Effect of low frequency, low amplitude magnetic fields on the permeability of cationic liposomes entrapping carbonic anhydrase: I. Evidence for charged lipid involvement.
The influence of low frequency (4-16 Hz), low amplitude (25-75 mu T) magnetic fields on the diffusion processes in enzyme-loaded unilamellar liposomes as bioreactors was studied. Cationic liposomes containing dipalmitoylphosphatidylcholine, cholesterol, and charged lipid stearylamine (SA) at different molar ratios (6:3:1 or 5:3:2) were used. Previous kinetic experiments showed 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 sinusoidal (50 mu T peak) and parallel static (50 mu T) magnetic fields the enzyme activity, as a function of increased diffusion rate of p-NPA, rose from 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 presence of combined sinusoidal (AC) and static (DC) magnetic fields affected the p-NPA diffusion rates. No enzyme leakage was observed. Such studies suggest a plausible link between the action of extremely low frequency magnetic field on charged lipids and a change of membrane permeability.
Ramundo-Orlando
A
A
Institute of Experimental Medicine, CNR, Rome, Italy.
Morbiducci
U
U
Mossa
G
G
D'Inzeo
G
G
D000818:Animals; D001698:Biomedical Engineering; D019149:Bioreactors; D002256:Carbonic Anhydrases; D002412:Cations; D002417:Cattle; D004574:Electromagnetic Fields / Q000009:adverse effects*; D066298:In Vitro Techniques; D008081:Liposomes; D010539:Permeability
D002412:Cations; D008081:Liposomes; D002256:Carbonic Anhydrases