Effects of pulsed microwave radiation on the contractile rate of isolated frog hearts.

Abstract

Hearts from 81 frogs were divided into 10 groups and placed individually in a temperature-controlled waveguide filled with Ringer's solution. Hearts of Group A served as controls. Hearts of the other nine groups were treated with pulsed microwaves (2450 MHz, 10 microseconds, 100 pps) that ranged from a specific-absorption rate (SAR) of 2 to 200 W/kg. In several groups, an electrocardiogram was used to synchronize microwave irradiation with the heartbeat. In one group of frog hearts exposed at 200 W/kg, the heart rate slowed down sharply 25 minutes after irradiation, by which time the temperature of the Ringer's solution had risen by 7 degrees C. In another group exposed at 200 W/kg but under constant temperature, the heartbeat almost paralleled that of the control group. Other groups, including exposures of frog hearts to 16 Hz modulated CW or pulsed fields at SARs from 3 mW/kg to 8.55 W/kg, showed no effects of pulsed microwave irradiation on heartbeats; no brachycardia or tachycardia were found at constant temperatures.

AI evidence extraction

Main findings

Across groups exposed to pulsed microwaves at SARs from 3 mW/kg to 8.55 W/kg (and other described conditions), no bradycardia or tachycardia was observed at constant temperatures. At 200 W/kg, one group showed a sharp slowing of heart rate after 25 minutes coinciding with a 7°C rise in solution temperature, while another 200 W/kg group under constant temperature had heartbeats that almost paralleled controls.

Outcomes measured

• Contractile rate/heart rate
• Bradycardia
• Tachycardia
• Temperature change of Ringer's solution

Limitations

• Isolated organ (frog hearts) in a waveguide; findings may not generalize to intact organisms or humans.
• Temperature changes occurred in at least one high-SAR condition, complicating attribution to non-thermal effects.
• Exposure duration details are not fully specified for all groups in the abstract.

Suggested hubs

• rf-microwave-bioeffects (0.9)
  Animal (isolated organ) experiment testing 2450 MHz microwave exposure and cardiac rate outcomes.

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Isolated frog hearts (from 81 frogs)",
    "sample_size": 81,
    "outcomes": [
        "Contractile rate/heart rate",
        "Bradycardia",
        "Tachycardia",
        "Temperature change of Ringer's solution"
    ],
    "main_findings": "Across groups exposed to pulsed microwaves at SARs from 3 mW/kg to 8.55 W/kg (and other described conditions), no bradycardia or tachycardia was observed at constant temperatures. At 200 W/kg, one group showed a sharp slowing of heart rate after 25 minutes coinciding with a 7°C rise in solution temperature, while another 200 W/kg group under constant temperature had heartbeats that almost paralleled controls.",
    "effect_direction": "mixed",
    "limitations": [
        "Isolated organ (frog hearts) in a waveguide; findings may not generalize to intact organisms or humans.",
        "Temperature changes occurred in at least one high-SAR condition, complicating attribution to non-thermal effects.",
        "Exposure duration details are not fully specified for all groups in the abstract."
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "pulsed microwave",
        "2450 MHz",
        "specific absorption rate",
        "SAR",
        "frog heart",
        "heart rate",
        "bradycardia",
        "temperature control",
        "Ringer's solution",
        "ECG synchronization"
    ],
    "suggested_hubs": [
        {
            "slug": "rf-microwave-bioeffects",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Animal (isolated organ) experiment testing 2450 MHz microwave exposure and cardiac rate outcomes."
        }
    ]
}

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