title: Permeability changes induced by 130 GHz pulsed radiation on cationic liposomes loaded with carbonic anhydrase.
abstract: The effects of pulsed 130 GHz radiations on lipid membrane permeability were investigated by using cationic liposomes containing dipalmitoyl phosphatidylcholine (DPPC), cholesterol, and stearylamine. Carbonic anhydrase (CA) was loaded inside the liposomes and the substrate p-nitrophenyl acetate (p-NPA) added in the bulk aqueous phase. Upon permeation across the lipid bilayer, the trapped CA catalyzes the conversion of the p-NPA molecules into products. Because the self-diffusion rate of p-NPA across intact liposomes is very low the CA reaction rate, expressed as Delta A/min, is used to track membrane permeability changes. The effect of 130 GHz radiation pulse-modulated at low frequencies of 5, 7, or 10 Hz, and at time-averaged incident intensity (I(AV)) up to 17 mW/cm(2) was studied at room temperature (22 degrees C), below the phase transition temperature of DPPC liposomes. At all the tested values of I(AV) a significant enhancement of the enzyme reaction rate in CA-loaded liposomes occurred when the pulse repetition rate was 7 Hz. Typically, an increase from Delta A/min = 0.0026 +/- 0.0010 (n = 11) to Delta A/min = 0.0045 +/- 0.0013 (n = 12) (P < 0.0005) resulted at I(AV) = 7.7 mW/cm(2). The effect of 130 GHz pulse-modulated at 7 Hz was also observed on cationic liposomes formed with palmitoyloleoyl phosphatidylcholine (POPC), at room temperature (22 degrees C), above the phase transition temperature of POPC liposomes.
authors.affiliation: Istituto di Neurobiologia e Medicina Molecolare, National Research Council (CNR), Via del Fosso del Cavaliere, Rome, Italy. alfonsina.ramundoorlando@artov.inmm.cnr.it
authors.forename: Alfonsina
authors.initials: A
authors.lastname: Ramundo-Orlando
authors.forename: Gian Piero
authors.initials: GP
authors.lastname: Gallerano
authors.forename: Pasquale
authors.initials: P
authors.lastname: Stano
authors.forename: Andrea
authors.initials: A
authors.lastname: Doria
authors.forename: Emilio
authors.initials: E
authors.lastname: Giovenale
authors.forename: Giovanni
authors.initials: G
authors.lastname: Messina
authors.forename: Mauro
authors.initials: M
authors.lastname: Cappelli
authors.forename: Marco
authors.initials: M
authors.lastname: D'Arienzo
authors.forename: Ivan
authors.initials: I
authors.lastname: Spassovsky
mesh_terms: D002256:Carbonic Anhydrases / Q000737:chemistry* / Q000528:radiation effects*; D002412:Cations; D004305:Dose-Response Relationship, Drug; D008051:Lipid Bilayers / Q000737:chemistry* / Q000528:radiation effects*; D008081:Liposomes / Q000737:chemistry* / Q000528:radiation effects*; D008872:Microwaves; D010539:Permeability / Q000528:radiation effects; D011829:Radiation Dosage
chemical_list: D002412:Cations; D008051:Lipid Bilayers; D008081:Liposomes; D002256:Carbonic Anhydrases