Identification of channel membrane processes in bilayer lipid membranes by electrochemical techniques

LM GASSA, AE VALLEJO, S ALONSO-ROMANOWSKI AND JR VILCHE

Bioelectrochemistry and Bioenergetics

Elsevier BV

Lugar: Amsterdam The Netherlands; Año: 1997 vol. 42 p. 187 - 192

Electrochemical impedance spectroscopy (EIS) was used to investigate the ionic transport phenomena in multilamellar liposomes (MLV) made of egg yolk phosphatidylcholine (Egg PC), undoped and doped with a low concentration of the antibiotic Gramicidin A (GA) in the presence of Na+, K+ and Cs+ ions. The membrane/GA interaction can be characterized by the changes observed in the low frequency range of the impedance spectra. The present EIS data are compared with previous results obtained with black lipid membranes (BLM) and they are discussed taking into account the differences and similarities of both model systems, such as time constants and resistance under isotonic, hypertonic and hypotonic conditions, as well as the different methods of antibiotic incorporation. Author Keywords: Liposomes; Black lipid membranes; Electrochemical impedance spectroscopy; Cation transport; Channel/membrane contributions