VISUALIZATION OF DOXORUBICIN-INDUCED OXIDATIVE STRESS IN ISOLATED CARDIAC MYOCYTES

The paper presents high-resolution fluorescence images obtained using laser-scanning confocal microscopy. Isolated cells from adult rat hear ts were preloaded with 2',7'-dichlorofluorescin (an oxidant-sensitive fluorescent probe) and exposed to doxorubicin, an important anticancer drug with prominent cardiotoxicity. Fluorescence images were collecte d from live cells simultaneously on two channels: 1) 515-530 nm emissi on range was used to monitor an increase in dichlorofluorescein, the o xidized product of dichlorofluorescin, and 2) emission > 610 nm was us ed to visualize the intracellular distribution of doxorubicin. The ima ges reveal intracellular oxidation close to the mitochondria after onl y 20 min of exposure of isolated cardiomyocytes to 40-160 mu M doxorub icin. The data confirm an oxidative mechanism of doxorubicin cardiotox icity and demonstrate the capability of a new technique to monitor int racellular oxidation in living cardiomyocytes.