LPS (lipopolysaccharides; to study the influence of the magnetic field on differentiated macrophages and their nitric oxide production; LPS activates the nitric oxide synthase) and TPA (tetradecanoylphorbol acetate; TPA is known to induce a direct activation of NADPH-oxidase) were used as positive controls.
Enzymes such as NAD(P)H-oxidases mediate the main production of free radicals (ROS) in macrophages. The authors assume that the activation of NADH-oxidase plays a major role in phagocytic cells and is responsible for the magnetic field-induced free radical production. To study this, the specific NADPH-oxidase inhibitor DPI (diphenyleneiodonium chloride) was used, which does not affect NADH-oxidase activity. It makes it possible to distinguish between the two pathways (NADH-oxidase/NADPH-oxidase).
Exposure duration: experiment 1: 45 min; experiment 2: 45 min up to 24 h
|Exposure duration||experiment 1: 45 min; experiment 2: 45 min up to 24 h|
|magnetic flux density||1 mT||unspecified||measured||-||-|
The results show a significant increase of free radical production after exposure to 50 Hz electromagnetic fields to promonocytes and macrophages, indicating the cell-activating capacity of extremely low frequency magnetic fields.
After exposure mainly superoxide anion radicals were produced, both in macrophages and also in their precursor cells (monocytes). Magnetic field-induced free radical production was not inhibited by DPI, whereas TPA-induced free radical production was diminished by about 70%. Since DPI lacks an inhibitory effect in magnetic field-exposed cells, the authors suggest that 50 Hz magnetic field stimulates the NADH-oxidase pathway to produce superoxide anion radicals, but not the NADPH pathway. Magnetic field-exposed cells show no detectable production of NO2-.