Modification of membrane fluidity in melanin-containing cells by low-level microwave radiation.
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.
Phelan
A M
AM
Department of Anesthesiology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205.
Lange
D G
DG
Kues
H A
HA
Lutty
G A
GA
D000818:Animals; D002460:Cell Line; D004578:Electron Spin Resonance Spectroscopy; D008543:Melanins / Q000502:physiology*; D008546:Melanoma, Experimental / Q000503:physiopathology*; D008560:Membrane Fluidity / Q000528:radiation effects*; D051379:Mice; D008872:Microwaves
D008543:Melanins