Effect of low frequency, low amplitude magnetic fields on the permeabilityof cationic liposomes entrapping carbonic anhydrase I. Evidence for charged lipid involvement
A. Ramundo-orlando et al., Effect of low frequency, low amplitude magnetic fields on the permeabilityof cationic liposomes entrapping carbonic anhydrase I. Evidence for charged lipid involvement, BIOELECTROM, 21(7), 2000, pp. 491-498
The influence of low frequency (4-16 Hz), low amplitude (25-75 mu T) magnet
ic fields on the diffusion processes in enzyme-loaded unilamellar liposomes
as bioreactors was studied. Cationic liposomes containing dipalmitoylphosp
hatidylcholine, cholesterol, and charged lipid stearylamine (SA) at differe
nt molar ratios (6:3:1 or 5:3:2) were used. Previous kinetic experiments sh
owed a very low self-diffusion rate of the substrate p-nitrophenyl acetate
(p-NPA) across intact Liposome bilayer. After 60 min of exposure to 7 Hz si
nusoidal (50 mu T peak) and parallel static (50 mu T) magnetic fields the e
nzyme activity, as a function of increased diffusion rate of p-NPA, rose fr
om 17 +/- 3% to 80 +/- 9% (P < .0005, n = 15) in the 5:3:2 liposomes. This
effect was dependent on the SA concentration in the liposomes. Only the pre
sence of combined sinusoidal (AC) and static (DC) magnetic fields affected
the p-NPA diffusion rates. No enzyme leakage was observed. Such studies sug
gest a plausible link between the action of extremely low frequency magneti
c field on charged lipids and a change of membrane permeability. (C) 2000 W
iley-Liss, Inc.