potential dependent (inside negative), inhibited by phlorizin, sugar and stereospecific, accelerated by exchange diffusion, saturable, and temperature dependent. The binding of phlorizin in the absence of Na+ was also increased by a membrane potential (inside negative). Thus, the properties of this membrane potential-dependent, Na+-independent sugar transport system resembled those described for the Na+-D-glucose cotransport system. In the absence of Na+ but in the presence of a valinomycin-induced K+ diffusion potential the apparent Km for D-glucose was 43 mM. This contrasted with an apparent Km of 1.8 mM for the Na+ chemical gradient system. Therefore, the Na+-independent uptake system represented a low-affinity transport mechanism. It is suggested that the same carrier mediated the Na+-independent and Na+-dependent transport systems. A hypothetical model for the membrane potential-dependent stimulation of D-glucose uptake in the absence of Na+ is proposed.

Multiple transport systems for organic cations in renal brush-border membrane vesicles

1989 ◽  
Vol 256 (4) ◽  
pp. F540-F548 ◽  
Author(s):  
Y. Miyamoto ◽  
C. Tiruppathi ◽  
V. Ganapathy ◽  
F. H. Leibach
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Diffusion Potential ◽  
Transport Systems ◽  
Organic Cations ◽  
Uptake Kinetic ◽  
Carrier Systems ◽  
Renal Brush Border

The characteristics of guanidine uptake in brush-border membrane vesicles isolated from rabbit renal cortex were investigated. Guanidine uptake was markedly stimulated by an outwardly directed H+ gradient, resulting in a transient uphill transport. This stimulation was not due to an inside-negative, H+-diffusion potential because an ionophore-induced H+-diffusion potential and a K+-diffusion potential (both inside-negative) failed to enhance guanidine uptake. The H+ gradient itself appeared to be the driving force for the uptake. These data suggest that guanidine-H+ antiport (or guanidine-OH- symport) is the mechanism of guanidine uptake in these membrane vesicles. Guanidine uptake was only minimally inhibited by organic cations such as tetraethylammonium, N1-methylnicotinamide, and choline, but many other organic cations such as amiloride, clonidine, imipramine, and harmaline caused considerable inhibition. Uptake of radiolabeled guanidine was inhibited more effectively by guanidine than by tetraethylammonium, whereas uptake of radiolabeled tetraethylammonium was inhibited more effectively by tetraethylammonium than by guanidine. beta-Lactam antibiotics did not inhibit guanidine uptake but did inhibit tetraethylammonium uptake. Kinetic analysis showed that there were at least two kinetically distinct carrier systems for guanidine uptake, whereas tetraethylammonium uptake occurred via a single carrier system. These data provide evidence that renal brush-border membranes possess multiple carrier systems for organic cations.

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