Fig. 3. _m depolarization with CCCP and _m hyperpolarization with oligomycin were each detected by changes in TMRE fluorescence of individual mitochondria. (A) CCCP (1 µM, white squares, n=4) caused a large, rapid decrease in the average TMRE fluorescence compared with controls (black triangles, n=9). Oligomycin (6 µM, white circles, n=3) caused a small but significant increase in TMRE fluorescence (^**P<0.01 compared with controls). (B) Images of TMRE fluorescence from approximately 50% of a single smooth muscle cell before and after CCCP (1 µM) treatment. Left-most panel: the punctuate fluorescence comes from the TMRE signals from individual mitochondria. The loss of punctuate TMRE fluorescence in successive panels occurs as a result of the loss of TMRE from mitochondria as _m is depolarized with CCCP. Images were obtained at the time-points indicated by connecting lines to panel A. Scale bars: 10 µm.