EFFECT OF MICROWAVE-RADIATION ON PERMEABILITY OF LIPOSOMES - EVIDENCEAGAINST NONTHERMAL LEAKAGE

The effect of 2.45 GHz microwave radiation on the permeability of unil amellar phosphatidylcholine liposomes has been studied. Leakage of 5(6 )-calboxyfluorescein from the liposomes was measured using spectrofluo rimetry after exposure to either microwaves or thermal heating for 5-2 0 min intervals. The exposure temperature, 37.6 +/- 0.5 degrees C, was well above the phase transition temperature of the lipid membrane. Th e microwave exposure did not result in any non-thermal increase in per meability above that produced by thermal heating. This study refutes t he results reported by Saalman et al. [1] in which an increased liposo me permeability due to microwave exposure was reported. The refined an alysis in the present study shows that this increased liposome permeab ility was not a non-thermal microwave effect.