title: Flow cytometric analysis of the direct toxic effects of paraquat on cultured MDCK cells.
abstract: We used flow cytometry to assess the cell cycle kinetics of cultured Maden Darby canine kidney cells after exposure to paraquat. Fluorescein diacetate fluorescence was used as a marker of cell viability, while bromodeoxyuridine incorporation was detected with a monoclonal antibody and propidium iodide staining to assess DNA synthesis. Flow cytometry was performed immediately, 48 h and 96 h after exposure to paraquat for 24 h. Lactate dehydrogenase release was also measured to determine the extent of cytolysis. Flow cytometry of paraquat-treated cells showed a marked increase of the S phase population immediately after exposure, at a time when there was no increase of lactate dehydrogenase release. In contrast, the cell cycle profile returned towards normal at 48 and 96 h after paraquat exposure, but lactate dehydrogenase release increased. These findings indicate that paraquat arrested cells in the S phase and that inhibition of DNA synthesis by this agent appeared to influence cell viability because S phase block occurred before cytolysis. In addition, this method proved useful for assessing the effects of paraquat on DNA synthesis by cultured cells.
authors.affiliation: Department of Emergency and Critical Care Medicine, Kansai Medical University, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yamagami
authors.forename: M
authors.initials: M
authors.lastname: Matsubara
authors.forename: Y
authors.initials: Y
authors.lastname: Kitazawa
authors.forename: N
authors.initials: N
authors.lastname: Takeyama
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Kawamoto
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D004285:Dogs; D005434:Flow Cytometry / Q000379:methods; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis; D008297:Male; D010269:Paraquat / Q000633:toxicity*
chemical_list: D004247:DNA; D007770:L-Lactate Dehydrogenase; D010269:Paraquat