(464i) Ion Transport Near Biological Membranes II: In-Plane Signal Propagation

This second talk describes the spatiotemporal nature of electrochemical signal propagation near lipid membranes, highlighting the role of long-range electrostatic forces in ionic reorganization. Using large-scale numerical simulations and analytical solutions, we show that spatially localized pumping results in three distinct regimes along the membrane. These regimes exhibit distinct scaling of the transmembrane electrical potential: (i) a constant potential near-field region, (ii) a monopole-like intermediate region, and (iii) a dipole-like far-field region. We find that upon constant pumping, the monopolar front expands radially along the membrane with a steady velocity that is enhanced by the dielectric mismatch and the finite thickness of the lipid membrane. For unmyelinated lipid membranes in physiological settings, we estimate the propagation speed to be ~50 m/s, which is faster than diffusive reorganization. Taken together, our work shows that ionic transport across a lipid membrane induces transient long-ranged electric fields in electrolyte solutions, which may play hitherto unappreciated roles in biological signaling.