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

[Wisterラットのオペラント行動に対する高ピーク電力マイクロ波パルスばく露後の急性影響] med./bio.

Immediate post-exposure effects of high-peak-power microwave pulses on operant behavior of Wistar rats.

掲載誌: Bioelectromagnetics 1991; 12 (3): 183-195

この研究は、Wisterラット行動に対する高電力ピーク値をもつマイクロ波パルスの影響をオペラント実験で調べた。餌を受け取れるレバー押しを訓練された12匹のラットを、オペラント行動の自発頻度の強化スケジュール、すなわち、定率強化(RF)スケジュール、変動間隔(VI)スケジュール、高反応率分化強化(DRL)スケジュールに4匹づつ分けた。一定のベースライン成績を達成させた後、各動物に、1.25GHzマイクロ波(ピーク電力1MW、パルス幅10 μ秒)を10分間照射した。1発のパルスによる全身SAおよび全身SARのピーク値は、2.1 J/kgおよび0.21 MW/kgであり、繰り返しパルス数を調整して、総SA値を0.5、1.5、4.5、14 kJ/kg(対応する全身SARの時間平均は0.84、2.5、7.6、23 W/kg)に設定した。動物の体軸は電界と並行に保持した。その結果、ばく露最大値で直腸温は2.5℃上昇し、ばく露終了後13分間、全てのオペラント行動が見られなかった;反応が再開した時、直腸温上昇は1.1℃またはそれ以下に低下していた、などを報告している。

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研究目的(著者による)

To study behavioral effects of high-peak-power microwave pulses on rats by operant schedules and to test the hypothesis that these microwaves would result in work disruption at all rates of performance. Specifically, it was designed to study conjointly both SA (specific absorption, total doses, kJ/kg) and SAR-dependent effects of such exposure.

詳細情報

Rats that had been trained to press a lever to receive food pellets were assigned randomly in groups to three different schedules of reinforcement (to establish three different response patterns with differential response rates): fixed-ratio schedule, variable interval schedule, and differential-reinforcement-of-low-rates (DRL schedule). The fixed-ratio schedule requires that a set number of responses be made for each reinforcement and typically produces a high rate of responding. The variable interval schedule requires only one response for the delivery of reinforcement after a certain amount of time has elapsed. The DRL schedule requires only one response after delivery of a food pellet, but only if this response is delayed for a predetermined time period.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1.25 GHz
Modulation type: pulsed
ばく露時間: continuous; 10 min
  • SAR: 840 µW/g average over time (whole body) (0.5 kJ/kg corresponding specific absorbion)
ばく露2: 1.25 GHz
Modulation type: pulsed
ばく露時間: continuous; 10 min
  • SAR: 2.5 mW/g average over time (whole body) (1.5 kJ/kg corresponding specific absorbion)
ばく露3: 1.25 GHz
Modulation type: pulsed
ばく露時間: continuous; 10 min
  • SAR: 7.6 mW/g average over time (whole body) (4.5 kJ/kg corresponding specific absorbion)
ばく露4: 1.25 GHz
Modulation type: pulsed
ばく露時間: continuous; 10 min
  • SAR: 23 mW/g average over time (whole body) (14 kJ/kg corresponding specific absorbion)

ばく露1

主たる特性
周波数 1.25 GHz
タイプ
  • electromagnetic field
波形
  • sinusoidal
特性
  • far field
ばく露時間 continuous; 10 min
Modulation
Modulation type pulsed
Pulse width 10 µs
Rise time 5 ns
Additional information

240 pulses

ばく露装置
ばく露の発生源/構造
チャンバの詳細 anechoic chamber; 65° corner reflector; power gain 14.5 db
ばく露装置の詳細 a microwave-transparent animal holder (20 cm x 7 cm x 6.5 cm lxhxw) was used to constrain the animal inorder to keeo its body axis parallel to electric field
パラメータ
測定量 種別 Method Mass 備考
SAR 840 µW/g average over time 計算値 whole body 0.5 kJ/kg corresponding specific absorbion

ばく露2

主たる特性
周波数 1.25 GHz
タイプ
  • electromagnetic field
波形
  • sinusoidal
特性
  • far field
ばく露時間 continuous; 10 min
Modulation
Modulation type pulsed
Pulse width 10 µs
Rise time 5 ns
Additional information

720 pulses

ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
SAR 2.5 mW/g average over time 計算値 whole body 1.5 kJ/kg corresponding specific absorbion

ばく露3

主たる特性
周波数 1.25 GHz
タイプ
  • electromagnetic field
波形
  • sinusoidal
特性
  • far field
ばく露時間 continuous; 10 min
Modulation
Modulation type pulsed
Pulse width 10 µs
Rise time 5 ns
Additional information

2160 pulses

ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
SAR 7.6 mW/g average over time 計算値 whole body 4.5 kJ/kg corresponding specific absorbion

ばく露4

主たる特性
周波数 1.25 GHz
タイプ
  • electromagnetic field
波形
  • sinusoidal
特性
  • far field
ばく露時間 continuous; 10 min
Modulation
Modulation type pulsed
Pulse width 10 µs
Rise time 5 ns
Additional information

6480 pulses

ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
SAR 23 mW/g average over time 計算値 whole body 14 kJ/kg corresponding specific absorbion

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)

Exposures at the highest dose caused an average colonic temperature rise of 2.5°C and these rats failed to respond at all for about 13 minutes after the irradiation. Their colonic temperatures had decreased to 1.1°C, or less, above their pre-exposure (normal) temperature level when the animals began to respond. The fixed-ratio schedule and variable interval schedule rats failed to reach their baseline levels of performance thereafter, while those on the DRL schedule (differential-reinforcement-of-low-rates) schedule displayed variable effects. No behavioral effects were observed at the lower dose levels. The authors concluded that the behavioral perturbations produced by pulsed microwave irradiation were thermal in nature.

研究の種別:

研究助成