Myocardial function improved by electromagnetic field induction of stress protein hsp70.

Journal of cellular physiology · 2008 · Benefit · Low evidence

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BenefitLow evidencePaper 5015

Rats pre-exposed to a 60 Hz, 8 microT electromagnetic field for 30 minutes showed significant upregulation of the HSP70 gene and increased hsp70 protein levels. EMF pre-conditioning was associated with significant recovery of systolic contractile function aft…

Study snapshot

PublicationJournal of cellular physiology · 2008

Study typeanimal

Reported directionBenefit

Evidence ratingLow

Abstract

Studies on myocardial function have shown that hsp70, stimulated by an increase in temperature, leads to improved survival following ischemia-reperfusion (I-R). Low frequency electromagnetic fields (EMFs) also induce the stress protein hsp70, but without elevating temperature. We have examined the hemodynamic changes in concert with EMF pre-conditioning and the induction of hsp70 to determine whether improved myocardial function occurs following I-R injury in Sprague-Dawley rats. Animals were exposed to EMF (60 Hz, 8 microT) for 30 min prior to I-R. Ischemia was then induced by ligation of left anterior descending coronary artery (LAD) for 30 min, followed by 30 min of reperfusion. Blood and heart tissue levels for hsp70 were determined by Western blot and RNA transcription by rtPCR. Significant upregulation of the HSP70 gene and increased hsp70 levels were measured in response to EMF pre-exposures. Invasive hemodynamics, as measured using a volume conductance catheter, demonstrated significant recovery of systolic contractile function after 30 min of reperfusion following EMF exposure. Additionally, isovolemic relaxation, a measure of ventricular diastolic function, was markedly improved in EMF-treated animals. In conclusion, non-invasive EMF induction of hsp70 preserved myocardial function and has the potential to improve tolerance to ischemic injury.

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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 typeanimal

Effect directionbenefit

PopulationSprague-Dawley rats

Sample sizeNot supplied

ExposureELF · 6e-05 MHz · 30 min prior to ischemia-reperfusion

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Outcomes measured

HSP70 gene expression (RNA transcription by rtPCR)
hsp70 protein levels in blood and heart tissue (Western blot)
Invasive hemodynamics / systolic contractile function after reperfusion
Isovolemic relaxation (ventricular diastolic function) following ischemia-reperfusion

Limitations

Sample size not reported in the provided abstract.
Animal model; generalizability to humans not established in the provided abstract.
Exposure parameters limited to a single frequency/intensity and short pre-conditioning duration in the provided abstract.

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "ELF",
    "source": null,
    "frequency_mhz": 6e-05,
    "sar_wkg": null,
    "duration": "30 min prior to ischemia-reperfusion"
  },
  "population": "Sprague-Dawley rats",
  "sample_size": null,
  "outcomes": [
    "HSP70 gene expression (RNA transcription by rtPCR)",
    "hsp70 protein levels in blood and heart tissue (Western blot)",
    "Invasive hemodynamics / systolic contractile function after reperfusion",
    "Isovolemic relaxation (ventricular diastolic function) following ischemia-reperfusion"
  ],
  "main_findings": "Rats pre-exposed to a 60 Hz, 8 microT electromagnetic field for 30 minutes showed significant upregulation of the HSP70 gene and increased hsp70 protein levels. EMF pre-conditioning was associated with significant recovery of systolic contractile function after 30 minutes of reperfusion and markedly improved isovolemic relaxation compared with controls.",
  "effect_direction": "benefit",
  "limitations": [
    "Sample size not reported in the provided abstract.",
    "Animal model; generalizability to humans not established in the provided abstract.",
    "Exposure parameters limited to a single frequency/intensity and short pre-conditioning duration in the provided abstract."
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ELF-EMF",
    "60 Hz",
    "8 microT",
    "pre-conditioning",
    "ischemia-reperfusion",
    "myocardial function",
    "hemodynamics",
    "HSP70",
    "stress protein",
    "Sprague-Dawley rat",
    "LAD ligation",
    "reperfusion"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.2,
      "reason": "Uses 60 Hz ELF-EMF, a frequency relevant to power-line/occupational contexts, though the study is an animal pre-conditioning experiment rather than an exposure survey."
    }
  ]
}

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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: 10.1002/jcp.21461
PubMed: 18446816

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