Permeability changes induced by 130 GHz pulsed radiation on cationic liposomes loaded with carbonic anhydrase
✍ Scribed by Alfonsina Ramundo-Orlando; Gian Piero Gallerano; Pasquale Stano; Andrea Doria; Emilio Giovenale; Giovanni Messina; Mauro Cappelli; Marco D'Arienzo; Ivan Spassovsky
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 214 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0197-8462
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✦ Synopsis
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 Δ__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 °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 Δ__A/min = 0.0026 ± 0.0010 (n = 11) to Δ__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 °C), above the phase transition temperature of POPC liposomes. Bioelectromagnetics 28:587–598, 2007. © 2007 Wiley‐Liss, Inc.