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

[パルスラジオ周波数電磁界にばく露された単離心筋細胞の膜電位と電流] med./bio.

Membrane potential and currents of isolated heart muscle cells exposed to pulsed radio frequency fields

著者: Linz KW, von Westphalen C, Streckert J, Hansen V, Meyer R
掲載誌: Bioelectromagnetics 1999; 20 (8): 497-511
RISフォーマットで参考文献をダウンロード

この研究は、単離された心室筋細胞の膜電位、活動電位、L型Ca（2+）電流およびカリウム電流に対する180、900、および1800 MHzの無線周波（RF）電磁界ばく露の影響を調べた。実験にを用いた。ット筋細胞（試料数90）とラット筋細胞（試料数20）を用いた。電磁界ばく露には、方形導波管（1800 MHz （SARは、80, 480, 600, 720, 880 mW/kg）、および900 MHz（同250 mW/kg））、またはTEMセル（180 MHz, 80 mW/kg および900 MHz, 15 mW/kg）を用いた。1800 および900 MHzは、携帯電話のGSM規格に拠ってパルス化した。細胞膜の電気的パラメータは全細胞パッチクランプ法により測定した。その結果、試験した電気生理学的パラメータはいずれも、RF電磁界ばく露によって有意に変化しなかった；別の物理的刺激として、温度を36℃から24℃に下げた場合、電流振幅は約50％低下し、L型Ca（2+）電流の定常状態活性化パラメータおよび不活性化パラメータの電圧依存性は約5 mVシフトした；しかし、この低温において、L型Ca（2+）電流に対するRF（900 MHz、250 mW / kg; 1800 MHz、480 mW / kg）の影響は見られなかった、と報告している。

The detailed summary of this article is not available in your language or incomplete. Would you like to see a complete translation of the summary? Then please contact us →

研究目的（著者による）

To check whether the fields transmitted from GSM-phones (900 and 1800 MHz) and other communication devices like police radio equipment (180 MHz) are able to influence the electrical characteristics of excitable cells (whether the L-type Ca2+-current can be influenced by the presence of these fields).

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 1,800 MHz
Modulation type: pulsed
ばく露時間: continuous for 2 min
  • 電力: 1.8 W peak (0.2, 1.2 and 1.8 W for guinea-pig cells)
  • SAR: 720 mW/kg average over time (unspecified) (80, 480 and 720 mW/kg for guinea-pig cells)
  • 電力: 2.2 W peak (1.5, 1.8 and 2.2 W for rat cells)
  • SAR: 880 mW/kg average over time (unspecified) (600, 720 and 880 mW/kg for rat cells)
ばく露2: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 2 min
  • SAR: 250 mW/kg average over time (unspecified)
ばく露3: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 2 min
  • SAR: 15 mW/kg average over time (unspecified)
ばく露4: 180 MHz
Modulation type: CW
ばく露時間: continuous for 2 min
  • SAR: 80 mW/kg average over time (unspecified)

General information

Isolated ventricular myocytes from guinea-pig were exposed to RF fields of 1800 MHz, 900 MHz, and 180 MHz and rat ventricular myocytes to RF fields of 1800 MHz. An experiment consisted of six phases, each one lasting about two minutes: control, exposure, control, control, sham exposure, control. Exposure and sham exposure were exchanged alternately. Usually all six phases were carried out on the same cell. If this was not possible, two cells from the same animal, each one measured in three phases, were paired.

ばく露1

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 2 min
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional information

