Modification of membrane fluidity in melanin-containing cells by low-level microwave radiation.

Phelan AM, Lange DG, Kues HA, Lutty GA,

Bioelectromagnetics 13(2):131-146, 1992

The treatment of a B16 melanoma cell line with 2.45-GHz pulsed microwaves (10 mW/cm², 10-microseconds pulses at 100 pps, 1-h exposure; SAR, 0.2 W/kg) resulted in changes of membrane ordering as measured by EPR (electron paramagnetic resonance) reporter techniques.

The changes reflected a shift from a more fluid-like phase to a more solid (ordered) state of the cell membrane.

Exposure of artificially prepared liposomes that were reconstituted with melanin produced similar results. In contrast, neither B16 melanoma cells treated with 5-Bromo-2-Deoxyuridine (3 micrograms/day x 7 days) to render them amelanotic, nor liposomes prepared without melanin, exhibited the microwave-facilitated increase of ordering.

Inhibition of the ordering was achieved by the use of superoxide dismutase (SOD), which strongly implicates oxygen radicals as a cause of the membrane changes. The data indicate that a significant, specific alteration of cell-membrane ordering followed microwave exposure. This alteration was unique to melanotic membranes and was due, at least in part, to the generation of oxygen radicals.