After a twelve-day culture period, cells were sham exposed or magnetic field exposed (1 mT or 3 mT). To test the specific currents of calcium channels with patch-clamp technique, the voltage-gated sodium and potassium ion channels were blocked by tetrodotoxin (blocks sodium ion channels), tetraethylammonium (blocks potassium ion channels) and 4-aminopyridine (blocks potassium ion channels).
|Setup||the exposure system consisted of two four-coil setups (2 coils with 56 windings, 2 coils with 50 windings), each of which was placed inside a Mu-metal box; two fans were mounted per box to guarantee enough atmospheric exchange within the exposure chambers; both setups (see additional information) were placed inside a commercial incubator to ensure constant environmental conditions (37°C, 5% CO2, 95% humidity); temperature was continuously monitored and maintained at 37-37.5°C during exposure; temperature difference between the chambers did not exceed 0.1°C|
|Sham exposure||A sham exposure was conducted.|
|Additional info||currents in the bifilar coils could be switched between parallel for field exposure and non-parallel for sham control, thus the field exposure and sham exposure can be achieved at the same time|
|magnetic flux density||1 mT||-||measured||-||-|
No influence of the magnetic field exposure on the whole cell currents and on high and low-voltage activated calcium channels was observed when compared to sham exposure. Additionally, no difference was found in the basal levels of the calcium concentration between the exposed and the sham exposed neurons. However, the analysis of the dynamic response using a potassium stimulus yielded in a dose-dependent significant derease in the calcium concentration of exposed cells compared to sham exposed cells. An addition of thapsigargin prevented this effect.
The authors conclude that extremely low frequency magnetic fields influence the calcium dynamics in neurons from the entorhinal cortex via a calcium channel independent mechanism.