title: Chemical nature of atrial specific granules.
abstract: The specific granules are argentafugic when ultrathin sections of Araldite-embedded atria are stained according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiery. The entire core of the atrial specific granules is moderately positive after ultrathin sections of glutaraldehyde-fixed, glycol methacrylate- (GMA-) embedded atria are stained with phosphotungstic acid at a low pH. A similar reaction is shown by the cell coat, intercalated discs, residual bodies (C-granules), and Z-discs, as well as by a very small portion of the Golgi complex. Analogous results are obtained with semithin sections of GMA- embedded atria stained according to the periodic acid-Schiff (PAS) technique. In ultrathin sections of GMA-embedded atria stained with dialyzed colloidal iron (DI), the cell coat of the cardiocytes is positive, unlike all the other cytoplasmic organelles. When ultrathin sections of GMA-embedded atria are incubated with proteolytic enzymes (pronase, pepsin, or trypsin), atrial specific granules and Z-bands and, to a much lesser degree, cell coat and sarcolemma are selectively digested. Proteins are also distinctly demonstrated in the paranuclear specific granules by a variety of histochemical techniques. These results indicate that atrial specific granules are rich in proteins and possess a weak complement of complex carbohydrates.
mesh_terms: D000818:Animals; D050260:Carbohydrate Metabolism; D005260:Female; D006003:Glycogen / Q000378:metabolism; D006056:Golgi Apparatus / Q000648:ultrastructure; D006325:Heart Atria / Q000648:ultrastructure*; D009124:Muscle Proteins / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D012834:Silver; D013194:Staining and Labeling
chemical_list: D009124:Muscle Proteins; D012834:Silver; D006003:Glycogen