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

Figure 5

Mitochondrial superoxide formation, DNA strand scission, and cytotoxicity induced by peroxynitrite: different concentrations of AA are required to promote similar enhancing effects in undifferentiated and differentiated cells. Undifferentiated (U-U937) and differentiated (D-U937) cells preloaded with 10 μM (U-U937) or 60 μM (D-U937) AA in the presence of 100 μM DTT were treated for 10 (a), 30 (b), or 60 min (c) with 40 μM (U-U937) or 100 μM (D-U937) peroxynitrite in the absence or presence of rotenone or myxothiazol. These inhibitors were given to the cells 3 min after peroxynitrite. After treatments, the cells were analyzed for MitoSOX red-fluorescence (a), DNA damage, (b) or cytotoxicity (c). Results represent the means ± SD calculated from at least 3 separate experiments. as compared to untreated cells, as compared to cells preexposed to AA and treated with peroxynitrite (one-way ANOVA followed by Dunnett’s test).

(a)

(b)

(c)