Localization of Sodium in Normal and Inhibited Transporting Epithelia

For a number of years we have used an adaptation of Komnick's KSb(OH)6-OsO4 fixation method for the localization of sodium in tissues in order to study transporting epithelia under a number of different conditions. We have shown that in actively transporting rabbit gallbladder epithelium, large quantities of NaSb(OH)6 precipitate are found in the distended intercellular compartment, while localization of precipitate is confined to the inner side of the lateral plasma membrane in inactive gallbladder epithelium. A similar pattern of distribution of precipitate has been demonstrated in human and rabbit colon in active and inactive states and in the inactive colonic epithelium of hibernating frogs.