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Superficial membrane -SH groups inaccessible by intracellular GSH
Current Eye Research
|June 1, 1986
Summary
Membrane sulfhydryl (SH) groups on the rabbit lens surface are crucial for calcium regulation. External glutathione (GSH) protects these SH groups, maintaining lens barrier function and normal calcium levels.
Area of Science:
- Ophthalmology
- Cell Biology
- Biochemistry
Background:
- Membrane sulfhydryl (-SH) groups play a vital role in cellular functions.
- The specific role of -SH groups in the rabbit lens barrier properties requires elucidation.
Purpose of the Study:
- To investigate the function of membrane -SH groups in the rabbit lens.
- To determine the impact of sulfhydryl reagents on lens calcium permeability.
- To assess the protective role of glutathione (GSH) against alterations in lens barrier function.
Main Methods:
- Employing parachloromercuribenzoate sulfonic acid (PCMBS), a non-penetrating sulfhydryl reagent.
- Treating rabbit lens surfaces with PCMBS and measuring subsequent calcium influx.
- Assessing the effects of external GSH and cysteine on PCMBS-bound -SH groups and lens calcium levels.
Main Results:
- PCMBS treatment significantly increased calcium influx across both anterior and posterior lens surfaces.
- Intracellular GSH did not prevent PCMBS binding to membrane -SH groups.
- External GSH and cysteine rapidly reversed PCMBS binding, restoring near-normal lens calcium levels.
Conclusions:
- Externally located membrane -SH groups are critical for controlling lens barrier properties.
- Aqueous humor GSH likely plays a key role in maintaining lens membrane permeability by protecting surface -SH groups.
- These findings highlight the importance of the lens surface environment in maintaining ocular health.