Detection of a large spontaneous increase in fluorescence in cultured hippocampal neurons after 1-hr exposure to 2.5 µM TMRM.

<p><b>a.</b> Plot of 2P fluorescence (normalized) versus time for regions of interest (ROI) over a single mitochondrion and adjacent cytosolic region. The spontaneous increase in both compartments was markedly faster (and brighter) than the average FCCP-induced responses in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058059#pone-0058059-g001" target="_blank">Figure 1a</a>. <b>b.</b> Plot of 1P fluorescence using excitation at two wavelengths (546 and 573 nm) and their ratio (573/546) before and during a spontaneous increase in TMRM fluorescence. The increase in whole cell fluorescence was slower than the individual mitochondrial response but similar to the average cellular response to FCCP shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058059#pone-0058059-g001" target="_blank">Figure 1b</a>.