Figure 5.

Transverse relaxation rates of P19 cells under various conditions of extracellular iron supplementation. Cells were cultured either in non-supplemented medium (−Fe) or iron-supplemented medium (+Fe) for at least 5–7 days before iron supplementation withdrawal and an additional 1 (1h-Fe), 2 (2h-Fe), 4 (4h-Fe) or 24 (24h-Fe) hours of culture in non-supplemented medium. (a) R₂* and (b) R₂ were determined at 3T and (c) $R_2^{\text{prime}}$ was calculated for each sample: $R_2^{\text{prime}}$ = R₂* − R₂. An increase in each transverse relaxation rate was observed after iron supplementation, consistent with active iron import in P19 cells. Within 4 hours of the withdrawal of extracellular iron supplement, the signal returned to baseline, consistent with an increase in iron export protein. This finding substantiates dynamic iron regulation in P19 cells. Data are the mean ± SEM (*p < 0.05; **p < 0.01; ***p < 0.001; −Fe, n = 4; +Fe, n = 9; 1h-Fe, n = 3; 2h-Fe, n = 3; 4h-Fe, n = 3; 24h-Fe, n = 9).