Figure 3.

Acute particle-induced changes in intracellular iron (PhenGreen fluorescence) at (A) 18 and (B) 24 h. Doses refer to the administered dose. Error bars indicate the mean ± SEM (n = 4). Cross hatches indicate the addition of 100 μM pyridoxal isonicotinoyl hydrazine (PIH, iron chelator). In Beas2B cells, the majority of iron is sequestered and not catalytically active. PIH, as a chelator, and PhenGreen, as a fluorescent marker, actively target chelatable iron within the cell’s catalytically active labile iron pool,⁵⁶ which is why it had minimal effect on acutely treated Beas2B, with the exception of FeSO4 treatment. F₀/F: the inverse integrated intensity of the fluorescent signal. *p < 0.05 from the same particle treatment without PIH chelation.