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

Figure 2

SVCT1 and SVCT2 expression and cellular uptake of AA in undifferentiated and differentiated cells. (a) RT-PCR analysis of SVCT1 and SVCT2 mRNA in undifferentiated (U-U937) and differentiated (D-U937) cells. (b) SVCT1 and SVCT2 protein expression determined by Western blot analysis of samples obtained from U937 cells grown for 0–96 h in the presence of DMSO. Anti-actin antibodies were used to provide an internal loading control. Relative amounts of SVCT1 and SVCT2 were determined by densitometric analysis of three different experiments and are expressed as % of U-U937 cells. (c) Vitamin C content in U-U937 and D-U937 cells exposed for 5 min to 0–60 μM AA. (d) Effect of Na⁺ omission (and replacement with choline), pCMB, S-pyr, and cyt B on AA transport in U-U937 and D-U937 cells exposed for 5 min to 30 μM AA. Results represent the means ± SD calculated from at least three separate experiments.

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