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Glomerular processing of dextran sulfate during transcapillary transport
S V Vyas1, M J Burne, L M Pratt
1Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
Archives of Biochemistry and Biophysics
|August 15, 1996
Summary
Glomerular filtration of dextran sulfate depends on its concentration and sulfate levels. Cellular processing, not just charge, influences its clearance, impacting kidney function models.
Area of Science:
- Nephrology
- Biochemistry
- Physiology
Background:
- Glomerular filtration is crucial for kidney function.
- Charge and size influence molecule passage across the glomerular barrier.
- Dextran sulfate is a model molecule for studying glomerular transport.
Purpose of the Study:
- To investigate the factors affecting dextran sulfate clearance by the glomerular capillary wall.
- To elucidate the role of charge, concentration, and cellular processing in glomerular transport.
- To develop a model for glomerular capillary wall transport of dextran sulfate.
Main Methods:
- Isolated perfused kidney model.
- Fractional clearance measurements of dextran sulfate.
- Analysis of dextran sulfate desulfation in urine.
- Investigation using the lysosomotropic agent NH4Cl.
- Study of dextran sulfate-mediated release of glomerular heparan sulfate.
Main Results:
- Fractional clearance of dextran sulfate is dependent on perfusate concentration and sulfate substitution.
- Charge selectivity is observed at low concentrations but is not the sole determinant.
- A strong correlation exists between fractional clearance and urinary desulfation.
- NH4Cl partially inhibits charge selectivity and desulfation.
- Glomerular endothelial cells process dextran sulfate, affecting its transport.
Conclusions:
- Glomerular transport of dextran sulfate involves more than just charge-electrostatic interactions.
- Endothelial cell processing plays a significant role in the clearance of dextran sulfate.
- A proposed model incorporating endothelial cell processing explains differences in dextran and dextran sulfate clearance.