Investigation on the influence of a generic UMTS (Universal Mobile Telecommunications System) signal on barrier tightness, transport processes and the morphology of porcine brain microvascular endothelial cell cultures serving as an in vitro model of the blood-brain barrier.
Response of the cells to thermal stress was also investigated (with elevated temperatures of 37.3 - 39°C).
| Exposure | Parameters |
|---|---|
|
Exposure 1:
1.966 GHz
Exposure duration:
continuous for 1 up to 3.5 days
|
|
| Frequency | 1.966 GHz |
|---|---|
| Type | |
| Charakteristic |
|
| Exposure duration | continuous for 1 up to 3.5 days |
| Exposure source |
|
|---|---|
| Chamber | Two radial waveguides each containing up to 28 samples were placed into an incubator and were used in turns as the exposure device or sham-exposure device. The samples in each waveguide were arranged symmetrically near the rim. The reflections were reduced by a 5-mm flat absorber along the waveguide perimeter. |
| Setup | The filters carrying the cell cultures were installed in cylindrical tubes between two discoid gold electrodes. Each sample holder was equipped with a two-electrode system for impedance monitoring. The leads of the electrodes were conducted upward through the metal caps that sealed the cartridges. Thus simultaneous RF-field exposure and LF impedance measurement was possible. |
| Additional info | The barrier tightness was monitored continuously by TEER measurement using impedance spectroscopy described in detail by Wegener et al. in Brain Res. 853, 115-124 (2000). Impedance analysis was carried out in the frequency range from 1 Hz to 500 kHz applying a sinusoidal voltage of ~30 mV amplitude. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| electric field strength | 34 V/m | mean | measured and calculated | - | ± 40% SD |
| SAR | 1.64 W/kg | average over mass | calculated | cf. remarks | vessel with 3.5 ml solution |
| electric field strength | 10.8 V/m | mean | measured and calculated | - | - |
| electric field strength | 3.4 V/m | mean | measured and calculated | - | - |
No evidence of radiofrequency-field-induced disturbance of the function of the blood-brain barrier was found. After and during exposure, the tightness of the blood-brain barrier quantified by 14C-sucrose permeation as well as by trans-endothelial electrical resistance remained unchanged compared to sham-exposed cultures. Permeation of transporter substrates at the blood-brain barrier as well as the localization and integrity of the tight junction proteins occludin and ZO1 were not affected either.
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