scholarly journals Renal transport of neutral amino acids. Demonstration of Na+-independent and Na+-dependent electrogenic uptake of l-proline, hydroxy-l-proline and 5-oxo-l-proline by luminal-membrane vesicles

1984 ◽  
Vol 220 (1) ◽  
pp. 25-33 ◽  
Author(s):  
H Røigaard-Petersen ◽  
M I Sheikh
Keyword(s):  
Amino Acids ◽  
Renal Cortex ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Acid Transport ◽  
Physiological Importance ◽  
High Affinity ◽  
Luminal Membrane ◽  
Pars Recta ◽  
Pars Convoluta

Uptake of L-proline, hydroxy-L-proline and 5-oxo-L-proline by luminal-membrane vesicles isolated either from whole cortex or from pars convoluta or pars recta of proximal tubules was studied by a spectrophotometric method. Uptake of L-proline and hydroxy-L-proline by vesicles from whole cortex was mediated by both Na+-dependent and Na+-independent, but electrogenic, processes, whereas transport of 5-oxo-L-proline in these vesicles was strictly Na+-dependent. Eadie-Hofstee analysis of saturation-kinetic data suggested the presence of multiple transport systems in luminal-membrane vesicles from whole renal cortex for the uptake of all these amino acids. Tubular localization of the transport systems was studied by the use of vesicles derived from pars convoluta and from pars recta. In pars recta transport of all three amino acids was strictly dependent on Na+ and occurred via a high-affinity system (half-saturation: 0.1-0.3 mM). Cation-dependent but Na+-unspecific transport of low affinity for L-proline and hydroxy-L-proline was exclusively localized to the pars convoluta, which also contained a Na+-preferring system of intermediate affinity (half-saturation: L-proline, 0.75 mM; hydroxy-L-proline, 1.3 mM). 5-Oxo-L-proline was transported by low-affinity and Na+-dependent systems in both pars convoluta and pars recta. Competition experiments revealed that transport systems for L-proline and hydroxy-L-proline are common, but indicated separate high-affinity transport systems for 5-oxo-L-proline and L-proline in luminal-membrane vesicles from pars recta. The physiological importance of the presence of various neutral amino acid-transport systems in different segments of the proximal tubule is discussed.

scholarly journals Renal transport of neutral amino acids. Cation-dependent uptake of l-alanine by luminal-membrane vesicles

1987 ◽  
Vol 248 (2) ◽  
pp. 533-538 ◽  
Author(s):  
K E Jørgensen ◽  
M I Sheikh
Keyword(s):  
Transport System ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Physiological Importance ◽  
High Affinity ◽  
Luminal Membrane ◽  
Alanine Transport ◽  
Pars Recta ◽  
Pars Convoluta ◽  
Filtration Technique

The characteristics of L-alanine transport in luminal-membrane vesicles isolated either from whole cortex or from pars convoluta or pars recta of rabbit proximal tubules were studied by a rapid filtration technique and by a spectrophotometric method. Uptake of L-alanine by vesicles from whole cortex was mediated by both Na+-dependent and Na+-independent, but electrogenic, processes. The nature, mechanism and tubular localization of the transport systems were studied by the use of vesicles derived from pars convoluta and pars recta. In vesicles from pars recta transport of L-alanine was strictly dependent on Na+ and occurred via a dual transport system, namely a high-affinity (half-saturation 0.14 mM) and a low-affinity system (half-saturation 9.6 mM). The cation-dependent but Na+-unspecific transport system for L-alanine was exclusively localized to the pars convoluta, which also contained an Na+-preferring system of intermediate affinity (half saturation 2.1 mM). A closer examination of the mechanism of transport of L-alanine in vesicles from pars convoluta revealed that an H+ gradient (extravesicular greater than intravesicular) can drive the transport of L-alanine into the vesicles both in the presence and in the absence of Na+. The physiological importance of various L-alanine transporters is briefly discussed.

Proton gradient-dependent renal transport of glycine: evidence for vesicle studies

1990 ◽  
Vol 258 (2) ◽  
pp. F388-F396 ◽  
Author(s):  
H. Roigaard-Petersen ◽  
H. Jessen ◽  
S. Mollerup ◽  
K. E. Jorgensen ◽  
C. Jacobsen ◽  
...  
Keyword(s):  
Transport System ◽  
Membrane Vesicles ◽  
Proton Gradient ◽  
Transport Systems ◽  
Rabbit Kidney ◽  
Renal Transport ◽  
High Affinity ◽  
Luminal Membrane ◽  
Pars Recta ◽  
Pars Convoluta

