Renal transport of taurine in luminal membrane vesicles from rabbit proximal tubule

1991 ◽  
Vol 1064 (2) ◽  
pp. 189-198 ◽  
Author(s):  
Henrik Jessen ◽  
M. Iqbal Sheikh
Keyword(s):  
Proximal Tubule ◽  
Membrane Vesicles ◽  
Renal Transport ◽  
Luminal Membrane

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.

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.

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.

NHE3 activity and trafficking depend on the state of actin organization in proximal tubule

2001 ◽  
Vol 280 (2) ◽  
pp. F283-F290 ◽  
Author(s):  
C. Chalumeau ◽  
D. Du Cheyron ◽  
N. Defontaine ◽  
O. Kellermann ◽  
M. Paillard ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Cortical Cell ◽  
Membrane Vesicles ◽  
Cytochalasin D ◽  
The State ◽  
Protein Abundance ◽  
Transport Activity ◽  
Cortical Cells ◽  
Actin Organization ◽  
Luminal Membrane

The present study was addressed to define the contribution of cytoskeleton elements in the kidney proximal tubule Na+/H+ exchanger 3 (NHE3) activity under basal conditions. We used luminal membrane vesicles (LMV) isolated from suspensions of rat cortical tubules pretreated with either colchicine (Colch) or cytochalasin D (Cyto D). Colch pretreatment of suspensions (200 μM for 60 min) moderately decreased LMV NHE3 activity. Cyto D pretreatment (1 μM for 60 min) elicited an increase in LMV NHE3 transport activity but did not increase Na-glucose cotransport activity. Cyto D pretreatment of suspensions did not change the apparent affinity of NHE3 for internal H+. In contrast, after Cyto D pretreatment of the suspensions, NHE3 protein abundance was increased in LMV and remained unchanged in cortical cell homogenates. The effect of Cyto D on NHE3 was further assessed with cultures of murine cortical cells. The amount of surface biotinylated NHE3 increased on Cyto D treatment, whereas NHE3 protein abundance was unchanged in cell homogenates. In conclusion, under basal conditions NHE3 activity depends on the state of actin organization possibly involved in trafficking processes between luminal membrane and intracellular compartment.

scholarly journals A kinetically defined Na+/H+ antiporter within a mathematical model of the rat proximal tubule.

1995 ◽  
Vol 105 (5) ◽  
pp. 617-641 ◽  
Author(s):  
A M Weinstein
Keyword(s):  
Kinetic Model ◽  
Proximal Tubule ◽  
Membrane Vesicles ◽  
Model Calculations ◽  
Kinetic Formulation ◽  
Luminal Membrane ◽  
Least Squares Fit ◽  
Velocity Effect ◽  
Rat Proximal Tubule

The luminal membrane antiporter of the proximal tubule has been represented using the kinetic formulation of E. Heinz (1978. Mechanics and Engergetics of Biological Transport. Springer-Verlag, Berlin) with the assumption of equilibrium binding and 1:1 stoichiometry. Competitive binding and transport of NH+4 is included within this model. Ion affinities and permeation velocities were selected in a least-squares fit to the kinetic parameters determined experimentally in renal membrane vesicles (Aronson, P.S., M.A. Suhm, and J. Nee. 1983. Journal of Biological Chemistry. 258:6767-6771). The modifier role of internal H+ to enhance transport beyond the expected kinetics (Aronson, P.S., J. Nee, and M. A. Suhm. 1982. Nature. 299:161-163) is represented as a velocity effect of H+ binding to a single site. This kinetic formulation of the Na+/H+ antiporter was incorporated within a model of the rat proximal tubule (Weinstein, A. M. 1994. American Journal of Physiology. 267:F237-F248) as a replacement for the representation by linear nonequilibrium thermodynamics (NET). The membrane density of the antiporter was selected to yield agreement with the rate of tubular Na+ reabsorption. Simulation of 0.5 cm of tubule predicts that the activity of the Na+/H+ antiporter is the most important force for active secretion of ammonia. Model calculations of metabolic acid-base disturbances are performed and comparison is made among antiporter representations (kinetic model, kinetic model without internal modifier, and NET formulation). It is found that the ability to sharply turn off Na+/H+ exchange in cellular alkalosis substantially eliminates the cell volume increase associated with high HCO3- conditions. In the tubule model, diminished Na+/H+ exchange in alkalosis blunts the axial decrease in luminal HCO3- and thus diminishes paracellular reabsorption of Cl-. In this way, the kinetics of the Na+/H+ antiporter could act to enhance distal delivery of Na+, Cl-, and HCO3- in acute metabolic alkalosis.

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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