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[Effects of power frequency magnetic field on gap junction intercellular communication of astrocytes].

Zhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational diseases · 2003 · No effect · Low evidence

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No effectLow evidencePaper 3726

TPA (3 ng/ml for 1 hour) reduced CFIRR compared with control (median 4.53%/min vs 9.74%/min; P<0.005). Exposure to 50 Hz magnetic field at 0.8 or 1.6 mT for 24 hours did not significantly change CFIRR versus control (P>0.05). Pre-exposure to 0.8 or 1.6 mT for…

Study snapshot

PublicationZhonghua lao dong wei sheng zhi ye bing za zhi = Zhonghua laodong weisheng zhiyebing zazhi = Chinese journal of industrial hygiene and occupational diseases · 2003
Study typein_vitro
Reported directionNo effect
Evidence ratingLow

Abstract

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). CONCLUSION: 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.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro
Effect directionno_effect
PopulationAstrocytes (cell culture)
Sample sizeNot supplied
ExposureELF · 0.05 MHz · 24 hours (MF alone); 23 hours MF then 1 hour TPA
Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

TPA (3 ng/ml for 1 hour) reduced CFIRR compared with control (median 4.53%/min vs 9.74%/min; P<0.005). Exposure to 50 Hz magnetic field at 0.8 or 1.6 mT for 24 hours did not significantly change CFIRR versus control (P>0.05). Pre-exposure to 0.8 or 1.6 mT for 23 hours followed by TPA for 1 hour did not significantly differ from TPA alone (P>0.05).

Outcomes measured

  • Gap junction intercellular communication (GJIC)
  • Comparative fluorescence intensity recovery rate (CFIRR) via FRAP

Limitations

  • In vitro study (astrocyte culture), not directly generalizable to humans
  • Sample size and replication details not reported in abstract
  • Only two magnetic flux densities tested (0.8 and 1.6 mT) and one exposure duration
  • Conclusion notes a trend with increasing intensity, but statistical significance for a trend is not provided
View raw extracted JSON
{
  "study_type": "in_vitro",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 0.05,
    "sar_wkg": null,
    "duration": "24 hours (MF alone); 23 hours MF then 1 hour TPA"
  },
  "population": "Astrocytes (cell culture)",
  "sample_size": null,
  "outcomes": [
    "Gap junction intercellular communication (GJIC)",
    "Comparative fluorescence intensity recovery rate (CFIRR) via FRAP"
  ],
  "main_findings": "TPA (3 ng/ml for 1 hour) reduced CFIRR compared with control (median 4.53%/min vs 9.74%/min; P<0.005). Exposure to 50 Hz magnetic field at 0.8 or 1.6 mT for 24 hours did not significantly change CFIRR versus control (P>0.05). Pre-exposure to 0.8 or 1.6 mT for 23 hours followed by TPA for 1 hour did not significantly differ from TPA alone (P>0.05).",
  "effect_direction": "no_effect",
  "limitations": [
    "In vitro study (astrocyte culture), not directly generalizable to humans",
    "Sample size and replication details not reported in abstract",
    "Only two magnetic flux densities tested (0.8 and 1.6 mT) and one exposure duration",
    "Conclusion notes a trend with increasing intensity, but statistical significance for a trend is not provided"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "50 Hz",
    "power frequency magnetic field",
    "ELF magnetic field",
    "astrocytes",
    "gap junction intercellular communication",
    "GJIC",
    "FRAP",
    "CFIRR",
    "TPA",
    "cancer promotion"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.35,
      "reason": "Published in an industrial hygiene/occupational diseases journal and examines power-frequency magnetic field exposure."
    }
  ]
}
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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: Not supplied
PubMed: 14761537

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