The aim of the study was to verify the existence of specific effects of millimeter waves on excitable tissues. The effects of a short-term exposure to millimeter waves on the compound action potential conduction in an isolated frog sciatic nerve preparation were investigated. Compound action potentials were evoked by either a low-rate or a high-rate electrical stimulation of the nerve (4 and 20 paired pulses/s, respectively).
| Exposure | Parameters |
|---|---|
|
Exposure 1:
41.15–51.7 GHz
Modulation type:
CW
Exposure duration:
30 min
|
|
|
Exposure 2:
40.5–51.8 GHz
Modulation type:
CW
Exposure duration:
10 - 60 min
|
|
| Frequency | 41.15–51.7 GHz |
|---|---|
| Type | |
| Exposure duration | 30 min |
| Modulation type | CW |
|---|
| Exposure source | |
|---|---|
| Distance between exposed object and exposure source | 0.052 m |
| Setup | sciatic nerves were laid in the slot of the exposure chamber and exposed under thin layer of mineral oil; the nerve was aligned with the E-field. |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| power density | 0.26 mW/cm² | minimum | measured | - | - |
| power density | 2.6 mW/cm² | maximum | measured | - | - |
| Modulation type | CW |
|---|
| Exposure source |
|
|---|---|
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| power density | 0.23 mW/cm² | minimum | measured | - | - |
| power density | 3 mW/cm² | maximum | measured | - | - |
The low-rate stimulation (field 1-9) did not change the functional state of the nerve, and the amplitude, latency, and peak latency of compound action potentials could stay virtually stable for hours. Microwave exposure for 10-60 min at 0.24-1.5 mW/cm², either at various constant frequencies or with a stepwise frequency change, did not cause any detectable alterations in compound action potential conduction.
The high-rate electrical stimulation produced gradual and reversible decrease of the amplitude of test compound action potentials and increased their latencies and peak latencies. These changes were essentially the same with and without irradiation, except for attenuation of the decrease of the test compound action potential amplitude. This effect was revealed at both field intensities, but was statistically significant only for certain frequencies of the irradiation. Within the studied limits, this effect appeared to be dependent on the frequency rather than on the intensity of the irradiation, but this observation requires additional experimental confirmation.
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