Early increase in intracellular calcium during photodynamic permeabilization.
The purpose of this study was to determine if there was an early increase in intracellular Ca++ which preceded generalized lysis of thymocytes during photodynamic permeabilization. A method was developed that facilitated the simultaneous measurement in real time of permeabilization of the thymocyte cell membrane to Ca++, Mn++, and ethidium bromide during photodynamic action. Quin-2 loaded cells were illuminated in the presence of erythrosin B and the change in the fluorescence emission of the calcium-quin-2 complex was used to determine how soon and to what extent intracellular Ca++ changed following illumination. In the presence of extracellular manganese, the same system was used to determine how soon the cells became permeable to Mn++ or quin-2. It was determined that the fluorescence emission of the ethidium bromide-DNA complex was strong enough to be measured in the presence of the calcium-quin-2 complex. This enabled the concomitant determination of the elapsed time following illumination before ethidium bromide entered the cell. It was established that increased intracellular Ca++ was an early event in the photodynamic permeabilization of thymocytes that preceded permeabilization of the cell membrane to ethidium bromide, Mn++ or quin-2, or lysis.
Department of Biochemistry, University of New England, Biddeford, ME 04005.
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Yonuschot
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000528:radiation effects*; D004996:Ethidium / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism / Q000528:radiation effects; D005260:Female; D008027:Light; D008297:Male; D008345:Manganese / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D013050:Spectrometry, Fluorescence
D008345:Manganese; D004996:Ethidium; D002118:Calcium