Intracellular calcium during photodynamic permeabilization of cardiomyocytes.
The purpose of this study was to determine whether an early increase in [Ca2+]i preceding generalized lysis of cardiomyocytes occurred during photodynamic permeabilization. A method was developed which facilitated the simultaneous measurement, in real time, of permeabilization of the sarcolemma to Ca2+ and Mn2+ 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 measure the rate and extent of change in [Ca2+]i. The same system was used in the presence of extracellular Mn2+ to determine how quickly the cardiomyocytes became permeable to either Mn2+ or quin-2. Calcium ions were observed to enter the myocytes prior to permeabilization of the sarcolemma to either Mn2+ or quin-2, and thus before membrane lysis. Lysis of cardiomyocytes did not appear to be dependent upon increases in [Ca2+]i. Controls were performed to rule out fluorescent artifacts. Reperfusion injury and photodynamic therapy involve both the production of free radicals and an early increase in [Ca2+]i. This study demonstrates a direct correlation between the production of reactive oxygen species and prelytic increases in [Ca2+]i in neonatal cardiomyocytes and demonstrates that this phenomenon may be common to many cell types.
Yonuschot
G
G
Department of Biochemistry, University of New England, Biddeford, ME 04005.
Vaughn
J M
JM
Novotny
J F
JF
D000634:Aminoquinolines / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D004533:Egtazic Acid / Q000494:pharmacology; D004923:Erythrosine / Q000528:radiation effects*; D005453:Fluorescence; D005609:Free Radicals; D007424:Intracellular Fluid / Q000737:chemistry; D008345:Manganese / Q000378:metabolism; D009206:Myocardium / Q000737:chemistry / Q000166:cytology*; D010100:Oxygen / Q000378:metabolism*; D010777:Photochemistry; D012508:Sarcolemma / Q000378:metabolism*
D000634:Aminoquinolines; D005609:Free Radicals; D008345:Manganese; D004533:Egtazic Acid; C035739:Quin2; D004923:Erythrosine; D010100:Oxygen; D002118:Calcium