[Effects of power frequency magnetic field on gap junction intercellular communication of astrocytes].
OBJECTIVE
In order to explore if power frequency magnetic field (PFMF) can act as cancer promoter or be synergistic with phorbol 12-myristate 13-acetate (TPA) in cancer promotion, the effects of 50 Hz MF on gap junction intercellular communication (GJIC) of astrocytes were observed.


METHODS
Fluorescence redistribution after photobleaching (FRAP) was adopted to observe the recovery of fluorescence intensity in the bleached cells thus to estimate intercellular communication by gap junction. Comparative fluorescence intensity recovery rate (CFIRR) was as evaluation index. The effects of 50 Hz MF alone or with TPA on GJIC of astrocytes were studied.


RESULTS
After 3 ng/ml TPA treatment for 1 hour, M(d) of CFIRR was 4.53%/min, whereas that in the control group was 9.74%/min (H = 12.084, P < 0.005). After exposure to 0.8 and 1.6 mT magnetic field for 24 hours respectively, M(d) of CFIRR was 8.25%/min and 6.68%/min respectively, no significant difference from that of control (H = 32.617, P > 0.05). After exposure to 0.8 and 1.6 mT magnetic field for 23 hours then combined with 3 ng/ml TPA treatment for 1 hour, M(d) of CFIRR was 3.32%/min and 2.85%/min respectively, also no significant difference from that in the group treated with 3 ng/ml TPA alone (H = 2.589, P > 0.05).


CONCLUSIONS
50 Hz MF (within 0 - 1.6 mT) alone could not inhibit GJIC of astrocytes; with TPA, could not enhance the inhibition of TPA on GJIC of astrocytes. But with MF intensity increasing, the inhibition of MF on GJIC showed elevated tendency.
Li
Xiu-zhen
XZ
Pathologic Department, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310009, China.
Zhang
Suo-jiang
SJ
Zhu
Ke-qing
KQ
Zhang
Xin
X
Lu
De-qiang
DQ
D000818:Animals; D001253:Astrocytes / Q000528:radiation effects* / Q000648:ultrastructure; D002450:Cell Communication / Q000528:radiation effects*; D004574:Electromagnetic Fields / Q000009:adverse effects*; D017629:Gap Junctions / Q000528:radiation effects*; D009955:Ornithine Decarboxylase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate