Effect of mitochondrial energetic state on radiation-induced DNA internucleosomal fragmentation in irradiated thymocytes

One of the earliest features of apoptosis is a decrease of mitochondrial membrane potential. Here we show that when apoptosis is induced in thymocytes by ionizing radiation, inhibitors of mitochondrial energy production suppress DNA internucleosomal fragmentation. The suppression of fragmentation by inhibitors does not correlate with their effect on mitochondrial membrane potential, as it was observed when membrane potential was decreased (in the presence of inhibitors of respiratory chain, uncouplers of oxidative phosphorylation) or non affected (in the presence of oligomycin, inhibitor of mitochondrial ATPase).