Sensitivity of flavoprotein fluorescence to oxidative state in single isolated heart cells

The contribution of flavoprotein fluorescence to redox sensitive cellular autofluorescence was studied in single isolated adult rat heart cells. Fluorescence was measured quantitatively under conditions stimulating flavoprotein fluorescence in cells subjected to no inhibitors (sham), to cyanide, to 2,4-dinitrophenol, and to hypoxia. It was found that fluorescence apparently due to flavoproteins could be measured in single cells, and the fluorescence was sensitive to the redox state of the cell. Comparison with NADH fluorescence from single cells indicated that, while flavoprotein fluorescence was less intense, excitation of flavoproteins caused less bleaching of fluorescence when compared to the effect of excitation on NADH fluorescence.