GSM-standard
ばく露装置
ばく露の発生源／構造
  • 導波管
  • 50 cm long, 12 cm wide and 3 cm high
チャンバの詳細 The experimental setup consisting of standard patch-clamp electrophysiology-equipment and an RF exposure system was mounted on a shock-absorbing platform in a Faraday cage. The RF exposure system consisted of a signal generator and an exposure device containing the chamber with the cell suspension. Depending on the frequencies applied, two different signal generators and three different exposure devices, i.e. a TEM-cell and two different rectangular waveguides, were used. The waveguides were designed for single-mode operation of the H10-mode. The coaxial line to waveguide transitions were geometry-optimized for suitable matching and low VSWR. The waveguides and the adaptors were made of brass.
ばく露装置の詳細 The specimen was kept in a constantly perfused temperature-controlled experimental chamber. The round experimental chamber, which was filled with 200 µl of cell suspension, was made of acrylic (inner diameter 10 mm, height 6 mm), and its bottom consisted of a glass coverslip to allow visual control of the cells by an inverted microscope. The outer shape of the chamber holder varied to fit the different exposure devices. All three exposure devices had an aperture in the centre of the bottom plate covered by copper meshes, above which the glass bottom of the experimental chamber was placed. Light and the patch-clamp electrode entered the exposure devices via an opening (diameter 10 mm) in the top plate of the device and an additional hole in the septum of the TEM-cell.
Additional information Temperature in the presence and the absence of the RF field was checked in separate experiments during which a temperature sensing device was introduced into the chamber. Experiments were carried out at 36 and 24 °C.
パラメータ
測定量 値 種別 Method Mass 備考
電力 1.8 W peak - - 0.2, 1.2 and 1.8 W for guinea-pig cells
SAR 720 mW/kg average over time 計算値 unspecified 80, 480 and 720 mW/kg for guinea-pig cells
電力 2.2 W peak - - 1.5, 1.8 and 2.2 W for rat cells
SAR 880 mW/kg average over time 計算値 unspecified 600, 720 and 880 mW/kg for rat cells
測定および計算の詳細

Since direct measurement of the field was impossible for electrical and physiological reasons, an indirect evaluation using computer simulations starting from the field in the empty exposure device had to be performed. The test setup in the environment of the experimental chamber with the cell suspension was modelled and calculated by an in-house FDTD simulation tool based on XFDTD. The electrical material parameters (permittivity and conductivity) which could not be taken from the literature were measured with an RF network analyzer at 900 and 1800 MHz. Field homogeneity analysis showed that on the top side of the glass cover slip where the measured cells were located the field appeared very uniform. The computed electrical field strength on the axes of the empty rectangular waveguide (763 V/m) and at the location of the cells (54 V/m) as well as the SAR (3.19 W/kg) for an input power of 1 W CW were determined. From these values the actually applied time-averaged SAR as a function of the peak power of the square-modulated RF signal was calculated.

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 2 min
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional information

GSM-standard. The spectral width of the carrier signal was 3.6 kHz.
ばく露装置
ばく露の発生源／構造
  • 導波管
  • 50 cm long, 21 cm wide and 3 cm high
パラメータ
測定量 値 種別 Method Mass 備考
SAR 250 mW/kg average over time 計算値 unspecified -
測定および計算の詳細

The computed electrical field strength on the axes of the empty rectangular waveguide (627 V/m) and at the location of the cells (42 V/m) as well as the SAR (1.66 W/kg) for an input power of 1 W CW were determined. From these values the actually applied time-averaged SAR as a function of the peak power of the square-modulated RF signal was calculated.

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 2 min
Modulation
Modulation type pulsed
Rise time 2.5 µs
Fall time 2.5 µs
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional information

GSM-standard. The spectral width of the carrier signal was 3.6 kHz.
ばく露装置
ばく露の発生源／構造
チャンバの詳細 Design of the TEM-cell and experimental setup have been described in detail in the reference article.
パラメータ
測定量 値 種別 Method Mass 備考
SAR 15 mW/kg average over time 計算値 unspecified -

ばく露4

主たる特性
周波数 180 MHz
タイプ
  • electromagnetic field
特性
  • guided field
ばく露時間 continuous for 2 min
Modulation
Modulation type CW
Additional information

CW was used to simulate the German police communication standard working with FM.
ばく露装置
ばく露の発生源／構造
パラメータ
測定量 値 種別 Method Mass 備考
SAR 80 mW/kg average over time 計算値 unspecified -

Reference articles

  • Wolke S et al. (1996): [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]

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
  • ばく露後

研究の主なアウトカム（著者による）

The results demonstrate that the investigated radiofrequency fields do not interfere with a number of electrical membrane parameters, like resting membrane potential and action potential.

研究の種別:

研究助成

関連論文