TMRM (Cat.No. PK-CA707-70017) and TMRE (Cat.No. PK-CA707-70016) are said to be the preferred dyes for quantitative measurements of membrane potentials using Nernst equation. The dyes do not form aggregates in cell membranes and interact with membrane proteins minimally. Thus, the transmembrane distribution of the dyes is directly related to the membrane potential via Nernst equation.