The characteristics of renal transport of glycine by luminal membrane vesicles isolated from either proximal convoluted part (pars convoluta) or proximal straight part (pars recta) of rabbit proximal tubule were investigated. In vesicles from pars convoluta two transport systems have been characterized: a Na(+)-dependent system with intermediate affinity (half-saturation 3.64 mM) and a Na(+)-independent system that, in the presence of H+ gradient (extravesicular greater than intravesicular), can accelerate the transport of glycine into these vesicles. This is the first demonstration of H(+)-glycine cotransport across the luminal membrane of rabbit kidney proximal convoluted tubule. By contrast, in membrane vesicles from pars recta, transport of glycine was strictly dependent on Na+ and occurred via a dual transport system, namely a high-affinity (half-saturation 0.34 mM) and a low-affinity system (half-saturation 8.56 mM). The demonstration of competition between the H(+)-gradient dependent uptake of glycine, L-alanine, and L-proline, but insignificant inhibition with L-phenylalanine in vesicles from pars convoluta suggests that glycine, L-proline, and L-alanine probably share a common proton gradient-dependent transport system. In vesicles from pars recta, the Na(+)-dependent uptake of glycine was inhibited by low concentrations of L-alanine and L-phenylalanine, whereas addition of L-proline to the incubation medium did not significantly alter the uptake of glycine, suggesting that the Na(+)-dependent high-affinity system for glycine located in pars recta is shared with the high-affinity L-alanine and L-phenylalanine but not L-proline transport system.

scholarly journals Renal transport of monocarboxylic acids. Heterogeneity of lactate-transport systems along the proximal tubule

1984 ◽  
Vol 223 (3) ◽  
pp. 803-807 ◽  
Author(s):  
K E Jørgensen ◽  
M I Sheikh
Keyword(s):  
Proximal Tubule ◽  
Transport System ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Rabbit Kidney ◽  
Lactate Transport ◽  
Physiological Importance ◽  
High Affinity ◽  
Pars Recta ◽  
Pars Convoluta

The characteristics of D- and L-lactate transport in luminal-membrane vesicles derived from whole cortex, from the pars convoluta and from the pars recta of rabbit kidney proximal tubule were studied. It was found that uptake of both isomers in vesicles from whole cortex occurred by means of dual electrogenic transport systems, namely a low-affinity system and a high-affinity system. Uptake of both isomers in vesicles from the pars recta was strictly Na+-dependent and is mediated via a single high-affinity common transport system. Vesicles from the pars convoluta contained a cation-dependent but Na+-unspecific low-affinity common transport system for these compounds. The physiological importance of this system is briefly discussed.

scholarly journals Renal transport of neutral amino acids. Tubular localization of Na+-dependent phenylalanine- and glucose-transport systems

1984 ◽  
Vol 220 (1) ◽  
pp. 15-24 ◽  
Author(s):  
U Kragh-Hansen ◽  
H Røigaard-Petersen ◽  
C Jacobsen ◽  
M I Sheikh
Keyword(s):  
Glucose Transport ◽  
Transport System ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Rabbit Kidney ◽  
Outer Cortex ◽  
High Affinity ◽  
Pars Recta ◽  
Pars Convoluta ◽  
Phenylalanine Transport

The transport properties for phenylalanine and glucose in luminal-membrane vesicles from outer cortex (pars convoluta) and outer medulla (pars recta) of rabbit kidney were studied by a spectrophotometric method. Uptake of phenylalanine as well as of glucose by the two types of membrane vesicles was found to be Na+-dependent, electrogenic and stereospecific. Na+-dependent transport of L-phenylalanine by outer-cortical membrane vesicles could be accounted for by one transport system (KA congruent to 1.5 mM). By contrast, in the outer-medullary preparation, L-phenylalanine transport occurred via two transport systems, namely a high-affinity system with K1A congruent to 0.33 mM and a low-affinity system with K2A congruent to 7 mM respectively. Na+-dependent uptake of D-glucose by pars convoluta and pars recta membrane vesicles could be described by single, but different, transport systems, namely a low-affinity system with KA congruent to 3.5 mM and a high-affinity system with KA congruent to 0.30 mM respectively. Attempts to calculate the stoichiometry of the different Na+/D-glucose transport systems by using Hill-type plots revealed that the ratio of the Na+/hexose co-transport probably is 1:1 in the case of pars convoluta and 2:1 in membrane vesicles from pars recta. The Na+/L-phenylalanine stoichiometry of the pars convoluta transporter probably is 1:1. Both the high-affinity and the low-affinity Na+-dependent L-phenylalanine transport system of pars recta membrane vesicles seem to operate with a 1:1 stoichiometry. The physiological importance of the arrangement of low-affinity and high-affinity transport systems along the kidney proximal tubule is discussed.

scholarly journals Energetics of renal Na+ and H+/l-alanine co-transport systems

1988 ◽  
Vol 256 (1) ◽  
pp. 299-302 ◽  
Author(s):  
H Jessen ◽  
H Vorum ◽  
K E Jørgensen ◽  
M I Sheikh
Keyword(s):  
Indirect Evidence ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Rabbit Kidney ◽  
Luminal Membrane ◽  
Alanine Transport ◽  
Pars Recta ◽  
Dependent Transport ◽  
Pars Convoluta ◽  
Convoluted Tubules

The stoichiometric properties of Na+- and H+-dependent L-alanine transporters recently identified in luminal-membrane vesicles prepared from proximal convoluted tubules (pars convoluta) and proximal straight tubules (pars recta) of rabbit kidney were studied. We provide indirect evidence suggesting that one Na+ and one H+ ion are co-transported with the L-alanine molecule via Na+-dependent and H+-dependent transport systems located in vesicles from pars convoluta. Furthermore, our experimental data suggest that both the high-affinity and the low-affinity Na+-dependent L-alanine transport systems of pars recta vesicles operate with a 1:1 stoichiometry.

