Effect of local anesthetic lidocaine on electrostatic properties of a lipid bilayer

The influence of the local anesthetic lidocaine on electrostatic properties of a lipid membrane bilayer was studied by molecular dynamics simulations. The electrostatic dipole potential, charge densities, and orientations of the headgroup angle have been examined in the presence of different amounts of charged or uncharged forms of lidocaine. Important changes in the membrane properties caused by the presence of both forms of lidocaine are presented and discussed. Our simulations have shown that both charged and uncharged lidocaine cause almost the same increase in the electrostatic potential in the middle of the membrane, although for different reasons. The increase, similar to 90 mV for 9 mol % of lidocaine and 220 mV for 28 mol % of lidocaine, is of a size that may affect the functioning of voltage-gated ion channels.