Uptake and cytofluorescence localization of ellipticine derivatives in sensitive and resistant Chinese hamster lung cells.

Uptake of two ellipticine derivatives, 2-N-methyl-ellipticinium (NME) and 2-N-methyl-9-hydroxy-ellipticinium, by sensitive and resistant Chinese hamster lung cells was studied. The results show that uptake and retention of these molecules by both types of cells were identical, thus indicating that the resistance to ellipticines, in this system, is not related to an impaired permeability of the cells to the drugs. However, influx and efflux kinetics, as well as experiments at increasing external concns, showed that both drugs accumulate within the cells in different ways. A cellular overconcentration of the drugs, which does not require an energy-dependent process, is observed. Fluorescence microscopy showed that, in both sensitive and resistant cells, NME is mainly, if not entirely, located in the cytoplasm.