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Physiological aspects of the glomerular filtration barrier

Sverrisson, Kristinn LU (2015) In Lund University, Faculty of Medicine Doctoral Dissertation Series 2015:50.
Abstract
Proteinuria is associated with progression of kidney disease and is an independent risk factor for cardiovascular

morbidity and mortality. The pathophysiological alterations resulting in proteinuria are obscure, although proteinuria is

often associated with pathological changes in the glomerular filtration barrier (GFB). It is therefore of great interest to

study the physiology of the GFB, in order to be able to prevent or reduce proteinuria.

The studies in this thesis were performed using an in vivo model in anesthetized rats. The rats were cannulated for blood

access and the left ureter cannulated for urine collection through a small abdominal incision. The glomerular permeability

was... (More)
Proteinuria is associated with progression of kidney disease and is an independent risk factor for cardiovascular

morbidity and mortality. The pathophysiological alterations resulting in proteinuria are obscure, although proteinuria is

often associated with pathological changes in the glomerular filtration barrier (GFB). It is therefore of great interest to

study the physiology of the GFB, in order to be able to prevent or reduce proteinuria.

The studies in this thesis were performed using an in vivo model in anesthetized rats. The rats were cannulated for blood

access and the left ureter cannulated for urine collection through a small abdominal incision. The glomerular permeability

was measured using sieving coefficients (θ) for fluorescently labeled Ficoll (FITC-Ficoll) with a molecular radius ranging

from 10Å to 80Å. The rats were infused with FITC-Ficoll, and blood- and urine samples were collected and analyzed

with high performance size exclusion chromatography (HPSEC).

In study I, the GFB charge-selectivity was explored using a negatively charged, conformationally intact anionic Ficoll

(CMI-Ficoll), comparing it to neutral Ficoll, of same Stokes-Einstein (SE) radius. The sieving of CMI-Ficoll was reduced

across the GFB compared to neutral Ficoll for molecules of radius 20-35Å. The GFB was thus found to be negatively

charged. However, the charge was of much less magnitude than previously estimated.

In study II, the proposed effects of systemic infusion of protamine sulfate (PS) and hyaluronidase (Hyase) on the GFB

charge-selectivity were studied. PS and to some extent Hyase, increased the permeability for Ficoll molecules > 50Å, but

had no effect on the charge-selectivity of the GFB.

In study III, the permeability effects of extracellular adult (HbA) and fetal hemoglobin (HbF) were studied, showing

increases in θ for macromolecules (50-80Å in radius) after infusion of HbF, but not after HbA or cyano-inactivated HbF

(CN-HbF) infusions. Tempol (a superoxide radical scavenger) and α-1-microglobulin (A1M; a physiological hemebinding

protein and radical scavenger), both prevented the increase in the permeability of the GFB.

In study IV, the effects of the pro-inflammatory cytokines, TNF-α, Il-1β and IL-6, on the GFB permeability were

studied. TNF-α and Il-1β caused a rapid, reversible, increase in glomerular permeability, while IL-6 generated a more

gradual response. These effects could be inhibited with tempol, showing a reactive oxygen species (ROS) dependency of

the cytokine effects on the GFB permeability. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Hansell, Peter, Uppsala Universitet
organization
publishing date
type
Thesis
publication status
published
subject
in
Lund University, Faculty of Medicine Doctoral Dissertation Series
volume
2015:50
pages
84 pages
publisher
Njurmedicin, Institutionen för Kliniska Vetenskaper Lund
defense location
Segerfalksalen, BMC A10, Sölvegatan 17, Lund
defense date
2015-05-20 09:00
ISSN
1652-8220
ISBN
978-91-7619-129-3
language
English
LU publication?
yes
id
7c46b18a-3152-4940-9bdb-edd088b6dd6a (old id 5323090)
date added to LUP
2015-04-29 13:46:58
date last changed
2016-09-19 08:44:46
@phdthesis{7c46b18a-3152-4940-9bdb-edd088b6dd6a,
  abstract     = {Proteinuria is associated with progression of kidney disease and is an independent risk factor for cardiovascular<br/><br>
morbidity and mortality. The pathophysiological alterations resulting in proteinuria are obscure, although proteinuria is<br/><br>
often associated with pathological changes in the glomerular filtration barrier (GFB). It is therefore of great interest to<br/><br>
study the physiology of the GFB, in order to be able to prevent or reduce proteinuria.<br/><br>
The studies in this thesis were performed using an in vivo model in anesthetized rats. The rats were cannulated for blood<br/><br>
access and the left ureter cannulated for urine collection through a small abdominal incision. The glomerular permeability<br/><br>
was measured using sieving coefficients (θ) for fluorescently labeled Ficoll (FITC-Ficoll) with a molecular radius ranging<br/><br>
from 10Å to 80Å. The rats were infused with FITC-Ficoll, and blood- and urine samples were collected and analyzed<br/><br>
with high performance size exclusion chromatography (HPSEC).<br/><br>
In study I, the GFB charge-selectivity was explored using a negatively charged, conformationally intact anionic Ficoll<br/><br>
(CMI-Ficoll), comparing it to neutral Ficoll, of same Stokes-Einstein (SE) radius. The sieving of CMI-Ficoll was reduced<br/><br>
across the GFB compared to neutral Ficoll for molecules of radius 20-35Å. The GFB was thus found to be negatively<br/><br>
charged. However, the charge was of much less magnitude than previously estimated.<br/><br>
In study II, the proposed effects of systemic infusion of protamine sulfate (PS) and hyaluronidase (Hyase) on the GFB<br/><br>
charge-selectivity were studied. PS and to some extent Hyase, increased the permeability for Ficoll molecules &gt; 50Å, but<br/><br>
had no effect on the charge-selectivity of the GFB.<br/><br>
In study III, the permeability effects of extracellular adult (HbA) and fetal hemoglobin (HbF) were studied, showing<br/><br>
increases in θ for macromolecules (50-80Å in radius) after infusion of HbF, but not after HbA or cyano-inactivated HbF<br/><br>
(CN-HbF) infusions. Tempol (a superoxide radical scavenger) and α-1-microglobulin (A1M; a physiological hemebinding<br/><br>
protein and radical scavenger), both prevented the increase in the permeability of the GFB.<br/><br>
In study IV, the effects of the pro-inflammatory cytokines, TNF-α, Il-1β and IL-6, on the GFB permeability were<br/><br>
studied. TNF-α and Il-1β caused a rapid, reversible, increase in glomerular permeability, while IL-6 generated a more<br/><br>
gradual response. These effects could be inhibited with tempol, showing a reactive oxygen species (ROS) dependency of<br/><br>
the cytokine effects on the GFB permeability.},
  author       = {Sverrisson, Kristinn},
  isbn         = {978-91-7619-129-3},
  issn         = {1652-8220},
  language     = {eng},
  pages        = {84},
  publisher    = {Njurmedicin, Institutionen för Kliniska Vetenskaper Lund},
  school       = {Lund University},
  series       = {Lund University, Faculty of Medicine Doctoral Dissertation Series},
  title        = {Physiological aspects of the glomerular filtration barrier},
  volume       = {2015:50},
  year         = {2015},
}