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.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
Exposure duration:
40 min
|
|
The rabbits (n=46) were divided in two groups: Group 1: exposed (n=26) and Group 2: sham exposed (n=20)
| Frequency | |
|---|---|
| Type | |
| Exposure duration | 40 min |
| Additional info | 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. |
| Exposure source |
|
|---|---|
| Chamber | copper drum; room temperature maintained at 22.5°C |
| Setup | 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 info | 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. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 350 mT | - | measured | - | - |
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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