Journal List > Korean J Physiol Pharmacol > v.14(6) > 1025714

Song, Kim, Ko, Jeong, Kim, Kim, Hwang, Sohn, Gimm, Myung, and Sim: Effect of Extremely Low Frequency Electromagnetic Fields (EMF) on Phospholipase Activity in the Cultured Cells

Abstract

This study was conducted to investigate the effects of extremely low frequency electromagnetic fields (EMF) on signal pathway in plasma membrane of cultured cells (RAW 264.7 cells and RBL 2H3 cells), by measuring the activity of phospholipase A2 (PLA2), phospholipase C (PLC) and phospholipase D (PLD). The cells were exposed to the EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. The basal and 0.5 μM melittin-induced arachidonic acid release was not affected by EMF in both cells. In cell-free PLA2 assay, we failed to observe the change of cPLA2 and sPLA2 activity. Also both PLC and PLD activities did not show any change in the two cell lines exposed to EMF. This study suggests that the exposure condition of EMF (60 Hz, 0.1 or 1 mT) which is 2.4 fold higher than the limit of occupational exposure does not induce phospholipases-associated signal pathway in RAW 264.7 cells and RBL 2H3 cells.

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Fig. 1.
The changes of basal (A) and 0.5μM melittin-induced [3H]AA release (B) in RAW 264.7 cells. The cells were exposed to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h and were labeled with [3H]AA for 2 h. The radioactivity of released [3H]AA was measured in the presence or absence of 0.5μM melittin. Results are indicated in mean±S.D. from four separate experiments.
kjpp-14-427f1.tif
Fig. 2.
The changes of basal (A) and 0.5μM melittin-induced [3H]AA release (B) in RBL 2H3 cells. The cells were exposed to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h and were labeled with [3H]AA for 2 h. The radioactivity of released [3H]AA was measured in the presence or absence of 0.5μM melittin. Results indicate mean±S.D. from four separate experiments.
kjpp-14-427f2.tif
Fig. 3.
Cell-derived PLA2 activity in the presence of 5 mM CaCl2. PLA2 (25μg protein) derived from RAW 264.7 cells and RBL 2H3 cells was incubated with 1-palmitoyl-2-[14C]arachidonyl phosphatidylcholine in the presence of 10μM AACOCF3 (cPLA2 inhibitor) or 1 mM DTT (sPLA2 inhibitor) and in the absence of CaCl2. Results indicate mean±S.D. from four separate experiments. Significantly different from Control (p<0.05).
kjpp-14-427f3.tif
Fig. 4.
Effect of EMF on cell-derived cPLA2 activity. Cell-derived cPLA2 was obtained from the RAW 264.7 cells (A) and RBL 2H3 cells (B) exposed to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. cPLA2 (25μg protein) was incubated with 1-palmitoyl-2-[14C]arachidonyl phosphatidylcholine in the presence of 5 mM CaCl2 and 1 mM DTT. Results indicate mean±S.D. from four separate experiments.
kjpp-14-427f4.tif
Fig. 5.
Effect of EMF on cell-derived sPLA2 activity. Cell-derived sPLA2 was obtained from the RAW 264.7 cells (A) and RBL 2H3 cells (B) exposed to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. sPLA2 (100μg protein) was incubated with 10-pyren phosphatidylcholine. Results indicate mean±S.D. from four separate experiments.
kjpp-14-427f5.tif
Fig. 6.
Effect of EMF on cell-derived PLC activity. Cell-derived PLC was obtained from the RAW 264.7 cells (A) and RBL 2H3 cells (B) exposed to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. PLC (25μg protein) was incubated with [3H]phosphatidylinositol. Results indicate mean±S.D. from four separate experiments.
kjpp-14-427f6.tif
Fig. 7.
Effect of EMF on PLD activity. RAW 264.7 cells (A) and RBL 2H3 cells (B) were exposed to EMF (60 Hz, 1 mT) for 4 or 16 hand were labeled with [3H]oleic acid, for 3 h. The radioactivity of [3H]phosphatidylethanol produced by PLD was measured in the presence or absence of 1μM PMA. Results indicate mean±S.D. from four separate experiment.
kjpp-14-427f7.tif
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