Developmental Aspects of Renal β-Amino Acid Transport. VI. The Role of Membrane Fluidity and Phospholipid Composition in the Renal Adaptive Response in Nursing Animals

Chesney, Russell W.; Gusowski, Naomi; Zelikovic, Israel

doi:10.1203/00006450-198708000-00013

Cited by 15 publications

(11 citation statements)

References 33 publications

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“…The lipid to protein content ratio decreases as the animal matures. The fractional content of phosphatidyl serine and ethanolamine increases, whereas that of phosphatidyl choline and glycerol phosphate decrease with maturation (11) . Membrane fluidity also decreases with maturation as a result of the changes in lipid composition (11,16,17) .…”

Section: Discussionmentioning

confidence: 99%

“…The lipid composition of BBMV from rat kidneys demonstrates several changes that occur during development (11) . The lipid to protein content ratio decreases as the animal matures.…”

Section: Discussionmentioning

confidence: 99%

“…The lipid composition of brush border membranes is known to change during development and may affect transport of other molecules in addition to urea (8)(9)(10)(11) . To examine this possibility, the permeability of the lipid soluble compound, glycerol, was examined.…”

Section: Glycerol Permeabilitymentioning

confidence: 99%

“…The fractional content of phosphatidyl serine and ethanolamine increases, whereas that of phosphatidyl choline and glycerol phosphate decrease with maturation (11) . Membrane fluidity also decreases with maturation as a result of the changes in lipid composition (11,16,17) . BBMV from neonatal rabbit kidneys also have a higher fluidity than BBMV from adult rabbits (9,10) .…”

mentioning

confidence: 99%

“…The lipid composition of brush border membranes also changes during development and may play a role in the maturation of transport processes (8)(9)(10)(11) . Because proximal tubule transport of urea is thought to occur via the lipid bilayer, the changes in membrane lipid composition may affect urea transport.…”

mentioning

confidence: 99%

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Maturational Changes in Rabbit Renal Brush Border Membrane Vesicle Urea Permeability • 1830

Quigley¹,

Flynn²,

Baum³

1998

Pediatr Res

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Urea transport in the proximal tubule is thought to occur by passive diffusion through the lipid bilayers of the cell membranes. The lipid composition of cell membranes changes during maturation and may directly affect urea permeability of proximal tubule membranes. The present study examined the maturation of urea transport in rabbit renal brush border membrane vesicles (BBMV). BBMV from adult and neonatal (9-to 11-d-old) New Zealand white rabbits were loaded with 500 mM urea and mixed with an iso-osmotic mannitol solution using a stop-flow instrument. Vesicle shrinkage, due to efflux of urea, was followed with light scattering and urea permeability was calculated from an exponential fit of the data. Urea permeability was significantly lower in the neonatal BBMV than the adult at 25°C (0.34 ± 0.04 × 10 −6 versus 0.56 ± 0.03 × 10 −6 cm/sec; p < 0.001, n = 7) and 37°C (0.45 ± 0.04 × 10 −6 versus 0.66 ± 0.03 × 10 −6 cm/sec; p = 0.001, n = 7). There was no effect of 250 µM phloretin on urea permeability in either adult or neonatal BBMV at either temperature. The activation energy for urea diffusion was higher in the neonatal than the adult BBMV. Because the maturational increase in urea permeability could potentially be due to a sodium-dependent urea transporter in the adult BBMV, the sodium dependence of urea uptake in adult BBMV was examined. There was no difference in urea permeability in the presence or absence of 20 mM NaCl. Permeability of the lipid-soluble molecule, glycerol, was also found to be the same in the neonatal and adult BBMV. Urea transport in the apical membrane of neonatal and adult proximal tubules is not phloretin sensitive, a finding consistent with diffusion of urea via the lipid bilayer. The rate of urea diffusion is lower in neonatal membranes and may be an important factor in overall urea excretion. This may also play a role in developing and maintaining a high medullary urea concentration and thus the ability to concentrate the urine during renal maturation.In most mammals, nitrogen waste from metabolism of amino acids is excreted in the urine as urea (1,2) . The proximal tubule reabsorbs approximately 50% of the filtered load of urea despite changes in hydration status and protein intake that alter the overall excretion of urea. Although initial studies suggested that the proximal straight tubule actively secreted urea ( and that membrane transport of urea in the proximal tubule may occur by a specific transporter (4) , most evidence indicates that urea transport in the proximal tubule occurs by passive diffusion through the lipid bilayer (1,2) . The phospholipid composition of membranes has a direct influence on solute permeabilities and thus may directly affect proximal tubule transport of urea (5) .During maturation, the proximal tubule of the rabbit is known to undergo many changes in active and passive transport characteristics (6,7) . The lipid composition of brush border membranes also changes during development and may play a role in the maturation of transport processes...

