Are cell membranes electrorheological fluids?

Living cells maintain transmembrane electric potential difference across the plasma membrane as well as the membranes of various organelles. Using giant vesicles as an in-vitro membrane model system, we explore the effects of electric field on membrane mechanical properties. We discover that bilayers may not behave as simple two-dimensional fluids as commonly assumed but their viscosity may be modulated by electric fields.  We find that membrane viscosity decreases with increasing electric field magnitude, while membrane electric polarization has the opposite effect. The potential impact of coupled endogenous electric fields and membrane fluidity on biological function opens an exciting new direction to explore.