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Cationic ferritin changes outflow facility in human eyes whereas anionic ferritin does not
1Department of Mechanical and Industrial Engineering, 5 King's College Road, University of Toronto, Toronto, Ontario M5S 3G8, Canada. ethier@mie.utoronto.ca
Investigative Ophthalmology & Visual Science
|June 30, 2001
Summary
Positively charged molecules, like cationic ferritin, significantly reduce aqueous humor outflow facility in human eyes by binding to the inner wall of Schlemm's canal. This suggests charged moieties play a crucial role in regulating intraocular pressure.
Area of Science:
- Ophthalmology
- Biophysics
- Cell Biology
Background:
- Aqueous humor outflow facility is critical for maintaining intraocular pressure.
- The role of charged moieties in the outflow pathway is not fully understood.
Purpose of the Study:
- To investigate the impact of charged molecules on aqueous humor outflow facility in human eyes.
- To elucidate the mechanism by which charged moieties affect Schlemm's canal function.
Main Methods:
- Human eye bank eyes were perfused with cationic or anionic ferritin to assess outflow facility.
- Transmission and scanning electron microscopy were used to visualize ferritin distribution.
- Neuraminidase was used to probe the role of sialyl residues.
Main Results:
- Cationic ferritin significantly reduced outflow facility by 66% (P < 0.00001).
- Anionic ferritin had a negligible effect on outflow facility.
- Cationic ferritin accumulated on the inner wall of Schlemm's canal, potentially blocking intercellular clefts.
Conclusions:
- Positively charged molecules, such as cationic ferritin, can markedly reduce aqueous humor outflow facility.
- Binding to negatively charged sites in the outflow pathway, particularly the inner wall of Schlemm's canal, is a key mechanism.
- Charged moieties are important regulators of aqueous humor dynamics and intraocular pressure.