title: Probenicid inhibition of fluorescence extrusion after MCB-staining of rat-1 fibroblasts.
abstract: The intracellular fluorescence level of cells stained continuously with monochlorobimane was monitored by flow cytometry in order to assess the initial rate of glutatione to monochlorobimane conjugation as a measure of glutathione S-transferase activity. In addition to a rapid initial increase and a plateau level, a decline in fluorescence intensity was found upon prolonged flow cytometric monitoring. Exposure to probenicid, an inhibitor of an ATP-dependent organic anion pump, prevented this decrease. Incubation with vanadate and verapamil was without effect. Thus, extrusion of fluorescentglutathione-conjugate perturbs the proportionality between initial glutathione level and monochlorobimane-dependent fluorescence intensity. Monitoring by flow cytometry the decrease in monochlorobimane-dependent fluorescence may be useful to detect multidrug resistant cells.
authors.affiliation: Department of Human Genetics, University of Würzburg, 97074 Würzburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Poot
authors.forename: F N
authors.initials: FN
authors.lastname: Hudson
authors.forename: A
authors.initials: A
authors.lastname: Grossmann
authors.forename: P S
authors.initials: PS
authors.lastname: Rabinovitch
authors.forename: T J
authors.initials: TJ
authors.lastname: Kavanagh
mesh_terms: D016475:3T3 Cells; D000818:Animals; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005434:Flow Cytometry / Q000379:methods*; D005982:Glutathione Transferase / Q000378:metabolism*; D006651:Histocytochemistry / Q000379:methods*; D051379:Mice; D029365:Organic Anion Transporters, ATP-Dependent / Q000037:antagonists & inhibitors / Q000378:metabolism; D011339:Probenecid / Q000494:pharmacology*; D011720:Pyrazoles / Q000378:metabolism; D051381:Rats; D014528:Uricosuric Agents / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D029365:Organic Anion Transporters, ATP-Dependent; D011720:Pyrazoles; D014528:Uricosuric Agents; D014638:Vanadates; C059597:monochlorobimane; D014700:Verapamil; D005982:Glutathione Transferase; D011339:Probenecid