Description: TMRE (Tetramethylrhodamine ethyl ester, perchlorate) and TMRM are preferred dyes for quantitative measurements of membrane potentials using the Nernst equation. The dyes do not form aggregates in cell membranes and have minimal interaction with membrane proteins. Thus, the transmembrane distribution of the dyes is directly related to the membrane potential according to the Nernst equation. Biotium also offers TMRE, 2 mM in DMSO as a ready to use stock solution.