title: Comparison of methods for measuring oxygen consumption in tumor cells in vitro.
abstract: The oxygen consumption rate of tumor cells affects tumor oxygenation and response to therapies. Highly sensitive methods for determining cellular oxygen consumption are, therefore, needed to identify treatments that can modulate this parameter. We compared the performances of three different methods for measuring cellular oxygen consumption: electron paramagnetic resonance (EPR) oximetry, the Clark electrode, and the MitoXpress fluorescent assay. To compare the assays, we used K562 cells in the presence of rotenone and hydrocortisone, compounds that are known to inhibit the mitochondrial electron transport chain to different extents. The EPR method was the only one that could identify both rotenone and hydrocortisone as inhibitors of tumor cell oxygen consumption. The Clark electrode and the fluorescence assay demonstrated a significant decrease in cellular oxygen consumption after administration of the most potent inhibitor (rotenone) but failed to show any significant effect of hydrocortisone. EPR oximetry is, therefore, the most sensitive method for identifying inhibitors of oxygen consumption on cell assays, whereas the Clark electrode offers the unique opportunity to add external compounds during experiments and still shows great sensitivity in studying enzyme and chemical reactions that consume oxygen (non-cell assays). Finally, the MitoXpress fluorescent assay has the advantage of a high-sample throughput and low bulk requirements but at the cost of a lower sensitivity.
authors.affiliation: Laboratory of Biomedical Magnetic Resonance, Louvain Drug Research Institute, Université catholique de Louvain, B-1200 Brussels, Belgium.
authors.forename: Caroline
authors.initials: C
authors.lastname: Diepart
authors.forename: Julien
authors.initials: J
authors.lastname: Verrax
authors.forename: Pedro Buc
authors.initials: PB
authors.lastname: Calderon
authors.forename: Olivier
authors.initials: O
authors.lastname: Feron
authors.forename: Bénédicte F
authors.initials: BF
authors.lastname: Jordan
authors.forename: Bernard
authors.initials: B
authors.lastname: Gallez
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D020014:K562 Cells; D008163:Luminescent Measurements / Q000379:methods; D009369:Neoplasms / Q000378:metabolism*; D010092:Oximetry / Q000379:methods*; D010101:Oxygen Consumption / Q000502:physiology*; D012402:Rotenone / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D000893:Anti-Inflammatory Agents; D014475:Uncoupling Agents; D012402:Rotenone; D006854:Hydrocortisone