ABSTRACT
This chapter focuses on the transport of lipophilic ions in lipid bilayer membranes and presents the lipid bilayer as a continuous medium without pores. It also focuses on the properties of lipid bilayers in the presence of similar, but oppositely charged ions, such as tetraphenylphosphonium, tetraphenylarsonium and tetraphenylborate. The thermodynamic parameters relevant for the total ion potential energy profile of ions are difficult to obtain and are, generally, “laboratory and method dependent.” Ion structure determines the depth of the “chemical” ion energy well and ion size the Born-image work of transfer from the aqueous solution into the bilayer. The internal membrane transport is effectively isolated from the aqueous solution for a considerable period of time, since it takes some time before the transmembrane translocation current becomes comparable to one supported by ion diffusion in water. The kinetics of the transfer of ions between the aqueous solution and the membrane are inadequately understood.
