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Early increase in intracellular calcium during photodynamic permeabilization
1Department of Biochemistry, University of New England, Biddeford, ME 04005.
Free Radical Biology & Medicine
|January 1, 1991
Summary
Increased intracellular calcium (Ca++) is an early event in photodynamic permeabilization of thymocytes. This calcium influx precedes cell membrane permeability to ethidium bromide, manganese (Mn++), or quin-2, and subsequent cell lysis.
Area of Science:
- Cell Biology
- Biophysics
- Photochemistry
Background:
- Photodynamic action can induce cell membrane permeabilization and lysis.
- Understanding the sequence of events during photodynamic permeabilization is crucial for controlling cellular responses.
Purpose of the Study:
- To investigate whether an early increase in intracellular calcium (Ca++) precedes thymocyte lysis during photodynamic permeabilization.
- To establish the temporal relationship between calcium influx and other membrane permeability events.
Main Methods:
- Developed a method for simultaneous real-time measurement of thymocyte membrane permeability to Ca++, Mn++, and ethidium bromide during photodynamic action.
- Utilized Quin-2 fluorescence to monitor intracellular Ca++ changes.
- Employed ethidium bromide fluorescence to detect cell membrane permeabilization.
- Measured Mn++ permeability in the presence of extracellular manganese.
Main Results:
- An early increase in intracellular Ca++ was observed following illumination.
- This Ca++ increase preceded membrane permeabilization to ethidium bromide, Mn++, and quin-2.
- Cell lysis was also observed to occur after the initial Ca++ influx.
Conclusions:
- Increased intracellular Ca++ is an early and preceding event in the photodynamic permeabilization of thymocytes.
- The findings provide insights into the mechanism of photodynamic cell damage.
- This study establishes a critical early step in the cascade leading to cell death via photodynamic action.