Exocytosis and movement of zymogen granules observed by VEC-DIC microscopy in the pancreatic tissue en bloc

• Published in: American Journal of Physiology: Cell Physiology 2000-10, Vol.279 (4), p.C1177-C1188
• Main Authors: Ishihara, Yukio, Sakurai, Takashi, Kimura, Taizou, Terakawa, Susumu
• Format: Article
• Language: English
• Subjects: Animals; Bethanechol - pharmacology; Biological Transport - drug effects; Biological Transport - physiology; Cells, Cultured; Chelating Agents - pharmacology; Cytoplasmic Granules - metabolism; Cytoplasmic Granules - ultrastructure; Dose-Response Relationship, Drug; Egtazic Acid - pharmacology; Enzyme Precursors - metabolism; Enzyme Precursors - ultrastructure; Exocytosis - drug effects; Exocytosis - physiology; Guinea Pigs; Light; Male; Microscopy, Interference - methods; Microscopy, Video; Muscarinic Agonists - pharmacology; Pancreas - drug effects; Pancreas - enzymology; Pancreas - ultrastructure; Potassium - metabolism; Rabbits; Sincalide - pharmacology
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.2000.279.4.c1177

1  First Department of Surgery and 2  Photon Medical Research Center, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan The dynamic aspects of exocytosis, especially in the normal acinar tissue en bloc, have remained unclear. We visualized exocytosis directly in the tissue of the exocrine pancreas of rodents by video-enhanced contrast-differential interference contrast (VEC-DIC) microscopy to investigate various exocytosis-related rates and the relationship between the movement of granules and exocytotic responses. Stimulation of the tissue with bethanechol or cholecystokinin caused many of the zymogen granules in the apical pole to disappear abruptly. The exocytotic transients of individual granules were completed in 0.48-0.65 s. Granules destined to participate in the exocytotic response moved randomly at velocities of ~0.06 µm/s or less during stimulation. In the tissue preparation, granules located far from the apical pole frequently moved back and forth for 1-7 µm without showing exocytosis. Colchicine suppressed this movement and the late phase of the secretory response. Real-time (VEC-DIC) observation of granule dynamics revealed that the initial step of exocytosis was not coupled directly with the microtubule-dependent translocation but with a continuous, slow Brownian fluctuation of granules. granule movement; pancreas; video microscopy; video-enhanced contrast-differential interference contrast microscopy