この研究は、動脈圧受容器に対する人工静磁界（SMF）と地球磁場（GMF）の相互に関連しあう影響について調べた。意識のあるウサギは擬似ばく露群（n = 20）、ばく露群（n = 26）に分けられ、それぞれ、副鼻腔圧受容器領域に、40分間、SMFとGMF擾乱の組み合わせばく露（または擬似ばく露）を行った。その前と後に、圧反射感受性（BRS）を測定した。SMFはNd2‐Fe14‐B合金磁石で発生させた。GMF擾乱は、２種類を用いた。その地方の地磁気観測所から提供されたK指標およびAk指標で決定されたものである。圧受容器の位置でのSMFは0.35 Tであった。BRSは、昇圧薬（フェニレフリン）および降圧薬（ニトロプルシド）の注射による昇圧および降圧試験時の平均動脈圧（MAP）および心拍数（事前の安静値に対するパーセンテージで表示）のピーク応答から推定された。その結果、ニトロプルシド降圧試験でBRSの有意な上昇が見られた（実験開始前0.78±0.1、SMFばく露後1.15±0.14 bpm / mmHg％；P < . 0002）；フェニレフリン昇圧試験ではBRSの上昇傾向が観察された；SMFばく露前に、現実のK指数とMAPの間に有意な正の相関が見られ、K指数とBRSには負の相関が見られた； SMFばく露後に、GMF擾乱の低下がBRS低下を引き起こすことが観察された、と報告している。
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To investigate interrelated effects of artificial static magnetic field and natural geomagnetic field on arterial baroreceptors in rabbits.
For this purpose baroreflex sensitivity was investigated before and after local 0.35 Tstatic magnetic field exposure of the carotid sinus baroreceptor region in conjunction with geomagnetic field activity during the experiment, determined by K- and Ak-index.
The geomagnetic field has internal and external components: The internal geomagnetic field originates in the earth and is known to geophysicists as the main field of the earth. The second part is its time varying component.
K-index: the diurnal variation of the naturally occuring time varying geomagnetic field disturbance level. K-indices are quasilogarithmic means of geomagnetic disturbance over 3 h intervals, reflecting the maximum variation during that period.
Ak: characterizes the magnitude of geomagnetic disturbance over 24 h intervals and is calculated as the sum of K values occuring during 24 h.
| ばく露 | パラメータ |
|---|---|
ばく露1:
ばく露時間:
40 min
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The rabbits (n=46) were divided in two groups: Group 1: exposed (n=26) and Group 2: sham exposed (n=20)
| 周波数 |
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|---|---|
| タイプ |
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| ばく露時間 | 40 min |
| Additional information | Static magnetic field was used for exposure purpose. Reference article: Gmitrov J, Ohkubo C. 1998. Static magnetic field effect on baroreflex sensitivity in rabbits. Electro-Magnetobiol 17:217-228. |
| ばく露の発生源／構造 |
|
|---|---|
| チャンバの詳細 | copper drum; room temperature maintained at 22.5°C |
| ばく露装置の詳細 | The rabbits lay prone in the copper drum with their head and neck out of the drum and their heads fixed between the metal ring and the drum and manipulators with magnets positioned under sinocarotid baroreceptors of the neck. |
| Additional information | At 50th min after the beginning of the experiment (not exposure), 490 mm² cylindrical sham or neodium-iron-boron alloy magnets were positioned for 65 min (from 50 to 115 min) with opposite poles under the right and left carotid sinus area. |
| 測定量 | 値 | 種別 | Method | Mass | 備考 |
|---|---|---|---|---|---|
| 磁束密度 | 350 mT | - | 測定値 | - | - |
Prior to static magnetic field exposure, a significant positive correlation was revealed between actual K index values and mean arterial blood pressure and a negative correlation of the K index with baroreflex sensitivity.
After static magnetic field exposure the authors observed an attenuation of the geomagnetic disturbance negative effect on arterial baroreceptors. Baroreflex sensitivity significantly increased both in days with low and high geomagnetic disturbance, however the increment of baroreflex sensitivity was larger during the experiments with high geomagnetic field disturbance.
The data may partially explain the mechanisms of the adverse effect of geomagnetic field disturbance on the cardiovascular system. Clinical trials should be performed to support these data. There is a strong expectation that 0.35 T static magnetic field local exposure to baroreceptors will be effective in decreased baroreflex sensitivity, due to the favorable static magnetic field effect on the arterial baroreflex.
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