A new method to study activated oxygen species induced damage in cardiomyocytes and protection by Ca2+-antagonists.
It has been proposed that oxygen derived free radicals contribute to reperfusion injury in ischemic tissue: radical induced lipid peroxidation is believed to cause membrane destruction, eventually evolving to cell death. A method is introduced which investigates the effect of exogenously generated reactive O2 species on isolated Ca2+-tolerant rat cardiomyocytes. Singlet oxygen (O2(1)), generated by photo-excitation of the photosensitive dye rose bengal, induced the transformation of elongated rod-shaped cells into hypercontracted rounded cardiomyocytes. These shape changes were prevented by removal of extracellular Ca2+ or by addition of radical scavengers. Pre-treatment with various classes of Ca2+-antagonists dose-dependently reduced the number of hypercontracted cardiomyocytes after exposure to O2(1). Compounds not active on the slow Ca2+-channel (e.g. flunarizine-like) provided a better degree of protection than the genuine slow Ca2+-channel blockers (e.g. dihydropyridines). Ultrastructurally, cardiomyocytes exposed to O2(1) showed a loss of cytochemically demonstrable sarcolemma-associated Ca2+ and the presence of clustered Ca2+-deposits in the mitochondria. Drug pre-treated cells displayed a Ca2+-distribution pattern comparable to unchallenged control cells.
Ver Donck
L
L
Department of Cardiovascular Pathophysiology, Janssen Research Foundation, Beerse, Belgium.
Van Reempts
J
J
Vandeplassche
G
G
Borgers
M
M
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D005609:Free Radicals; D008027:Light; D008954:Models, Biological; D015428:Myocardial Reperfusion Injury / Q000209:etiology* / Q000378:metabolism; D009206:Myocardium / Q000648:ultrastructure; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D012395:Rose Bengal / Q000494:pharmacology
D002121:Calcium Channel Blockers; D005609:Free Radicals; D012395:Rose Bengal; D010100:Oxygen