Extracellular calcium and microwave enhancement of membrane conductance in snail neurons.

Abstract

Microwave irradiation has been shown to decrease the input resistance of snail neurons. In this study, we examined the role of extracellular calcium in triggering the microwave-induced enhancement of membrane conductance. Two sets of experiments were conducted. In the first set, nerve cells were superfused using Ringer solution with added Cd2+ (0.9 mM) which is a known blocker of calcium channels. In the second set, cells were superfused with low Ca2+ (0.7 mM) Ringer solution. Microwave irradiation was conducted at 2,450 MHz for 30 min with a specific absorption rate of 13 mW/g. It was found that 7 mM to 0.7 mM lowering of Ca2+ in bathing solution as well as blocking of calcium channels in neuronal membrane by means of Cd2+ did not influence the fall in membrane resistance induced by microwave radiation. In fact, the observed changed in membrane resistance in these experiments were nearly equal to those observed for neurons superfused by normal Ringer's. Thus, these results rule out the possible contribution of external Ca2+ in the observed microwave effect. Experiments with high Ca2+ solution also support this conclusion.

AI evidence extraction

Main findings

Microwave irradiation (2450 MHz, 30 min, SAR 13 mW/g) decreased membrane resistance (increased membrane conductance) in snail neurons. Lowering extracellular Ca2+ (7 mM to 0.7 mM) or blocking calcium channels with Cd2+ (0.9 mM) did not change the microwave-induced fall in membrane resistance compared with normal Ringer solution; high Ca2+ experiments were reported as supportive.

Outcomes measured

• membrane conductance
• membrane resistance
• input resistance

Limitations

• Sample size not reported in abstract
• Only snail neurons studied; generalizability to other species or humans not addressed
• Mechanistic inference limited to extracellular Ca2+ manipulation described; other pathways not assessed in abstract

{
    "study_type": "animal",
    "exposure": {
        "band": "microwave",
        "source": null,
        "frequency_mhz": 2450,
        "sar_wkg": 13,
        "duration": "30 min"
    },
    "population": "snail neurons",
    "sample_size": null,
    "outcomes": [
        "membrane conductance",
        "membrane resistance",
        "input resistance"
    ],
    "main_findings": "Microwave irradiation (2450 MHz, 30 min, SAR 13 mW/g) decreased membrane resistance (increased membrane conductance) in snail neurons. Lowering extracellular Ca2+ (7 mM to 0.7 mM) or blocking calcium channels with Cd2+ (0.9 mM) did not change the microwave-induced fall in membrane resistance compared with normal Ringer solution; high Ca2+ experiments were reported as supportive.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in abstract",
        "Only snail neurons studied; generalizability to other species or humans not addressed",
        "Mechanistic inference limited to extracellular Ca2+ manipulation described; other pathways not assessed in abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave irradiation",
        "2450 MHz",
        "specific absorption rate",
        "snail neurons",
        "membrane resistance",
        "membrane conductance",
        "extracellular calcium",
        "Cd2+",
        "calcium channels"
    ],
    "suggested_hubs": []
}

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