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

[幹細胞由来神経細胞内のカルシウム動態に対する無線周波電磁界ばく露の非熱的影響:カルシウム経路の説明] med./bio.

Nonthermal effects of radiofrequency-field exposure on calcium dynamics in stem cell-derived neuronal cells: elucidation of calcium pathways.

掲載誌: Radiat Res 2008; 169 (3): 319-329

この研究は、マウス胎児幹細胞株から分化した神経細胞に対する700-1100 MHz無線周波RF電磁界非熱的な影響として、Caイオンスパイク(Caイオン流入により発生する活動電位)およびCaイオン動態の変化を調べた。その結果、無ばく露対照群では、60%の細胞において60分間に1細胞当たり5回の自発的スパイクが観察されたのに対し、ばく露群(800 MHz、0.5 W/kg)ではスパイクが15.7±0.8回と有意に増加した;スパイク頻度の増加は周波数に依存し、SAR(0.5-5 W/kg)には依らなかった;薬物を利用した実験で、N型CaイオンチャネルとホスフォリパーゼC酵素がこのスパイク増加に介在することが示された、などを報告している。

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研究目的(著者による)

This study was performed to examine nonthermal effects of radiofrequency-field exposure on calcium dynamics in murine stem cell-derived neuronal cells.

詳細情報

An undifferentiated neuronal stem cell of the mouse was selected as it can be easily differentiated into neuronal cells using a known combination of biochemical factors. Furthermore some ion channels are not expressed on the stem cells in undifferentiated state until they undergo neurodifferentiation (e.g. N-type Ca2+ channel, a voltage-dependent calcium channel of the cell membrane). To elucidate the possible Ca2+ influx/efflux pathways the cells were treated with pharmacological inhibitors (amongst others nifedipine, ω-conotoxin: N-type Ca2+ channel blocker, thapsigargin: Ca2+ ATPase inhibitor).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 700–1,100 MHz
ばく露時間: continuous for 60 min
  • SAR: 0.5 W/kg
ばく露2: 800 MHz
ばく露時間: continuous for 60 min

ばく露1

主たる特性
周波数 700–1,100 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 60 min
Additional information 700, 750, 800, 850, 900, 1000, and 1100 MHz
ばく露装置
ばく露の発生源/構造
  • custom-built frequency-tuneable exposure applicator [Pickard et al., 2006]
チャンバの詳細 The applicator was constructed of brass with four pairs of "windows" allowing real-time optical imaging when placed on a microscope stage. An insulating well provided a buffer solution for the seeded cells.
Sham exposure A sham exposure was conducted.
Additional information The differentiated cells were plated on to 24 x 30 mm glass cover slips and cultured with serum-free neurobasal medium for 48 to 60 h before experiments. All experiments were conducted at room temperature of 24-26°C.
パラメータ
測定量 種別 Method Mass 備考
SAR 0.5 W/kg - 計算値 - -

ばく露2

主たる特性
周波数 800 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 60 min
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.
パラメータ
測定量 種別 Method Mass 備考
SAR 0.5 W/kg - 計算値 - -
SAR 1.1 W/kg - 計算値 - -
SAR 5 W/kg - 計算値 - -
SAR 50 W/kg - 計算値 - -

Reference articles

  • Pickard WF et al. (2006): [細胞の同時照射および高分解能非摂動光学顕微鏡法で用いるUHF照射装置の電磁的および熱的特性]

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)

The exposure to radiofrequency irradiation was found to significantly increase the number of Ca2+ spikes, especially in differentiated neuronal cells (maximal number of Ca2+ spikes at a frequency of about 800 MHz). The increase in the Ca2+ spiking activities was dependent on the frequency but not on the specific absortpion rate between 0.5 to 5 W/kg. A statistical significant reduction in the number of Ca2+ spikes was observed at the 50 W/kg specific absorption rate.
No Ca2+ spikes were observed either in control cells or in the exposed cells in the absence of extracelllular Ca2+. This indicates a critical role of Ca2+ influx across the cell membrane. Using pharmacological inhibitors, it was found that both the N-type Ca2+ channels and phospholipase C enzymes appear to be involved in mediating increased Ca2+ spiking.

研究の種別:

研究助成

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