Di-4-ANEPPS is a potentiometric fluorescent dye that can be used to measure membrane potential. It displays absorption/emission maxima of 495/705 nm, respectively. The relative fluorescence changes proportionally to membrane potential at a rate of approximately 10% per 100 mV. Di-4-ANEPPS has been used to measure membrane potential in a variety of tissue and cell types as well as artificial membranes.