TMRE

Tetramethylrhodamine ethyl ester perchlorate (TMRE) is widely used for labeling mitochondria in live cells but is not compatible with fixation. This lipophilic and positively charged dye rapidly permeates plasma membranes without interacting with membrane proteins and forming aggregates. TMRE selectively accumulates in active mitochondria due to their transmembrane potential. In addition to staining mitochondria for imaging purposes, TMRE is used for quantitative measurements of mitochondria membrane potential using the Nernst equation. The dye serves as a tool to study mitochondrial function changes and cell viability in response to stimuli or pharmaceuticals of interest. Mitochondrial depolarization caused by apoptosis, necrosis or other factors is characterized by decreased membrane potential and is indicated with decreased fluorescence compared to intact cells that have polarized mitochondria. TMRE applications include fluorescent microscopy, flow cytometry, microplate assays. The dye has an excitation maximum at 549 nm: it can be effectively excited by the blue (488 nm) or yellow-green (561 nm) lasers. Emission of the dye can be detected in the PE channel (maximum at 574 nm).