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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 18 (1991), S. 0 
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. The effects of neurotensin on pancreatic exocrine secretion were investigated both in the intact whole pancreas and in the isolated, blood-perfused pancreas ex vivo in anaesthetized dogs.2. Intravenous (i.v.) injections of neurotensin (0.01-1 nmol/kg) elicited dose-dependent increases in the secretory rate of pancreatic juice without changes in plasma levels of cholecystokinin (CCK). The concentration of bicarbonate in the pancreatic juice induced by neurotensin was increased, but the protein concentration was scarcely changed.3. The neurotensin-induced secretion was inhibited by SCH23390, a dopamine D-1 antagonist, but not by domperidone, phentolamine, propranolol, atropine, cimetidine, or L-364,718, a CCK antagonist.4. Intra-arterial (i.a.) injections of neurotensin (0.1-3 nmol/kg) also elicited dose-dependent increases in the secretory rate of pancreatic juice flow, but did not change bicarbonate or protein concentration. The secretory activities were less effective and 1 nmol/kg of neurotensin i.a. was approximately equal to that of 0.03 nmol/kg of neurotensin i.v.5. These results suggest that neurotensin mainly stimulates pancreatic secretion by acting indirectly. Neurotensin-induced secretion is, at least in part, mediated by endogenously released dopamine which activates dopamine D-1 receptors on the pancreas. In addition to its indirect action, neurotensin has a weak direct action to stimulate pancreatic secretion.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 21 (1994), S. 0 
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. The effects of the cyclic nucleotide phosphodiesterase (PDE) inhibitors, Ro20,1724, 3-isobutyl-1-methylxanthine (IBMX), trifluoperazine (TFP) and amrinone on pancreatic exocrine secretion were investigated in anaesthetized dogs in comparison with those of secretin and cholecystokinin octapeptide (CCK-8).2. Ro20,1724 (1–30 nmol/kg), IBMX (3–30 nmol/kg), secretin (0.01–0.1 pmol/kg) or CCK-8 (0.1–1 pmol/kg) injected i.a. elicited a dose-dependent increase in the secretion of pancreatic juice, but TFP and amrinone (up to 1 μmol/ kg) did not.3. The bicarbonate concentration in pancreatic juice was increased and the protein concentration was decreased by Ro20,1724, IBMX and secretin. Cholecystokinin octapeptide increased the protein concentration but did not alter the bicarbonate concentration.4. Ro20,1724 and IBMX elicited more than the respective additive secretory response when added together with secretin, although the stimulatory effects of CCK-8 with Ro20,1724 and IBMX were additive.5. Ro20,1724 and IBMX increased cyclic AMP concentration but did not affect cyclic GMP concentration.6. These results suggest that Ro20,1724 and IBMX have secretory properties on pancreatic exocrine glands of the dog, which may be mediated through an increase in cyclic AMP subsequent to inhibition of PDE activity. Furthermore, pancreatic PDE enzymes in the dog may be mainly type IV.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 20 (1993), S. 0 
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. The effects of peptide histidine isoleucine (PHI) on pancreatic exocrine secretion were investigated in preparations of the isolated and blood-perfused dog pancreas as compared with those of vasoactive intestinal peptide (VIP), secretin and glucagon.2. Each peptide tested was injected intra-arterially (i.a.) as a single bolus. Graded doses of PHI (3–300 nmol/kg), VIP (1–100 nmol/kg) and secretin (0.01–0.3 nmol/kg) caused dose-dependent increases in the secretion of pancreatic juice and bicarbonate outputs, but had little effect on the protein outputs. Glucagon (0.1–10 μmol/kg) produced a bell-shaped dose—response curve for the secretory rate, bicarbonate and protein outputs.3. The secretory activity of 30 nmol/ kg of PHI corresponded roughly to that of 80 pmol/ kg of secretin, 9 nmol/kg of VIP and 0.6 μmol/kg of glucagon, respectively. Thus, based on administered dose, PHI was about 375 × less potent than secretin, 3 × less potent than VIP and 20 × more potent than glucagon.4. The PHI- and VIP-stimulated secretions were inhibited by a VIP antagonist, but not by a glucagon antagonist, SCH23390 (a dopamine D-1 antagonist), L-364718 (a cholecystokinin antagonist) or atropine.5. Each peptide increased cyclic AMP concentration, but not cyclic GMP concentration, concomitant with the increase in pancreatic secretion.6. From these results, it is concluded that PHI produces an increase in pancreatic secretion by acting on VIP-preferring receptors on the exocrine pancreatic gland of the dogs. This may be mediated at least in part through the increase of intracellular cyclic AMP concentrations.
    Type of Medium: Electronic Resource
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