Electrical polarization of phosphatidylserine bilayer membranes by calcium ions

Bilayer membranes formed from a decane solution of phosphatidylserine were polarized by an applied potential. An open circuit voltage pulse following the brief short circuit of the polarized membrane was observed if Ca²⁺ was present in the aqueous phase on both sides of the membrane. This polarization response is proportional to the initial applied voltage and increases with Ca²⁺ concentration until a maximum response of 11% is obtained at 0.5 mM. Two possible mechanisms, voltage-dependent Ca²⁺ binding and border conduction are discussed.