研究のタイプ: 医学／生物学の研究 (experimental study)

[赤血球に対するマイクロ波の熱的および非熱的影響の研究] med./bio.

An investigation of the thermal and athermal effects of microwave irradiation on erythrocytes

著者: Peterson DJ, Partlow LM, Gandhi OP
掲載誌: IEEE Trans Biomed Eng 1979; 26 (7): 428-436
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この研究は、マイクロ波照射法または従来の加熱法のどちらかで加熱されたウサギ赤血球からのヘモグロビン（Hb）およびカリウム（K+）の流出を比較した。全ての実験において、マイクロ波加熱赤血球（RBC）を、インキュベータ調節により同じ温度に温めたRBC、および室温保存のRBCと直接比較した。マイクロ波照射は、2.45 GHzまたは周波数範囲12.5-18 GHz 内で選択された0.5 GHzの掃引周波数帯のいずれかで行われた。試料温度は、液晶光ファイバ温度プローブで連続的にモニタされた。その結果、マイクロ波（2.45 GHz, 10 mW/cm2）または従来の加熱法で、45分間、ウサギRBCの温度を3.7°C上昇させた場合、室温保存のRBCと比較して、上清中へのHbおよびK+の流出に変化はなかった；どちらかの方法でウサギＲＢＣを室温から37°Cまで急速に加温した場合、室温保存のRBCと比較して、HbおよびK+の両方の上清中への流出が有意に増加した；さらにどちらかの方法で41.5°Cまでの加温の場合、37°Cまでの加温に比べ、はるかに多くのＨｂおよびK+が流出された；同じ加温速度で、同じ最終温度まで加温された場合、どちらの加温方法によっても同じ量のHbおよびK+の流出が見られた、と報告している。したがって、上清中へのHbおよびK+の流出は、赤血球膜の安定性および／または透過性への熱的影響に起因すると考えられると結論している。

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研究目的（著者による）

To investigate thermal and athermal effects microwave irradiation on erythrocytes.

詳細情報

Potassium and hemoglobin loss were determined as it indicates altered stability and/or permeability of the erythrocyte membrane.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 2.45 GHz
ばく露時間: continuous for 45 min
  • 電力密度: 10 mW/cm²
  • 電力密度: 30 mW/cm² cf. remarks (to maintain temp at 37°C (30-35 mW/cm²))
  • 電力密度: 43 mW/cm² cf. remarks (to raise temp to 37°C at half the rate)
  • 電力密度: 90 mW/cm² cf. remarks (to raise temp to 37°C (86-90 mW/cm²))
  • 電力密度: 140 mW/cm² cf. remarks (to raise temp to 37°C at twice the rate)
  • 電力密度: 93 mW/cm² cf. remarks (to maintain temp at 41.5°C)
  • 電力密度: 112 mW/cm² cf. remarks (to raise temp to 41.5°C)
ばく露2: 12.5–18 GHz
ばく露時間: continuous for 45 min
  • 電力密度: 31 mW/cm² cf. remarks (to maintain temp at 37°C)
  • 電力密度: 124 mW/cm² cf. remarks (to raise temp to 37°C)

ばく露1

主たる特性
周波数 2.45 GHz
タイプ
  • electromagnetic field
特性
  • far field
ばく露時間 continuous for 45 min
ばく露装置
ばく露の発生源／構造
Distance between exposed object and exposure source 137 cm
ばく露装置の詳細 The suspension was filled in 0.4 ml polypropylene microcentrifuge tubes of 0.4 cm diameter and 4.5 cm length with a 0.05 ml air gap remaining at the top after capping. In the first experiment, sample tubes were placed in a stationary Styrofoam sample holder with the long axis of each tube parallel to the E-field vector. For all further experiments, a rotating sample holder was used to achieve identical exposure of all tubes. They were inserted in radial holes in a Styrofoam disk held in the vertical position by a long Teflon shaft of 2.5 cm diameter turned at 2 rpm by a motor shielded by RF-absorbing material. The vertical rotation (reversed every minute) caused a continuous mixing of the suspension.
Additional information In the first experiment, irradiation was interrupted every 10 min in order to measure the temperature of the samples. In all further experiments, the temperature was continuously monitored using an LCOF probe. The matched thermal profile control samples were heated in a water bath (first experiment) or in a hot air incubator with a rotating sample holder.
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 10 mW/cm² - 測定値 - -
電力密度 30 mW/cm² cf. remarks 測定値 - to maintain temp at 37°C (30-35 mW/cm²)
電力密度 43 mW/cm² cf. remarks 測定値 - to raise temp to 37°C at half the rate
電力密度 90 mW/cm² cf. remarks 測定値 - to raise temp to 37°C (86-90 mW/cm²)
電力密度 140 mW/cm² cf. remarks 測定値 - to raise temp to 37°C at twice the rate
電力密度 93 mW/cm² cf. remarks 測定値 - to maintain temp at 41.5°C
電力密度 112 mW/cm² cf. remarks 測定値 - to raise temp to 41.5°C
Additional parameter details

Samples were either irradiated at 10 mW/cm² reaching a temperature of 28.7°C (i.e. a rise of 3.7°C) or heated up to 37°C or 41.5°C by varying power densities.

測定および計算の詳細

Output power was measured by a power meter for both systems. Power density was measured by a radiation monitor for this system. SAR was determined from the rate of temperature rise using high field intensities and short exposure times.

ばく露2

主たる特性
周波数 12.5–18 GHz
タイプ
  • electromagnetic field
特性
  • far field
ばく露時間 continuous for 45 min
Additional information Frequency was swept: 12.5-13 GHz, 13.5-14 GHz, 14.5-15 GHz, 15.5-16 GHz, 16.5-17 GHz, or 17.5-18 GHz.
ばく露装置
ばく露の発生源／構造
Distance between exposed object and exposure source 10 cm
パラメータ
測定量 値 種別 Method Mass 備考
電力密度 31 mW/cm² cf. remarks 測定値 - to maintain temp at 37°C
電力密度 124 mW/cm² cf. remarks 測定値 - to raise temp to 37°C
測定および計算の詳細

Power density was calculated from the configuration for this system because it could not be measured directly by any available radiation monitor.

ばく露を受けた生物:

方法 影響評価項目／測定パラメータ／方法

研究対象とした生物試料:
調査の時期:
  • ばく露後

研究の主なアウトカム（著者による）

No differences were found between microwave heated or conventionally heated erythrocyte-suspensions. Thus, the found effects should be ascribed only as thermal.

研究の種別:

研究助成

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