Fura-2, AM is a high affinity, intracellular calcium indicator that is ratiometric and UV light—excitable. This acetoxymethyl (AM) ester form is useful for noninvasive intracellular loading and is also available in 1 mg amounts (F-1201) and in a DMSO solution (F-1225). Cell-impermeant pentapotassium (F-1200) and pentasodium (F-6799) salt forms of the dye are available.