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Glomerular permeability barrier in the rat. Functional assessment by in vitro methods
B S Daniels1, W M Deen, G Mayer
1Department of Medicine, University of Minnesota, Minneapolis 55455.
The Journal of Clinical Investigation
|August 1, 1993
Summary
Glomerular filtration depends on hemodynamic forces and barrier properties. Study shows kidney cells, not just the basement membrane, significantly determine filtration resistance and permeability.
Area of Science:
- Nephrology
- Renal Physiology
- Molecular Biology
Background:
- Glomerular ultrafiltrate formation relies on microcirculation hemodynamics and filtration barrier properties.
- Directly assessing glomerular filtration barrier permeability is challenging with current methods.
Purpose of the Study:
- To quantify the contribution of glomerular cells and basement membrane to macromolecular and hydraulic permeability.
- To investigate the role of cellular components in glomerular filtration resistance.
Main Methods:
- Confocal microscopy of intact and acellular isolated glomeruli to assess dextran diffusion.
- Quantification of dextran permeance and sieving coefficients.
- Measurement of hydraulic permeability under applied pressure.
Main Results:
- Acellular filtration barriers showed 11 times greater dextran permeance than intact capillaries.
- Glomerular cells contribute 90% of the total resistance to macromolecular permeance.
- Cells significantly reduced both macromolecular and hydraulic permeability.
Conclusions:
- While the glomerular basement membrane restricts permeability, glomerular cells are critical determinants of overall filtration.
- Understanding cellular contributions is key to comprehending glomerular filtration and related diseases.