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

Figure 4

Mitochondrial superoxide formation induced by BSO: different concentrations of AA are required to promote similar protective effects in undifferentiated and differentiated cells. (a) Undifferentiated (U-U937) and differentiated (D-U937) cells were exposed for 4 h to 0 or 100 μM BSO. After treatments, the cells were analyzed for their GSH content. (b and c) The cells were treated for 4 h with BSO, in the absence or presence of rotenone (0.5 μM), myxothiazol (5 μM), DPI (1 μM), and apocynin (10 μM). These inhibitors were given to the cells 3 min prior to addition of BSO. Experiments were also performed in cells preexposed for 10 min to 10 μM or 60 μM AA prior to the 4 h exposure to BSO. The effect of AA or other inhibitors in the absence of BSO was also tested. After treatments, the cells were analyzed for DHR-fluorescence (b) or MitoSOX red-fluorescence (c). as compared to untreated cells and as compared to cells preexposed to AA and treated with BSO (one-way ANOVA followed by Dunnett’s test).

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(b)

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