H+-L-proline cotransport by vesicles from pars convoluta of rabbit proximal tubule

1987 ◽  
Vol 253 (1) ◽  
pp. F15-F20 ◽  
Author(s):  
H. Roigaard-Petersen ◽  
C. Jacobsen ◽  
M. Iqbal Sheikh
Keyword(s):  
Proximal Tubule ◽  
Membrane Vesicles ◽  
Ph Gradient ◽  
Rabbit Kidney ◽  
Renal Transport ◽  
Physiological Importance ◽  
Luminal Membrane ◽  
Pars Convoluta ◽  
Convoluted Tubules ◽  
Stimulation Of

The mechanism of renal transport of L-proline by luminal-membrane vesicles isolated from proximal convoluted tubules of rabbit kidney was studied. It was found that H+ gradient (extravesicular greater than intravesicular) can drive the transport of L-proline into the vesicles both in the presence and absence of Na+. The stimulation of L-proline uptake by a pH gradient was additive with that produced by Na+. Saturation kinetic experiments revealed that pH gradient, in addition to Na+, increased the maximal uptake of L-proline by twofold. This is the first demonstration of H+-L-proline cotransport across luminal membrane of rabbit kidney proximal convoluted tubule. The physiological importance of this system 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 l-tryptophan uptake by segment-specific membrane vesicles from the proximal tubule of rabbit kidney

1992 ◽  
Vol 286 (1) ◽  
pp. 103-110 ◽  
Author(s):  
H Jessen ◽  
M I Sheikh
Keyword(s):  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Basolateral Membrane Vesicles ◽  
Luminal Membrane ◽  
Transport Component ◽  
Pars Recta ◽  
Dependent Transport ◽  
Pars Convoluta

1. The mechanism of the renal transport of L-tryptophan by basolateral and luminal membrane vesicles prepared from either the pars convoluta or the pars recta of the rabbit proximal tubule was studied. The uptake of L-tryptophan by basolateral membrane vesicles from the pars convoluta was found to be an Na(+)-dependent transport event. The Na(+)-conditional influx of the amino acid was stimulated in the presence of an inwardly directed H+ gradient. Lowering the pH without an H+ gradient had no effect, indicating that L-tryptophan is co-transported with H+. 3. On the other hand, no transient accumulation of L-tryptophan was observed in the presence or absence of Na+ in basolateral membrane vesicles from the pars recta. 4. In luminal membrane vesicles from the pars recta, the transient Na(+)-dependent accumulation of L-tryptophan occurred via a dual transport system. In addition, an inwardly directed H+ gradient could drive the uphill transport of L-tryptophan into these vesicles in both the presence and the absence of an Na+ gradient. 5. By contrast, the uptake of L-tryptophan by luminal membrane vesicles from the pars convoluta was a strictly Na(+)-dependent and electrogenic transport process, mediated by a single transport component. 6. Investigation of the coupling ratio in luminal membrane vesicles suggested that 1 Na+:1 L-tryptophan are co-transported in the pars convoluta. In the pars recta, examination of the stoichiometry indicated that approx. 1 H+ and 2 Na+ (high affinity) or 1 Na+ (low affinity) are involved in the uptake of L-tryptophan.

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 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.

scholarly journals Stoichiometric studies of β-alanine transporters in rabbit proximal tubule

1991 ◽  
Vol 277 (3) ◽  
pp. 891-894 ◽  
Author(s):  
H Jessen ◽  
M I Sheikh
Keyword(s):  
Indirect Evidence ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Coupling Ratio ◽  
Beta Alanine ◽  
Luminal Membrane ◽  
Straight Tubules ◽  
Pars Recta ◽  
Pars Convoluta ◽  
Convoluted Tubules

The coupling ratio for the transport of beta-alanine and Na+, H+ and Cl- in luminal membrane vesicles isolated from proximal convoluted tubules (pars convoluta) and proximal straight tubules (pars recta) of rabbit kidney was examined. Indirect evidence indicates that 1 H+ and approx. 2 Na+, 1 Cl- (Na(+)-dependent, high-affinity) or 1 Na+ (Na(+)-dependent, low-affinity) are co-transported with beta-alanine in the pars convoluta. In pars recta, the two Na(+)-dependent transporters exhibited the same stoichiometric properties respectively as in pars convoluta.

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.

Axial heterogeneity of apical water permeability along rabbit kidney proximal tubule

1991 ◽  
Vol 260 (1) ◽  
pp. R186-R191 ◽  
Author(s):  
F. Van Der Goot ◽  
B. Corman
Keyword(s):  
Light Scattering ◽  
Proximal Tubule ◽  
Water Permeability ◽  
Membrane Surface ◽  
Morphological Difference ◽  
Membrane Vesicles ◽  
Rabbit Kidney ◽  
Elastic Light Scattering ◽  
Membrane Area ◽  
Luminal Membrane

In the rabbit nephron, the luminal membrane surface area of the proximal convoluted tubule (PCT) is more than twice that of the proximal straight tubule (PST). What seemed to be an increase in histological specialization in solute and water transport is curiously reflected by a lower transepithelial water permeability per unit of apical membrane area in PCT than in PST. To evaluate what change in luminal membrane water permeability corresponds to this morphological difference, the osmotic permeabilities (Pf) of brush-border membrane vesicles isolated from PCT and PST of rabbit kidney were compared. D-Glucose uptake rates indicated proper separation of two populations of vesicles. Vesicle size measured by quasi-elastic light scattering was 123 +/- 7 nm and 125 +/- 6 nm for vesicles isolated from PCT and PST, respectively. Pf obtained by stop-flow light scattering techniques was of 106 +/- 6 microns/s in PCT vesicles and 191 +/- 7 microns/s in PST vesicles (T = 26 degrees C). In the presence of the sulfhydryl reagent HgCl2, the water permeabilities of both types of membrane dropped to comparable values. These data, which show an 80% increase in apical water permeability along the length of the proximal tubule, suggest that the number of proteic water channels per unit of membrane area is greater in PST than in PCT.

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