RT-AM is a pro-drug real thiol. Real Thiol is a reversible reaction-based fluorescent probe which can quantitatively monitor the real-time glutathione dynamics in living cells.
To enhance the cell permeability of Real Thiol, the carboxylic acid groups is converted to acetoxymethyl (AM) esters, which are readily hydrolysed by esterases to regenerate Real Thiol inside cells. For cells treated with the RT-AM, real-time ratiometric images of the rapid changes of intracellular GSH concentrations in single cells can be generated by dividing the fluorescence intensity values for the 405 nm channel by the 488 nm channel at each corresponding pixel[1].
[1]. Jiang X, et al. Quantitative real-time imaging of glutathione. Nat Commun. 2017 Jul 13;8:16087.