Heat production by the mitochondria in living HeLa cells.

<p>A) Confocal fluorescence images of the cell-permeable FPT (green) and MitoTracker Deep Red FM (red), and a transmitted light image, and a FLIM image of HeLa cells. A square in the leftmost image indicates the region of interest, of which fluorescence lifetime was analyzed (in the rightmost figure). Arrowheads in the FLIM image denote local heat production, and N indicates the nucleus (the area of the nucleus is indicated by a dotted line). The temperature of the medium was maintained at 30°C. Scale bars = 10 μm (for the leftmost fluorescence image and transmission image) or 2 µm (for the enlarged fluorescence image at the second from the right and the FLIM image). B) An increase in the intracellular temperature after the inhibition of ATP synthesis by the uncoupler CCCP. FLIM images and histograms of the fluorescence lifetime of cells in the field of view after a treatment of control DMSO (left column) and CCCP (right column). Scale bars = 10 μm.