Maturational Changes in Rabbit Renal Basolateral Membrane Vesicle Osmotic Water Permeability

Maturational Changes in Rabbit Renal Basolateral Membrane Vesicle Osmotic Water Permeability We have recently demonstrated that while the osmotic water permeability (P f ) of neonatal proximal tubules is higher than that of adult tubules, the P f of brush-border membrane vesicles from neonatal rabbits is lower than that of adults. The present study examined developmental changes in the water transport characteristics of proximal tubule basolateral membranes by determining aquaporin 1 (AQP1) protein abundance and the P f in neonatal (10–14 days old) and adult rabbit renal basolateral membrane vesicles (BLMV). At 25°C the P f of neonatal BLMV was significantly lower than the adult BLMV at osmotic gradients ranging from 40 to 160 mOsm/kg water. The activation energies for osmotic water movement were identical in the neonatal and adult BLMV (8.65 ± 0.47 vs. 8.86 ± 1.35 kcal · deg−1· mol−1). Reflection coefficients for sodium chloride and sodium bicarbonate were identical in both the neonatal and adult BLMV and were not different from one. Mercury chloride (0.5 mm) reduced osmotic water movement by 31.3 ± 5.5% in the adult BLMV, but by only 4.0 ± 4.0% in neonatal vesicles (P < 0.01). Adult BLMV AQP1 abundance was higher than that in the neonate. These data demonstrate that neonatal BLMV have a lower P f and AQP1 protein abundance than adults and that a significantly greater fraction of water traverses the basolateral membrane lipid bilayer and not water channels in neonates compared to adults. The lower P f of the neonatal BLMV indicates that the basolateral membrane is not responsible for the higher transepithelial P f in the neonatal proximal tubule. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Maturational Changes in Rabbit Renal Basolateral Membrane Vesicle Osmotic Water Permeability

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Publisher
Springer-Verlag
Copyright
Copyright © Inc. by 2000 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002320001031
Publisher site
See Article on Publisher Site

Abstract

We have recently demonstrated that while the osmotic water permeability (P f ) of neonatal proximal tubules is higher than that of adult tubules, the P f of brush-border membrane vesicles from neonatal rabbits is lower than that of adults. The present study examined developmental changes in the water transport characteristics of proximal tubule basolateral membranes by determining aquaporin 1 (AQP1) protein abundance and the P f in neonatal (10–14 days old) and adult rabbit renal basolateral membrane vesicles (BLMV). At 25°C the P f of neonatal BLMV was significantly lower than the adult BLMV at osmotic gradients ranging from 40 to 160 mOsm/kg water. The activation energies for osmotic water movement were identical in the neonatal and adult BLMV (8.65 ± 0.47 vs. 8.86 ± 1.35 kcal · deg−1· mol−1). Reflection coefficients for sodium chloride and sodium bicarbonate were identical in both the neonatal and adult BLMV and were not different from one. Mercury chloride (0.5 mm) reduced osmotic water movement by 31.3 ± 5.5% in the adult BLMV, but by only 4.0 ± 4.0% in neonatal vesicles (P < 0.01). Adult BLMV AQP1 abundance was higher than that in the neonate. These data demonstrate that neonatal BLMV have a lower P f and AQP1 protein abundance than adults and that a significantly greater fraction of water traverses the basolateral membrane lipid bilayer and not water channels in neonates compared to adults. The lower P f of the neonatal BLMV indicates that the basolateral membrane is not responsible for the higher transepithelial P f in the neonatal proximal tubule.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Mar 1, 2000

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