Cardiac Gap Junctions and Gap Junction-Associated Vesicles: Ultrastructural Comparison of In Situ Negative Staining With Conventional Positive Staining

• Published in: Circulation research Vol. 64; no. 3; pp. 501 - 514
• Main Authors: Chen, Li, Goings, Gwendolyn E, Upshaw-Earley, Judy, Page, Ernest
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Heart Association, Inc 01.03.1989; Lippincott
• Subjects: Animals; Biological and medical sciences; Cell Membrane - ultrastructure; Female; Fundamental and applied biological sciences. Psychology; gap junctions; Heart; Heart Atria - ultrastructure; Heart Ventricles - ultrastructure; Intercellular Junctions - ultrastructure; Lanthanum; Microscopy, Electron - methods; Myocardium - ultrastructure; Organelles - ultrastructure; Rats; Rats, Inbred Strains; Sheep; Staining and Labeling - methods; Vertebrates: cardiovascular system; Heart; Plasmalemma; Vertebrata; Mammalia; Ultrastructure; Histological labelling; Cell junction; Circulatory system; Gap junction; Heart cell
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/01.RES.64.3.501

By comparing in situ negative staining of mammalian heart muscle using La(NO3)3 with conventional positive staining by uranium and lead salts, we showed that 1) the membrane area of rat cardiac gap junctions (GJs) at the intercalated disks is threefold to fourfold greater than previously thought; 2) connexon arrays of cardiac GJ are subdivided into microdomains by connexon-free aisles; 3) profiles of GJ-associated vesicles (GJAVs) of plasmalemmal origin (which are present extracellularly and sharply localized at three extracellular sites) are paired to form GJs with each other and with myocyte plasmalemma; 4) some GJAVs contain arrays of assembled connexons; and 5) myocytes contain intracytoplasmic complexes lying within cylindrical or cigar-shaped membranes and consisting of GJs and multiple vesicles apparently dissociating from these GJs.