Pluronic F-127 is a nonionic, surfactant polyol (molecular weight approximately 12,500 daltons) that has been found to facilitate the solubilization of water-insoluble dyes and other materials in physiological media. Pluronic F-127 is commonly used to help disperse the acetoxymethyl (AM) esters of ion indicators as well as the lipophilic tracers. Pluronic F-127 is supplied as 2 g solid (C020) and 20% (w/v) solution in DMSO (C021).