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

[ラットの700 MHz無線周波照射中の界の方向による影響] med./bio.

Effects of field orientation during 700-MHz radiofrequency irradiation of rats.

掲載誌: Physiol Chem Phys Med NMR 1989; 21 (1): 65-72

この研究は、ケタミン麻酔下のSprague-Dawleyラットに、E方向あるいはH方向の遠方界の700MHz連続波無線周波放射(RFR)のばく曝を与え、その影響を調べた。全身平均比吸収率(SAR)は、EおよびH方向においてそれぞれ、9.2および13.0 W / kgであった。この全身平均比吸収率(SAR)は、ほぼ同等の結腸比加熱率(SHR)を生じる。結腸温度を1℃(38.5から39.5℃へ)上昇させるように反復的にばく露を行なった。鼓膜、尾、左右(RFR源に面する方向と遠ざかる方向)の皮下温度、結腸温度、動脈血圧、および呼吸数を連続的に記録した。その結果、同等の結腸SHRおよびE方向での平均SARの低値にも拘らず、右皮下、鼓膜、および尾のSARs、SHRsおよび絶対温度上昇は、H方向よりもE方向の場合に有意に大きかった;全てのモニター部位での温度低下速度も、H方向よりもE方向の場合に有意に大きかった;心拍数平均動脈血圧ばく露中に有意に増加したが、向きによる違いはなかった; H方向の場合、ばく露中に呼吸数が有意に増加したが、E方向では増加しなかった;以上から、共振周波数ばく露においては、EおよびH方向によって、熱吸収分布パターンに差が生じることが示された、と報告している。

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研究目的(著者による)

To determine if the E-orientation (long axis of body parallel to electric field) versus H-orientation (long axis parallel to magnetic field) effects upon thermal, cardiovascular, and respiratory changes noted at 2450 MHz (see publication 2239) were also present at the resonant frequency of 700 MHz.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 700 MHz
Modulation type: CW
ばく露時間: intermittend 7.2 min +/ 0.5 min exposure - 10.6 min +/- 0.5 min recovery time
  • SAR: 9.2 mW/g mean (whole body)
ばく露2: 700 MHz
Modulation type: CW
ばく露時間: intermittend 7.2 min +/ 0.5 min exposure - 10.6 min +/- 0.5 min recovery time
  • SAR: 13 mW/g mean (whole body)

General information

*The exposure was discontinued when the colonic temperature increased to 39.5°C and it was initiated again when the temperature returned to 38.5°C. This procedure was continued for 3 cycles

ばく露1

主たる特性
周波数 700 MHz
タイプ
  • electromagnetic field
特性
  • far field
偏波
  • linear
ばく露時間 intermittend 7.2 min +/ 0.5 min exposure - 10.6 min +/- 0.5 min recovery time
Additional information Animals were exposed in E.orientation (long axis parallel to electric field)
Modulation
Modulation type CW
ばく露装置
ばく露の発生源/構造
  • 90° corner reflector antenna
Distance between exposed object and exposure source 1 m
チャンバの詳細 Eccosorb RF-shield anechoic chamber
ばく露装置の詳細 Animals placed on a holder which consisted of seven 0.5 cm (O.D) Plexiglas rods mounted in a semicircular pattern on 4 cm x 6 cm Plexiglas plates (0.5 cm thick)
パラメータ
測定量 種別 Method Mass 備考
SAR 9.2 mW/g mean 計算値 whole body -

ばく露2

主たる特性
周波数 700 MHz
タイプ
  • electromagnetic field
特性
  • far field
偏波
  • linear
ばく露時間 intermittend 7.2 min +/ 0.5 min exposure - 10.6 min +/- 0.5 min recovery time
Additional information Animals were exposed in H.orientation (long axis parallel to magnetic field)
Modulation
Modulation type CW
ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
Distance between exposed object and exposure source 1 m
パラメータ
測定量 種別 Method Mass 備考
SAR 13 mW/g mean 計算値 whole body -

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:
研究対象とした臓器系:
調査の時期:
  • ばく露中

研究の主なアウトカム(著者による)

In spite of equivalent colonic specific heating rates (SHR) and the reduced E-orientation average SAR, the right subcutaneous, tympanic, and tail SARs, SHRs and absolute temperature increases were significantly greater in E- than in H-orientation. The cooling rate of the animals at all monitoring sites was also significantly greater in E- than in H-orientation. Heart rate and mean arterial blood pressure significantly increased during exposure; however, alterations between orientations were not different. Respiratory rate significantly increased during exposure in H-, but not in E-orientation.
These findings suggest that during resonant frequency irradiation, differences occur in the pattern of heat deposition between E- and H-orientation exposure. When compared with previous studies performed at supraresonant frequencies (e.g. publication 2239), the lower level of cardiovascular change in this investigation was probably related to the lower periphery-to-core thermal gradient.

研究の種別:

研究助成

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