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Section: Discussionmentioning

confidence: 99%

“…The lipid composition of BBMV from rat kidneys demonstrates several changes that occur during development (11) . The lipid to protein content ratio decreases as the animal matures.…”

Section: Discussionmentioning

confidence: 99%

Section: Glycerol Permeabilitymentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Maturational Changes in Rabbit Renal Brush Border Membrane Vesicle Urea Permeability • 1830

Quigley¹,

Flynn²,

Baum³

1998

Pediatr Res

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Development of β‐amino acid transport in the kidney

et al. 1988

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This study focuses on the maturation of the renal beta-amino acid transport system and uses dietary manipulation as a probe. The epithelial surface of the renal proximal tubule is responsible for the conservation of ions and organic solutes including beta-amino acids. This beta-amino acid transport system is stimulated during periods of reduced dietary intake and permits increased excretion following dietary excess. We have examined transport of the sulfur-containing beta-amino acid, taurine, as a measure of this renal adaptive response to fluctuations in dietary sulfur amino acid intake and as a substrate for the beta-amino acid transport system. A precession of taurine uptake values by brush border membrane vesicles (BBMV) prepared from nursing rats from youngest to oldest was evident. However, these membranes demonstrate the full renal adaptive response to altered sulfur amino acid intake after the first week of life. This adaptive response is expressed at the brush border surface by transport changes in both directions ("up regulation" and "down regulation"), through changes in the initial rate (15 sec) of Na+-taurine cotransport. No alterations in the lipid microenvironment of the membrane, as detected by altered membrane fluidity, were uncovered. Although vesicles from 7-day-old pups demonstrate adaptation and accumulate taurine to a limited extent, the accumulation of Na+, which energizes uptake, may be altered, thereby preventing full expression of the adaptive response and of transport capacity at this age.

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Ionomycin Restores Taurine Transporter Activity in Cyclosporin-A Treated Macrophages

Kim

Lee

Kim

et al. 2002

Advances in Experimental Medicine and Biology

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Do 449-900, KoreaTaurine is accumulated at high concentrations in various tissues. The taurine transporter (TAUT) is responsible for the transportation of taurine in the cell. The transporter is affected by various stimuli to maintain cell volume. Macrophage cell volume varies in its activated states. In our experiment, it was found that the murine macrophage cell line, RAW264.7, expressed TAUT protein in its membrane. Its transporting activities could be blocked by -amino acid such as -alanine, but not by a-amino acids in this cell line. when assessed in RAW264.7 cells under the influence of immunosuppressive reagents, the activity of the TAUT was decreased by treatment with rapamycin (RM) or cyclosporin A (CSA). However, when ionomycin (IM) was added to this system, TAUT activity was recovered only in CSA-treated cells, in a concentrationdependent manner. in order to inhibit voltage gated Ca 2 + channels, calmidazolium was added to the RAW264.7 cell line. Treatment of the cells with calmidazolium completely blocked TAUT. Furthermore, addition of IM to this system resulted in recovery the activity of TAUT again. When we added phorbol myristyl acetate (PMA) to the cell line, secretion of nitric oxide (NO) was increased 4-fold and the TAUT activity was decreased 5-fold. However, the addition of N-nitro L-arginine methyl ester (L-NAME), an inducible NO synthase (iNOS) inhibitor, to the PMA-treated cells induced recovery of TAUT activity. These results showed that the activity of TAUT was sensitive to both the intracellular concentrations of Ca 2+ and NO.

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Developmental Aspects of Renal β-Amino Acid Transport. VI. The Role of Membrane Fluidity and Phospholipid Composition in the Renal Adaptive Response in Nursing Animals

Cited by 15 publications

References 33 publications

Maturational Changes in Rabbit Renal Brush Border Membrane Vesicle Urea Permeability • 1830

Maturational Changes in Rabbit Renal Brush Border Membrane Vesicle Urea Permeability • 1830

Development of β‐amino acid transport in the kidney

Ionomycin Restores Taurine Transporter Activity in Cyclosporin-A Treated Macrophages

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