For more than seven decades, the electric field of biological membranes has been regarded as a one-dimensional quantity, defined solely by the component normal to the bilayer (E_VERT). Here, we challenge this conventional view by developing a device that generates a horizontal electric field within the hydrophobic core of a lipid bilayer (E_HORZ). The device incorporates micrometre-scale electrodes embedded within the bilayer's torus, enabling the steady generation of E_HORZ. Applied E_HORZ selectively and reversibly accelerates the slow inactivation of a voltage-gated potassium channel, while leaving activation essentially unchanged. Physical considerations reveal that E_HORZ naturally arises wherever membrane potential varies spatially, such as at the wavefront of an action potential, implying that it is inherent to many physiological processes. This E_HORZ system provides experimental access to fully three-dimensional membrane electric fields, revealing a previously overlooked dimension of membrane bioelectricity.
Categories: physics.bio-ph