AMINO ACID TRANSPORT SYSTEMS IN BRUSH-BORDER MEMBRANE VESICLES FROM LEPIDOPTERAN ENTEROCYTES

1989 ◽  
Vol 143 (1) ◽  
pp. 87-100
Author(s):  
GIORGIO M. HANOZET ◽  
BARBARA GIORDANA ◽  
V. FRANCA SACCHI ◽  
PAOLO PARENTI
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Brush Border ◽  
Amino Acid Transport ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Acid Transport ◽  
Luminal Membrane

The presence of different potassium-dependent amino acid transport systems in the luminal membrane of the larval midgut of Philosamia cynthia Drury (Saturnidae, Lepidoptera) was investigated by means of countertransport experiments performed with brush-border membrane vesicles. The vesicles were preloaded with 14 different unlabelled amino acids, whose ability to elicit an intravesicular accumulation over the equilibrium value of six labelled amino acids (L-alanine, L-leucine, L-phenylalanine, L-glutamic acid, L-lysine and L-histidine) was tested. For histidine, the results were compared with those obtained from inhibition experiments, in which the same 14 amino acids were used as inhibitors on the cis side of the brush-border membrane. The data demonstrate the presence in the lepidopteran luminal membrane of distinct transport pathways for lysine and glutamic acid. The transport of most neutral amino acids, with the exclusionof glycine and proline, seems to occur through a system that may be similar to the neutral brush-border system (NBB) found in mammalian intestinal membranes. This system is also able to handle histidine.

Transport of L-proline by luminal membrane vesicles from pars recta of rabbit proximal tubule

1988 ◽  
Vol 254 (5) ◽  
pp. F628-F633
Author(s):  
H. Roigaard-Petersen ◽  
C. Jacobsen ◽  
M. I. Sheikh
Keyword(s):  
Active Site ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Renal Transport ◽  
High Affinity ◽  
Luminal Membrane ◽  
Transport Studies ◽  
Straight Tubules ◽  
Pars Recta ◽  
Maximal Capacity

The mechanism of renal transport of L-proline by luminal membrane vesicles prepared from proximal straight tubules (pars recta) of rabbit kidney was investigated. The following picture emerges from transport studies: an electrogenic and Na+-requiring system confined to this region of nephron exists for transport of L-proline with a high affinity (Km = 0.16 mM) and low capacity (Vmax = 3.5 nmol.mg protein-1.15 S-1). Lowering the pH from 7.5 to 5.5 increased the affinity (Km lowered from 0.16 mM at pH 7.5 to 0.08 mM at pH 5.5) without changing the maximal capacity of this system. Modification of histidyl residues of the intact luminal membrane vesicles by diethyl-pyrocarbonate (DEP) completely abolished the transient renal accumulation of L-proline. Simultaneous presence of Na+ and L-proline (10 mM) protects against DEP inactivation of renal transport of radioactive L-proline. We propose that a histidyl residue may be at or close to the active site of L-proline transporter in vesicles from the pars recta.

Anionic amino acid transport systems in isolated basal plasma membrane of human placenta

1990 ◽  
Vol 259 (1) ◽  
pp. C47-C55 ◽  
Author(s):  
S. D. Hoeltzli ◽  
L. K. Kelley ◽  
A. J. Moe ◽  
C. H. Smith
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Transport Systems ◽  
Acid Transport ◽  
Plasma Membrane Vesicles ◽  
Basal Plasma Membrane ◽  
Sodium Dependent ◽  
Basal Plasma ◽  
Potassium Gradient

The placenta absorbs anionic amino acids from the maternal and fetal circulations but does not significantly transfer these amino acids from mother to fetus. Uptake of L-aspartate and L-glutamate by basal (fetal-facing) plasma membrane vesicles from placental syncytiotrophoblast was stimulated by an inward sodium and an outward potassium gradient. Measurable saturable uptake was entirely sodium dependent and electrogenic. Studies of concentration dependence resolved a high-affinity (microM) system that has characteristics of the X-AG system found in other tissues including the placental microvillous plasma membrane. Uptake of 0.2 microM L-glutamate was inhibited by 2 mM L-glutamate, L-aspartate, D-aspartate, L-cysteate, and L-cysteinesulfinic acid and was uninhibited by 2 mM D-glutamate, L-glutamine, L-alanine, L-serine, L-asparagine, and taurine or by 1 mM methylaminoisobutyric acid. The X-AG system in the two membranes of the placental syncytiotrophoblast may mediate the concentrative uptake of anionic amino acids from the maternal and fetal circulations into the placenta.

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