The uptake and depletion of alpha- and gamma-tocopheryl quinone separately (A) and together (B) by RAW264.7 Macrophages. Confluent RAW264.7 macrophages were incubated with either 0.6 μM alpha-tocopheryl quinone or 0.4 μM gamma-tocopheryl quinone (A) or with both quinones (0.6 μM alpha- plus 0.4 μM gamma-tocopheryl quinone) together (B) and uptake measured during 6 hours of incubation. After 6 hours, the medium was removed and replaced with medium not containing quinones and quinone depletion followed for 4 hours. Tocopheryl quinones in the medium and cells were immediately determined by HPLC with an electrochemical detector as described in the Methods section. Values are the means ± SD of three wells. Each experiment was performed twice with excellent reproducibility.