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Abstract
The effects of extremely low frequency electromagnetic fields (EMF) on intracellular Ca2+ mobilization and cellular function in RBL 2H3 cells were investigated. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not produce any cytotoxic effects in RBL 2H3 cells. Melittin, ionomycin and thapsigargin each dose-dependently increased the intracellular Ca2+ concentration. The increase of intracellular Ca2+ induced by these three agents was not affected by exposure to EMF (60 Hz, 1 mT) for 4 or 16 h in RBL 2H3 cells. To investigate the effect of EMF on exocytosis, we measured beta-hexosaminidase release in RBL 2H3 cells. Basal release of beta-hexosaminidase was 12.3±2.3% in RBL 2H3 cells. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not affect the basal or 1μM melittin-induced beta-hexosaminidase release in RBL 2H3 cells. This study suggests that exposure to EMF (60 Hz, 0.1 or 1 mT), which is the limit of occupational exposure, has no influence on intracellular Ca2+ mobilization and cellular function in RBL 2H3 cells.
References
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Fig. 1.
The effect of EMF on cell viability of RBL 2H3 cells. The cells were exposed to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h and viability was measured with MTT assay. Results are indicated in mean±S.D. from four separate experiments.
Fig. 2.
The effect of EMF on the intracellular Ca2+ mobilization induced by melittin in RBL 2H3 cells. Intracellular Ca2+ mobilization induced by melittin was measured with Quanta Master in Fura-2AM-loaded RBL 2H3 cells. Melittin dose-dependently increased intracellular Ca2+ mobilization (A) and 0.5μM melittin-induced intracellular Ca2+ mobilization was not affected by EMF (60 Hz, 1 mT) for 4 or 16 h (B). Results are the representative data of four separate experiments.
Fig. 3.
The effect of EMF on intracellular Ca2+ mobilization induced by ionomycin in RBL 2H3 cells. Ionomycin dose-dependently increased intracellular Ca2+ mobilization (A) and 10 nM ionomycin-induced intracellular Ca2+ mobilization was not affected by EMF (60 Hz, 1 mT) for 4 or 16 h (B). Results are the representative data of four separate experiments.
Fig. 4.
The effect of EMF on intracellular Ca2+ mobilization induced by thapsigargin in RBL 2H3 cells. Thapsigargin dose-dependently increased intracellular Ca2+ mobilization (A) and 100 nM thapsigargin-induced intracellular Ca2+ mobilization was not affected by EMF (60 Hz, 1 mT) for 4 or 16 h (B). Results are the representative data of four separate experiments.
Fig. 5.
The effect of EMF on basal (A) and 1μM melittin-induced beta-hexosaminidase release (B) in RBL 2H3 cells. Both basal and 1μM melittin-induced beta-hexosaminidase release were not affected by exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. Results indicate mean±S.D. from four separate experiments.
Table 1.
Dose-response of beta-hexosaminidase release by melittin, ionomycin and thapsigargin in RBL 2H3 cells
| Groups | Concentrations | % Release |
|---|---|---|
| Control | 14.8±1.6 | |
| Melittin | 0.1 μM | 18.3±1.2∗ |
| 0.5 μM | 28.8±4.1∗ | |
| 1.0 μM | 34.9±6.8∗ | |
| Ionomycin | 1 nM | 13.1±2.1 |
| 10 nM | 14.5±3.6 | |
| 100 nM | 15.2±1.7 | |
| Thapsigargin | 10 nM | 13.5±0.7 |
| 100 nM | 14.3±1.1 | |
| 1000 nM | 16.0±2.3 |
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