Differentiation of Promonocytic U937 Cells to Monocytes Is Associated with Reduced Mitochondrial Transport of Ascorbic Acid

Figure 1

Characterization of the U937-derived differentiated cells. (a) Counts of U937 cells exposed for increasing time intervals to 0 (open circles) or 1.3% DMSO (closed circles). (b) Undifferentiated (U-U937) and differentiated (D-U937) cells were preloaded with Rhod 2-AM, treated for 5 min with 0 or 20 μM Ry, and then exposed for 10 min to either 10 mM Cf or 200 μM peroxynitrite. Rhod 2-fluorescence was then quantified as detailed in Materials and Methods. Results represent the means ± SD calculated from at least 3 separate experiments. as compared to untreated cells, as compared to cells treated with Cf or peroxynitrite (one-way ANOVA followed by Dunnett’s test). (c) U-U937 and D-U937 cells were exposed for 15 min to 1 μM DPI or 10 μM apocynin and subsequently treated for 30 min with 100 μg/ml PMA. After treatments, the cells were analyzed for DHR-fluorescence. Results represent the means ± SD calculated from at least 3 separate experiments. and as compared to untreated cells, and as compared to cells treated with PMA (one-way ANOVA followed by Dunnett’s test). (d) [³H] arachidonic acid-labeled U-U937 and D-U937 cells were exposed for 5 min with 0 or 50 μM AACOCF₃ and then treated for 10 min with 10 μM A23187 or 200 μM peroxynitrite. After the treatments, [³H] arachidonic acid release was quantified as described in Materials and Methods. Results represent the means ± SD calculated from at least 3 separate experiments. and as compared to untreated cells, and as compared to cells treated with AA23187 or peroxynitrite (one-way ANOVA followed by Dunnett’s test).

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