Diffusional water permeability (PDW) of adult and neonatal rabbit renal brush border membrane vesicles

J. Mulder, M. Baum, R. Quigley

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

We have shown that there is a maturational increase in osmotic water permeability (Pf) of rabbit renal brush border membrane vesicles (BBMV). The purpose of the present study was to further investigate the changes in proximal tubule water transport that occur during postnatal development. Diffusional water permeability (PDW) has not been measured directly in adult or neonatal BBMV. We validated the method described by Ye and Verkman (Simultaneous optical measurement of osmotic and diffusional water permeability in cells and liposomes. Biochemistry 28:824-829, 1989) to measure PDW in red cell ghosts and liposomes, to examine the maturational changes in PDW in BBMV. This method utilizes the sensitivity of 8-amino-naphtalene-1,3,6-trisulfonic acid (ANTS) fluorescence to the D2O-H2O content of the solvent. ANTS-loaded neonatal (11 days old) and adult BBMV were rapidly mixed with two volumes of isoosmotic D2O solution using a stopped-flow apparatus at 5°-37°C. PDW was lower in neonatal than adult BBMV at 5° (3.77 ± 0.34 vs. 5.35 ± 0.43 μm/sec, respectively, p < 0.05) and 20°C (7.03 ± 0.40 vs. 9.04 ± 0.25 μm/sec, respectively, p < 0.001), but was not different at 30° and 37°C. The activation energy (Ea) was higher in neonatal than in adult BBMV (9.29 ± 0.56 kcal/mol vs. 6.46 ± 0.56 kcal/mol, p < 0.001). In adult BBMV, PDW was inhibited by 0.5 mM HgCl2 by 46.6 ± 3.6%, while it was not affected in neonatal BBMV (p < 0.001). The results indicate that PDW can be measured in rabbit renal BBMV. There are significant changes in water transport across the apical membrane during postnatal development, consistent with a maturational increase in channel-mediated water transport.

Original languageEnglish (US)
Pages (from-to)167-174
Number of pages8
JournalJournal of Membrane Biology
Volume187
Issue number3
DOIs
Publication statusPublished - Jun 1 2002

    Fingerprint

Keywords

  • Development
  • Fluorescence
  • Membrane transport
  • Stop-flow kinetics

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

Cite this