A B S T R A C T The effects of highly purified natural porcine cholecystokinin (CCK) and synthetic caerulein on the rate of flow of pancreatic juice, the rate of output of amylase, and the rate of release of immunoreactive insulin (IRI) and immunoreactive glucagon (IRG) were simultaneously investigated in the isolated perfused rat pancreas.The maximal flow rate of pancreatic juice was obtained with concentrations of CCK ranging from 0.5 to 10 mU/ml, whereas amylase output was maximal at CCK concentrations from 1 to 10 mU/ml.
The effects of peroral treatment with synthetic trypsin inhibitor on endocrine secretion in response to four different stimuli were investigated in the isolated perfused rat pancreas. After 10 days' treatment pancreatic wet weights and protein and amylase contents in the pancreas were significantly increased. On the other hand, total contents of IRI and IRG in the T.I.-treated and control pancreas were nearly the same. In spite of the lack of alteration in hormone contents, a lower initial phase of IRI response to 8.3 mM glucose, glucose plus 0.1 ng/ml caerulein or 20 mM arginine was observed in the T.I.-treated pancreas. Furthermore, the IRI response to 10 mM theophylline was both slower and the most reduced in the T.I.-treated pancreas. From these observations, it is suggested that short-term peroral administration of synthetic trypsin inhibitor not only has no trophic effect on pancreatic B-cell and A-cell in the rat but also may affect some pathway of insulin secretion from the B-cell to reduce IRI responses to secretagogues.
Pancreatic juice flow and amylase output, and the concentrations of immunoreactive secretin in portal and peripheral blood were simultaneously determined in anesthetized rats in response to intraduodenal instillation of 1-phenyl-1-hydroxy-n-pentane (PHP), a phenyl carbinol derivative induced from one of the constituents of Curcuma. PHP stimulated both pancreatic juice flow and amylase output and increased portal and jugular plasma secretin levels in a dose-related fashion. During intraduodenal instillation of PHP the pH in the second portion of the duodenum remained consistently above 6.3. Infusion of cyclic somatostatin at a dose of 5 microgram/kg/h significantly suppressed the PHP-induced secretin release, though pancreatic flow rate and amylase output were only slightly and insignificantly suppressed. These observations suggest that PHP release secretin by an acid independent mechanism but also stimulates the exocrine pancreas by a mechanism independent of secretin.
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