Ethidium bromide resistance in a rat liver epithelial cell line: association with enhanced drug efflux.
Ethidium bromide-resistant cell strains were obtained by continuous selection of an adult rat liver-derived cell line (ARL6T) grown in the continuous presence of 200 ng/ml ethidium bromide. Comparison of resistant strains and parental (sensitive) cells was made for uptake and binding of ethidium bromide, visualized as fluorescent ethidium bromide-nucleic acid complexes. Although uptake of ethidium bromide was similar in parental and resistant cells, efflux kinetics were markedly different. Over a three-hour period, parental (sensitive) cells maintained fluorescence following a short ethidium bromide pulse (100 micrograms/ml ethidium bromide). In contrast, ethidium bromide-resistant cell lines eliminated photographically detectable fluorescent complexes within three hours following pulse exposure to ethidium bromide. The rapid elimination of ethidium bromide-fluorescent complexes in all (5) resistant cell strains examined supports an efflux mechanism as contributing to the resistance of ethidium bromide cytotoxicity in these cells.
Berman
J J
JJ
Department of Pathology, University of Maryland School of Medicine, Baltimore.
D000818:Animals; D002460:Cell Line; D004351:Drug Resistance; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects; D004996:Ethidium / Q000494:pharmacology*; D008099:Liver / Q000166:cytology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D004996:Ethidium