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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 242 (1985), S. 633-639 
    ISSN: 1432-0878
    Keywords: Secretin ; Pancreas ; Enzyme secretion ; Protein synthesis ; Fine structure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Infusion of synthetic secretin in conscious unrestricted rats for periods up to 24 h was used to study the structural and functional adaptation of pancreatic acinar cells to this secretagogue. Initial dose-response studies established 16 clinical units (CU) per kg and h (corresponding to 4.64 ug x kg-1 x h-1) as optimal dose for persistent stimulation of enzyme discharge. Infusion of this dose led to a slow but progressive depletion of enzyme stores with minimal content by 12 h stimulation. As a result of persistent stimulation total protein synthesis in the acinar cells increased after a lag period of 3 h and reached maximal values 90% above controls by 6 and 12 h secretin infusion. No structural equivalent for pronounced fluid and bicarbonate secretion was observed for either acinar or duct cells over the entire dose range (1 to 64 CU x kg-1 x h-1) and infusion period (1–24 h), except an increased number of coated vesicles in duct cells. Discharge of enzymes from acinar cells was paralleled by a high frequency of exocytotic images at the luminal plasma membrane and was accompanied by the occurrence of membrane fragments in the luminal space, especially after 3 and 6 h secretin infusion. An increased number of lysosomal bodies at these time points especially in the vicinity of the Golgi complex was interpreted in relation to membrane recycling following massive exocytosis. This pattern of structural and functional adaptation of acinar cells following secretin infusion corresponds to previously described changes following caerulein and carbamylcholine stimulation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Proteinase inhibitor ; Feedback regulation ; Cholecystokinin ; Fine structure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Application of a single dose of a new type of proteinase inhibitor camostate (FOY-305) via orogastric tube was used in rats to study the dose-response relationship of resulting pancreatic stimulation. Doses up to 10 mg/ kg failed to elicit any response, while significant decrease in enzyme content and increase in serum CCK-levels were observed with doses ranging from 25 to 400 mg/kg. A single dose of 100 mg/kg was selected for a time-sequence analysis, which revealed a 60 to 70% depletion of enzyme stores persisting over 6 h and reverting to control levels by 12 h. Peak increases in serum CCK-levels (15-fold above the elevation observed after regular food intake) were found after 30 min and persisted as an 8-to 10-fold elevation for at least 3 h, then declined to control levels by 9 h. This prolonged endogenous hormone release and resulting pancreatic stimulation were also verified in a separate group of animals in which volume, protein, and enzyme output were measured after cannulation of the pancreatic duct. While volume secretion was not altered by feeding a single dose of 100 mg/kg FOY-305, protein and enzyme output increased 2-to 3-fold over a period of 7 h. Fine-structural analysis of the pancreas demonstrated efficient depletion of zymogen granules from acinar cells with all doses between 50 and 400 mg/kg, accompanied by the appearance of membrane material in the acinar lumina at 3 and 6 h. The same transient increase in the number of lysosomal bodies predominantly containing mitochondria with all doses above 50 mg/kg was interpreted as increased organelle turnover due to persisting hormonal stimulation.
    Type of Medium: Electronic Resource
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