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Reduced diffusion of charge-modified, conformationally intact anionic Ficoll relative to neutral Ficoll across the rat glomerular filtration barrier in vivo.

Authors :
Axelsson, Josefin
Sverrisson, Kristinn
Rippe, Anna
Fissell, William
Rippe, Bengt
Source :
American Journal of Physiology: Renal Physiology. Oct2011, Vol. 301 Issue 4, pF708-F712. 5p.
Publication Year :
2011

Abstract

The glomerular filtration barrier (GFB) is commonly conceived as a negatively charged sieve to proteins. Recent studies, however, indicate that glomerular charge effects are small for anionic, carboxymethylated (CM) dextran vs. neutral dextran. Furthermore, two studies assessing the glomerular sieving coefficients (?) for negative CM-Ficoll vs. native Ficoll have demonstrated an increased glomerular permeability for CM-Ficoll (Asgeirsson D, Venturoli D, Rippe B, Rippe C. Am J Physiol Renal Physiol 291: F1083-F1089, 2006; Guimarães M, Nikolovski J, Pratt L, Greive K, Comper W. Am Physiol Renal Physiol 285: F1118-F1124, 2003.). The CM-Ficoll used, however, showed a larger Stokes-Einstein radius (ae) than neutral Ficoll, and it was proposed that the introduction of negative charges in the Ficoll molecule had made it more flexible and permeable. Recently, a negative FITC-labeled CM-Ficoll (CMI-Ficoll) was produced with a conformation identical to that of neutral FITC-Ficoll. Using these probes, we determined their ?:s in anesthetized Wistar rats (259 ± 2.5 g). After blood access had been achieved, the left ureter was cannulated for urine sampling. Either polysaccharide was infused (iv) together with a filtration marker, and urine and plasma were collected. Assessment of ? FITC-Ficoll was achieved by high-performance size-exclusion chromatography (HPSEC). CMI-Ficoll and native Ficoll had identical elugrams on the HPSEC. Diffusion of anionic Ficoll was significantly reduced compared with that of neutral Ficoll across the GFB for molecules of ae ~20-35 Å, while there were no charge effects for Ficoll of ae = 35-80 Å. The data are consistent with a charge effect present in "small pores," but not in "large pores," of the GFB and mimicked those obtained for anionic membranes in vitro for the same probes. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
1931857X
Volume :
301
Issue :
4
Database :
Academic Search Index
Journal :
American Journal of Physiology: Renal Physiology
Publication Type :
Academic Journal
Accession number :
66778471
Full Text :
https://doi.org/10.1152/ajprenal.00183.2011