A role for the magnetic field in the radiation-induced efflux of calcium ions from brain tissue in vitro

Bioelectromagnetics · 1985 · Mixed · Low evidence

← Research stream

MixedLow evidencePaper 6674

Study snapshot

PublicationBioelectromagnetics · 1985

Study typein_vitro

Reported directionMixed

Evidence ratingLow

Abstract

Two independent laboratories have demonstrated that electromagnetic radiation at specific frequencies can cause a change in the efflux of calcium ions from brain tissue in vitro. In a local geomagnetic field (LGF) at a density of 38 microTesla (microT), 15- and 45-Hz electromagnetic signals (40 Vp-p/m in air) have been shown to induce a change in the efflux of calcium ions from the exposed tissues, whereas 1- and 30-Hz signals do not. We now show that the effective 15-Hz signal can be rendered ineffective when the LGF is reduced to 19 microT with Helmholtz coils. In addition, the ineffective 30-Hz signal becomes effective when the LGF is changed to +/- 25.3 microT or to +/- 76 microT. These results demonstrate that the net intensity of the LGF is an important variable. The results appear to describe a resonance-like relationship in which the frequency of the electromagnetic field that can induce a change in efflux is proportional to a product of LGF density and an index, 2n + 1, where n = 0,1. These phenomenological findings may provide a basis for evaluating the apparent lack of reproducibility of biological effects caused by low-intensity extremely-low-frequency (ELF) electromagnetic signals. In future investigations of this phenomenon, the LGF vector should be explicitly described. If the underlying mechanism involves a general property of tissue, then research conducted in the ambient electromagnetic environment (50/60 Hz) may be subjected to unnoticed and uncontrolled influences, depending on the density of the LGF.

Machine Enhanced Logic

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 directionmixed

PopulationBrain tissue (in vitro)

Sample sizeNot supplied

ExposureELF

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

In a local geomagnetic field (LGF) of 38 microT, 15- and 45-Hz electromagnetic signals (40 Vp-p/m in air) were reported to induce a change in calcium ion efflux from brain tissue in vitro, while 1- and 30-Hz signals did not. Reducing the LGF to 19 microT rendered the 15-Hz signal ineffective, and changing the LGF to +/-25.3 microT or +/-76 microT made the previously ineffective 30-Hz signal effective, suggesting LGF intensity modifies the frequency-dependent effect.

Outcomes measured

Efflux of calcium ions from brain tissue

Limitations

Sample size not reported in abstract
Exposure duration not reported in abstract
Outcome described as a change in efflux without direction/magnitude details in abstract
In vitro findings; generalizability to in vivo/humans not addressed in abstract

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": "ELF",
    "source": "other",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": "Brain tissue (in vitro)",
  "sample_size": null,
  "outcomes": [
    "Efflux of calcium ions from brain tissue"
  ],
  "main_findings": "In a local geomagnetic field (LGF) of 38 microT, 15- and 45-Hz electromagnetic signals (40 Vp-p/m in air) were reported to induce a change in calcium ion efflux from brain tissue in vitro, while 1- and 30-Hz signals did not. Reducing the LGF to 19 microT rendered the 15-Hz signal ineffective, and changing the LGF to +/-25.3 microT or +/-76 microT made the previously ineffective 30-Hz signal effective, suggesting LGF intensity modifies the frequency-dependent effect.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in abstract",
    "Exposure duration not reported in abstract",
    "Outcome described as a change in efflux without direction/magnitude details in abstract",
    "In vitro findings; generalizability to in vivo/humans not addressed in abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "extremely-low-frequency",
    "ELF",
    "geomagnetic field",
    "local geomagnetic field",
    "Helmholtz coils",
    "calcium efflux",
    "brain tissue",
    "frequency-specific effects",
    "resonance-like relationship"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.2,
      "reason": "Mentions ambient 50/60 Hz environment as a potential uncontrolled influence, though study is in vitro and not explicitly occupational."
    }
  ]
}

AI can be wrong. Always verify against the paper.

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: 10.1002/bem.2250060402
PubMed: 3836676

Read the original paper →

Related papers

← Back to the Research Library