この研究は、マイクロ波による体温変化および心血管系変化に対するケタミン麻酔および軽度拘束の影響を比較するため、16匹のフィッシャー344ラットを用い、1）無麻酔・拘束、2）ケタミン麻酔（150 mg / kg体重）の２つの状態で、動物をH方向に向け、遠方界の連続波2.8GHzマイクロ波ばく露を与えた。電力密度60mW / cm 2（全身平均比吸収率14.4W / kg）のばく露で、結腸温度を38.5℃から39.5℃まで周期的に上昇させた。結腸および皮下の温度、大動脈血圧、心拍数を連続的に監視した。その結果、結腸温度の1℃上昇に必要な時間は、麻酔状態の方が有意に長かった；しかし、ベースラインに戻るまでの時間は、両方の状態で同時であった；心拍数および血圧は、無麻酔状態ではばく露中に有意に増加したが、麻酔状態では実質的に変化しなかった；ばく露中の皮下温度上昇は麻酔状態の方が有意に大きかった、と報告している。
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To compare the effects of ketamine anesthesia and mild restraint on microwave-induced thermal and cardiovascular changes, rats were irradiated in two states: 1) unanesthetized, restrained, and 2) ketamine-anesthetized (150 mg/kg).
|ばく露時間||intermittent, see add. information|
|Distance between exposed object and exposure source||150 cm|
|チャンバの詳細||The Eccosorb RF-shielded anechoic chamber was maintained at 27 ± 0.5°C and 20 ± 5% humidity.|
|ばく露装置の詳細||A rat was restrained in a vented Plexiglas cage and placed within the exposure chamber on a stand made of 2-inch thick high density Styrofoam. The rat was positioned along the boresight and exposed in H-orientation (left lateral exposure, long axis of the body parallel to the magnetic field).|
|Additional information||The exposure was interrupted when the colonic temperature had increased from 37.8 ± 0.2°C to 39.5°C, and it was resumed when the temperature had returned to 38.5°C. This procedure was repeated for three cycles after which anaesthesia was provided by an i.m. injection of ketamine. After 10 to 15 min and the start sequence, three additional cycles were completed. Four animal carcasses were irradiated for one additional cycle immediately after euthanasia. The rise and recovery times were 4.1 ± 0.2 min and 12.7 ± 0.9 min for unanaesthetized animals, 7.1 ± 0.4 min and 14.3 ± 0.7 min for anaesthetized animals, and 10.6 ± 1.0 min and 10.7 ± 0.1 min for dead animals, respectively.|
The time required for colonic temperature to increase 1°C was significantly longer in the anesthetized animals; however, the time to return to baseline was similar under both conditions. Heart rate and blood pressure significantly increased during exposure in the unanesthetized state, but remained virtually unchanged in the anesthetized state. The subcutaneous temperature increase during irradiation was significantly greater in the anesthetized state.
The differences in responses of anesthetized and mildly restrained rats should be considered when conducting studies on thermoregulatory responses to microwave exposure.