TY - JOUR AU - D'Amore, Claudio AU - Orso, Genny AU - Fusi, Fabio AU - Pagano, Mario A. AU - Miotto, Giovanni AU - Forgiarini, Alessia AU - De Martin, Sara AU - Castellani, Giulia AU - Ribaudo, Giovanni AU - Rennison, David AU - Brimble, Margaret A. AU - Hopkins, Brian AU - Ferrarese, Alessandro AU - Bova, Sergio PY - 2016 M3 - Original Research TI - An NBD Derivative of the Selective Rat Toxicant Norbormide as a New Probe for Living Cell Imaging JO - Frontiers in Pharmacology UR - https://www.frontiersin.org/articles/10.3389/fphar.2016.00315 VL - 7 SN - 1663-9812 N2 - Norbormide (NRB) is a unique compound that acts directly on rat vascular myocytes to trigger a contractile process, through an as yet unknown mechanism, which results in the selective contraction of rat peripheral arteries. To gain insight into the mechanisms involved in NRB rat-selective activity, we investigated the subcellular distribution of NRB-AF12, a nitrobenzoxadiazole (NBD)-derivative of NRB, in living NRB-sensitive and NRB-insensitive cells. In both cell types, NRB-AF12 localized to the endoplasmic reticulum (ER), Golgi apparatus, mitochondria, lysosomes, and endosomes; however, in NRB-sensitive cells, the fluorescence also extended to the plasma membrane. NRB-AF12 was rapidly internalized into the cells, could easily be washed out and then reloaded back into the same cells, all with a high degree of reproducibility. Cells exposed for 24 h to NRB-AF12 did not show apparent signs of toxicity, even at concentrations of the dye (10 μM) much higher than those required for fluorescence labeling (500 ηM). The distribution pattern of NRB-AF12 fluorescence was near identical to that of ER-Tracker® (Er-Tr), a fluorescent derivative of glibenclamide, a known KATP channel blocker. Displacement tests did not demonstrate, but at the same time did not rule out the possibility of a common target for ER-Tr, NRB-AF12, NRB, and glibenclamide. On the basis of these results we hypothesize a common target site for NRB-AF12 and ER-Tr, and a similar target profile for NRB and glibenclamide, and propose NRB-AF12 as an alternative fluorescence probe to ER-Tracker. Furthermore, NRB-based fluorescence derivatives could be designed to selectively label single cellular structures. ER -