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Updated: May 4, 2026
Highly Sensitive Measurement of Glomerular Permeability in Mice with Fluorescein Isothiocyanate-polysucrose 70
Published on: August 9, 2019
Extracellular fetal hemoglobin induces increases in glomerular permeability: inhibition with α1-microglobulin and
Kristinn Sverrisson1, Josefin Axelsson, Anna Rippe
1Dept. of Nephrology, Lund Univ., Skåne Univ. Hospital, Lund S-211 85, Sweden. Bengt.Rippe@med.lu.se.
Abstract:
Extracellular fetal hemoglobin (HbF) and adult hemoglobin (HbA) are proinflammatory and generate ROS. Increased plasma levels of extracellular HbF have recently been reported to occur in early preeclampsia. α1-Microglobulin (A1M) is a physiological heme-binding protein and radical scavenger that has been shown to counteract vascular permeability increases induced by HbA in the perfused placenta. The present study was performed to investigate whether HbF and HbA will increase glomerular permeability in vivo and to test whether A1M and tempol, a ROS scavenger, can prevent their effects. Anesthetized Wistar rats were continuously infused intravenously with either HbA, HbF, or cyano-inactivated HbF together with FITC-Ficoll-70/400, inulin, and (51)Cr-labeled EDTA for 2 h. Plasma samples and urine samples (left ureter) were taken repeatedly and analyzed by high-performance size exclusion chromatography to assess glomerular sieving coefficients for Ficoll of radius 10-80 Å. In separate experiments, A1M or tempol was given before and during Hb infusions. Extracellular HbF caused rapid, transient increases in glomerular permeability to large Ficoll molecules (50-80Å), contrary to the effects of HbA and cyano-inactivated HbF. For HbF, glomerular sieving coefficients for Ficoll of radius 60Å increased from 3.85 ± 0.85 × 10(-5) to 2.60 ± 0.96 × 10(-4) at 15 min, changes that were abrogated by tempol and reduced by A1M. In conclusion, our data demonstrate that extracellular HbF, infused systemically, can acutely increase glomerular permeability through inducing oxidative stress.
Insights
Extracellular fetal hemoglobin (HbF) increases kidney glomerular permeability, unlike adult hemoglobin (HbA). This effect, linked to oxidative stress, was reduced by α1-microglobulin (A1M) and tempol, suggesting a protective role.
Area of Science:
- Nephrology
- Hematology
- Toxicology
Background:
- Extracellular fetal hemoglobin (HbF) and adult hemoglobin (HbA) are proinflammatory and generate reactive oxygen species (ROS).
- Elevated plasma HbF levels are observed in early preeclampsia.
- α1-Microglobulin (A1M) is a heme-binding protein and radical scavenger that mitigates HbA-induced vascular permeability increases.
Purpose of the Study:
- To investigate the in vivo effects of HbF and HbA on glomerular permeability.
- To determine if A1M and tempol (a ROS scavenger) can prevent Hb-induced increases in glomerular permeability.
Main Methods:
- Wistar rats were infused with HbA, HbF, or cyano-inactivated HbF.
- Glomerular permeability was assessed using FITC-Ficoll, inulin, and (51)Cr-labeled EDTA, analyzed by high-performance size exclusion chromatography.
- A1M or tempol was administered before and during hemoglobin infusions in separate experiments.
Main Results:
- Extracellular HbF caused rapid, transient increases in glomerular permeability to large Ficoll molecules (50-80Å).
- HbA and cyano-inactivated HbF did not significantly alter glomerular permeability.
- Tempol completely abrogated HbF-induced permeability changes, while A1M partially reduced them.
Conclusions:
- Systemically infused extracellular HbF acutely increases glomerular permeability.
- The mechanism involves the induction of oxidative stress.
- A1M and tempol show potential in mitigating HbF-induced kidney damage.
