Microwave influence on the isolated heart function: II. Combined effect of radiation and some drugs.

Bioelectromagnetics · 1995 · Mixed · Low evidence

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MixedLow evidencePaper 6320

Study snapshot

PublicationBioelectromagnetics · 1995

Study typeanimal

Reported directionMixed

Evidence ratingLow

Abstract

The combined effects of microwave radiation and some drugs were studied in an isolated frog auricle preparation. The experiments established that exposure to pulse-modulated 915 MHz microwaves for up to 40 min had no effect on either the rate or the amplitude of spontaneous auricle twitches, unless the average absorbed power was high enough to produce preparation heating. Treatment of the preparation with saline containing (0.6-3.0) 10(-5) M of propranolol or (0.5-1.5) 10(-7) M of atropine altered neither its pacemaker nor its contractile functions; these drugs also had no effect when they were combined with nonthermal microwave irradiation. Caffeine (1 mM) strongly increased the average heart power, which was calculated as the product of twitch rate and amplitude. The caffeine effect appeared to be significantly augmented (by about 15%, P < 0.02) under exposure to burst-type pulsed microwaves (pulse width, 1.5 msec; pause, 2.5 msec; 8 pulses/burst, 16 bursts/s; average SAR, 8-10 W/kg). By itself, this modulation was not effective; the heating of the preparation and saline during exposure was approximately 0.1 degrees C, which could not account for the detected changes. The experimental results demonstrate that caffeine treatment increases the microwave sensitivity of the frog auricle preparation and reveals primarily subthreshold, nonthermal microwave effect.

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 typeanimal

Effect directionmixed

PopulationIsolated frog auricle preparation

Sample sizeNot supplied

Exposuremicrowave · 915 MHz · up to 40 min

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Pulse-modulated 915 MHz microwave exposure for up to 40 min had no effect on twitch rate or amplitude unless absorbed power was high enough to cause heating. Propranolol or atropine alone did not alter pacemaker or contractile function and showed no effect when combined with nonthermal microwave irradiation. Caffeine (1 mM) increased average heart power, and this effect was augmented by about 15% (P < 0.02) during burst-type pulsed microwave exposure (reported average SAR 8–10 W/kg) with ~0.1°C heating; the modulation alone was not effective.

Outcomes measured

Rate of spontaneous auricle twitches
Amplitude of spontaneous auricle twitches
Average heart power (rate × amplitude)
Preparation heating/temperature change

Limitations

Sample size not reported in abstract
Animal/in vitro isolated organ preparation limits generalizability to humans
Some exposure metrics are incompletely reported for all conditions (e.g., SAR not stated for nonthermal conditions other than burst-type pulsed exposure)

View raw extracted JSON

{
  "study_type": "animal",
  "exposure": {
    "band": "microwave",
    "source": "laboratory exposure (isolated frog auricle preparation)",
    "frequency_mhz": 915,
    "sar_wkg": null,
    "duration": "up to 40 min"
  },
  "population": "Isolated frog auricle preparation",
  "sample_size": null,
  "outcomes": [
    "Rate of spontaneous auricle twitches",
    "Amplitude of spontaneous auricle twitches",
    "Average heart power (rate × amplitude)",
    "Preparation heating/temperature change"
  ],
  "main_findings": "Pulse-modulated 915 MHz microwave exposure for up to 40 min had no effect on twitch rate or amplitude unless absorbed power was high enough to cause heating. Propranolol or atropine alone did not alter pacemaker or contractile function and showed no effect when combined with nonthermal microwave irradiation. Caffeine (1 mM) increased average heart power, and this effect was augmented by about 15% (P < 0.02) during burst-type pulsed microwave exposure (reported average SAR 8–10 W/kg) with ~0.1°C heating; the modulation alone was not effective.",
  "effect_direction": "mixed",
  "limitations": [
    "Sample size not reported in abstract",
    "Animal/in vitro isolated organ preparation limits generalizability to humans",
    "Some exposure metrics are incompletely reported for all conditions (e.g., SAR not stated for nonthermal conditions other than burst-type pulsed exposure)"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "915 MHz",
    "microwave",
    "pulse-modulated",
    "burst-type pulsed",
    "SAR",
    "nonthermal",
    "frog auricle",
    "caffeine",
    "propranolol",
    "atropine",
    "heart power",
    "heating"
  ],
  "suggested_hubs": []
}

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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/bem.2250160407
PubMed: 7488258

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