A pH-dependent fluorescent probe to label dopaminergic cells; excitation spectra of 340 and 370 nm at pH 5 and 7.4, respectively, which correspond to vesicular and cytoplasmic pH values; emission spectrum of 453 nm, with a higher intensity at pH 7.4; inhibits DAT (13.6% at a concentration of 10 μM) and the 5-HT receptor subtype 5-HT2c (Ki = ~3 μM); does not bind to 37 central nervous system receptors, including dopamine and serotonin receptors, up to a concentration of 10 μM