Polymer inaccessible volume changes during opening and closing of a voltage-dependent ionic channel

Abstract
Osmotic stress can be used to estimate the internal volume change during the opening and closing of a voltage gated ionic channel. Mitochondrial voltage-dependent anion channels, from rat liver and from Neurospora, reconstituted into planar lipid bilayers show a change of 2 to 4 .times. 104 .ANG.3 in internal volume, a large change inconsistent with a blocking or local gating model but supporting models with major closure of the channel space.