Bubbles, gating, and anesthetics in ion channels

PHYS 155

Bob Eisenberg, beisenbe@rush.edu, Molecular Bipohysics & Physiology, Rush Medical Center, 1750 W Harrison, Chicago, IL 60612
We suggest that bubbles are the bistable hydrophobic gates responsible for on-off single channel currents. In this view, many types of channels gate by the same physical mechanism dewetting by capillary evaporation but different types of channels use different sensors trigger and control bubbles and gating. Spontaneous emptying of channels has been seen in many simulations. Xenon bubbles have been observed in channels by Dutzler. Bubble formation is an unstable threshold phenomena difficult to simulate reproducibly and thus convincingly. A thermodynamic analysis of a bubble gate using morphometric density functional theory of classical (not quantum) mechanics is more reproducible and less sensitive to details than simulations. Anesthetic actions of inert gases can be easily understood by actions on bubbles. Only experiments can show whether, or when, or which channels actually use bubbles as hydrophobic gates: direct observation of bubbles in channels are needed.