DiBAC4(3) (Bis-(1,3-Dibarbituric acid)-trimethine oxanol) is a so-called translational membrane potential dye that redistributes within the cell membrane when membrane potential changes. The fluorescence of the dye is enhanced when the dye enters the cell membrane as a result of membrane depolarization. The rate of fluorescence response of the dye to membrane potential change is usually slower than that of the styryl dye di-4-ANEPPS, but the fluorescence signal change for the former is significantly larger than for the latter dye. DiBAC4(3) has applications in high-throughput drug screening.