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

[パルス高周波電磁界にばく露した単離心筋細胞でのカルシウム恒常性] med./bio.

Calcium homeostasis of isolated heart muscle cells exposed to pulsed high-frequency electromagnetic fields

著者: Wolke S, Neibig U, Elsner R, Gollnick F, Meyer R
掲載誌: Bioelectromagnetics 1996; 17 (2): 144-153
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この研究は、モルモットから単離された心室心筋細胞において、パルス化高周波電磁界ばく露中の細胞内カルシウム濃度（[Ca（2 +）] i）を測定した。高周波電磁界ばく露にはTEMセルを用い、電磁界下での細胞の顕微鏡観察が可能となるように設計された。 [Ca（2 +）] iは、fura-2蛍光法を用い、デジタル画像分析で測定した。搬送周波数および方形波パルス変調パターンの両方を変化させた（搬送周波数900,1300および1,800MHzでの変調パターンは217Hzパルス変調かつデューティサイクル14％、900MHzでの変調パターンは、連続波、16Hzおよび50Hz変調でデューティ・サイクル50%、30KHz変調でデューティ・サイクル80％）。培養液でのSAR値は1mW / kgのオーダー。実験は、500秒間の擬似ばく露、続いて500秒間の高周波ばく露、最後に高周波なしでの化学的刺激の３段階で実施された。化学的刺激（K +脱分極）は、細胞の生存能力を見るためのものである。その結果、擬似ばく露と高周波ばく露との間に有意差は見られなかった；例外は、900MHz / 50Hzの場合に非常に小さいが統計的に有意な差が検出されたことであるが、このわずかな差は、ばく露に関連する影響とはみなされなかった、と報告している。

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研究目的（著者による）

To investigate possible non-thermal effects of GSM exposure characteristics on intracellular calcium homeostasis in isolated cardiac muscle cells of guinea pigs.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 900 MHz
Modulation type: CW
ばく露時間: continuous for 500 s
  • SAR: 59 mW/kg mean (also peak value)
ばく露2: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 500 s
  • SAR: 29 mW/kg mean
  • SAR: 57 mW/kg peak
ばく露3: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 500 s
  • SAR: 30 mW/kg mean
  • SAR: 59 mW/kg peak
ばく露4: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 500 s
  • SAR: 15 mW/kg mean
  • SAR: 123 mW/kg peak
ばく露5: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 500 s
  • SAR: 37 mW/kg mean
  • SAR: 47 mW/kg peak
ばく露6: 1,300 MHz
Modulation type: pulsed
ばく露時間: continuous for 500 s
  • SAR: 12 mW/kg mean
  • SAR: 99 mW/kg peak
ばく露7: 1,800 MHz
Modulation type: pulsed
ばく露時間: continuous for 500 s
  • SAR: 9 mW/kg mean
  • SAR: 69 mW/kg peak
ばく露8: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 120 min
  • SAR: 15 mW/kg mean
  • SAR: 123 mW/kg peak

General information

The experimental schedule varied carrier frequency (900, 1300, and 1800 MHz), modulation frequency (0, 16, 50, 217 Hz, and 30 kHz at 900 MHz), and membrane potential. The experiments included sham runs with the same handling and duration.

ばく露1

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 500 s
Modulation
Modulation type CW
ばく露装置
ばく露の発生源／構造
  • TEMセル
  • cubic with 7 cm edge length, signal generator
チャンバの詳細 The TEM cell was mounted on the object stage of the inverted microscope and contained an open 10-mm experimental chamber for holding the sample. The bottom of this chamber consisted of a glass coverslip and a 1-mm mesh made of 0.05-mm wire and provided shielding while allowing optical observation.
ばく露装置の詳細 The sample volume (200 µl of cell suspension) in the Plexiglas chamber was maintained at 37 ± 0.5 °C by perfusion of the preheated solution and an additional heating fluid running through a circular channel around the sample volume.
Sham exposure A sham exposure was conducted.
Additional information An experimental run consisted of three phases each lasting 500 s. The first phase without any exposure was followed by field exposure. During the third phase a chemical stimulation (K+-depolarization) was performed indicating the viability of the cells which served as positive control.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 59 mW/kg mean 測定値および計算値 - also peak value
測定および計算の詳細

The SAR values achieved were determined by combined measurements and calculations. Field distribution and SAR for 1 W were calculated first. Then the input power to the TEM cell was measured for each applied signal using a bolometer. Finally, the actual SAR values were obtained by multiplication. The SAR values calculated on this basis were only spatial mean values within the solution. The metal mesh, however, created local field inhomogeneities at the level of the cells since the field lines converged towards the wires of the mesh. Calculations on this showed that local SAR values varied by one order of magnitude (or a factor of 3) depending on the position of an individual cell. One millimeter above the wire mesh, the field distribution was even.

ばく露2

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 500 s
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 50 %
Repetition frequency 16 Hz
Pulse type rectangular
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 値 種別 Method Mass 備考
SAR 29 mW/kg mean 測定値および計算値 - -
SAR 57 mW/kg peak 測定値および計算値 - -

ばく露3

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 500 s
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 50 %
Repetition frequency 50 Hz
Pulse type rectangular
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 値 種別 Method Mass 備考
SAR 30 mW/kg mean 測定値および計算値 - -
SAR 59 mW/kg peak 測定値および計算値 - -

ばく露4

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 500 s
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 14 %
Repetition frequency 217 Hz
Pulse type rectangular
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
Additional information In one set of experiments, the membrane potential of the cells was adjusted to different values (-80 mV, -50, -30, and 0 mV). In the third phase, the membrane potential of the depolarized cells was repolarized to -80 mV. This set also included sham runs at each membrane potential.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 15 mW/kg mean 測定値および計算値 - -
SAR 123 mW/kg peak 測定値および計算値 - -

ばく露5

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 500 s
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 80 %
Repetition frequency 30 kHz
Pulse type rectangular
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 値 種別 Method Mass 備考
SAR 37 mW/kg mean 測定値および計算値 - -
SAR 47 mW/kg peak 測定値および計算値 - -

ばく露6

主たる特性
周波数 1,300 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 500 s
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 14 %
Repetition frequency 217 Hz
Pulse type rectangular
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 値 種別 Method Mass 備考
SAR 12 mW/kg mean 測定値および計算値 - -
SAR 99 mW/kg peak 測定値および計算値 - -

ばく露7

主たる特性
周波数 1,800 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 500 s
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 14 %
Repetition frequency 217 Hz
Pulse type rectangular
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 値 種別 Method Mass 備考
SAR 9 mW/kg mean 測定値および計算値 - -
SAR 69 mW/kg peak 測定値および計算値 - -

ばく露8

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 120 min
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 14 %
Repetition frequency 217 Hz
Pulse type rectangular
ばく露装置
ばく露の発生源／構造
  • E1と同じ装置
Sham exposure A sham exposure was conducted.
Additional information In a third set of experiments, long-term exposures were tested. The first phase (without field) lasted 5 min and was followed by 120 min of exposure and 25 min of chemical stimulation (positive control).
パラメータ
測定量 値 種別 Method Mass 備考
SAR 15 mW/kg mean 測定値および計算値 - -
SAR 123 mW/kg peak 測定値および計算値 - -

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:
  • ばく露中

研究の主なアウトカム（著者による）

No significant differences between sham exposure and high-frequency field exposure were found, exept one very small in the case of the 900 MHz (50Hz modutation) exposure. According to the results of this study an influence of pulsed high-frequency fields at GSM range on the intracellular calcium level in isolated cardiac muscle cells is not entirely excluded. However, such influences are very unlikely.

研究の種別:

研究助成

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