Gap Junctions. Structural Changes after Uncoupling Procedures

• Published in: The Journal of cell biology 1977-03, Vol.72 (3), p.628-641
• Main Author: Peracchia, Camillo
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Animals; Calcium; Cells; Dinitrophenols - pharmacology; Gap junctions; Hepatocytes; Hypoxia; Intercellular Junctions - drug effects; Intercellular Junctions - metabolism; Intercellular Junctions - ultrastructure; Liver; Liver - ultrastructure; P branes; Perfusion; Platinum; Rats; Stomach; Stomach - ultrastructure; Sucrose - pharmacology
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.72.3.628

The freeze-fracture appearance of rat stomach and liver gap junctions changes after uncoupling procedures such as inhibition of the metabolism of perfusion with hypertonic sucrose. In control stomach, either fixed immediately or kept for 1 h in a well-oxygenated Tyrode's solution at 37°C, most gap junctions between mucous cells contain particles irregularly packed at an average center-to-center spacing of 10.3-10.5 nm. After 1-h treatment with 2,4-dinitrophenol (DNP), at the same temperature and oxygenation, most particles aggregate hexagonally at an average spacing of ∼8.5 nm. Similar changes are seen in hypoxic specimens. In control liver, fixed by perfusion, most junctional particles are irregularly packed at an average center-to-center spacing of ∼10 nm. Small areas of fairly regular hexagonal packing are occasionally seen, where the average particle spacing is 9.2-9.5 nm. In hypoxic liver, the junctional particles form regular hexagonal packings in which the average center-to-center particle spacing is ∼8.5 nm. In liver perfused with hypertonic sucrose-calcium solutions, following EDTA solutions, most junctions are pulled apart. The separated junctional membranes, expected to be highly impermeable, contain particles regularly and tightly packed as in hypoxic or DNP-treated junctions. Preliminary measurements indicate also a possible change in particle diameter, from ∼8.6 nm (control) to ∼7.7 nm (treated). The structural changes are similar to those previously reported in crayfish and may reflect conformational changes in particle subunits resulting in functional uncoupling.