Effects of a moderate-intensity static magnetic field and adriamycin on K562 cells

The aim of this study was to investigate whether a moderate-intensity static magnetic field (SMF) can enhance the killing effect of adriamycin (ADM) on K562 cells, and to explore the effects of SMF combined with ADM on K562 cells. We analyzed the metabolic activity of cells, cell cycle distribution, DNA damage, change in cell ultrastructure, and P-glycoprotein (P-gp) expression after K562 cells were exposed continuously to a uniform 8.8 mT SMF for 12 h, with or without ADM. Our results showed that the SMF combined with ADM (25 ng/ml) significantly inhibited the metabolic activity of K562 cells (P < 0.05), while neither ADM nor the SMF alone affected the metabolic activity of these cells. Cell ultrastructure was altered in the SMF + ADM group. For example, cell membrane was depressed, some protuberances were observable, and vacuoles in the cytoplasm became larger. Cells were arrested at the G2/M phase and DNA damage increased after cells were treated with the SMF plus ADM. ADM also induced the P-gp expression. In contrast, in the SMF group and SMF + ADM group, the P-gp expression was decreased compared with the ADM group. Taken together, our results showed that the 8.8 mT SMF enhanced the cytotoxicity potency of ADM on K562 cells, and the decrease in P-gp expression may be one reason underlying this effect.

Dopamine release rather than content in the caudate putamen is associated with behavioral changes in the iron rat model of Parkinson's disease

The effects of intranigral iron injection on dopamine (DA) release and content in the caudate putamen (CPu) and their relationship to DA-related behavioral response were investigated in rats. Different concentrations of FeCl(3) (10, 20, and 40 microg) and saline were injected separately into the left substantia nigra. In some experiments, rats were pretreated with desferrioxamine or saline before iron injection. After 3 weeks, changes in behavioral response, DA release, and DA content in the CPu were determined. In all iron injection groups (10, 20, and 40 microg), DA content in the lesioned side of the brain was significantly decreased, showing a significant linear correlation (R(2) = 0.981, P = 0.01), and DA turnover ratio significantly increased (both P = 0.01, 0.01 and 0.001 vs unlesioned sides, respectively). However, injection dosages of 10 or 20 microg of iron did not lead to significant changes in DA release in the CPu or in behavioral response. At the 40-microg dosage, it was found that DA release in the lesioned side and rearing activity both were significantly reduced (all P = 0.01 vs unlesioned side or control) and apomorphine-induced rotation was observed. Pretreatment with desferrioxamine significantly inhibited the effect of iron on DA release and content. These results demonstrate that iron injection can damage dopaminergic neurons and suggest that DA release, rather than DA content, in the CPu is associated with DA-related behavioral changes in this PD model.