Intracellular Ca Mobilization and Beta-hexosaminidase Release Are Not Influenced by 60 Hz-electromagnetic Fields (EMF) in RBL 2H3 Cells

Abstract

The effects of extremely low frequency electromagnetic fields (EMF) on intracellular Ca(2+) 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 Ca(2+) concentration. The increase of intracellular Ca(2+) 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 1 µM 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 Ca(2+) mobilization and cellular function in RBL 2H3 cells.

Keywords: Beta-hexosaminidase; Ca2+ mobilization; EMF; Exocytosis.

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 0.5 µM 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 ionomycininduced 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 1 µM melittin-induced beta-hexosaminidase release (B) in RBL 2H3 cells. Both basal and 1 µM 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.