title: Dual actions of glucagon: direct stimulation and indirect inhibition of dog pancreatic secretion.
abstract: The secretory actions of glucagon on the exocrine pancreas were examined using two kinds of canine preparations. In the isolated and blood-perfused dog pancreas with venous drainage, i.a. injection of glucagon did not inhibit secretin/cholecystokinin-octapeptide (CCK-8)-stimulated pancreatic secretion, but instead dose dependently enhanced both basal and stimulated pancreatic secretion. Glucagon-induced increase of pancreatic secretion was potentiated by 3-isobutyl-1-methylxanthine. In contrast, i.v. bolus injection of glucagon (3 and 10 nmol/kg) first augmented transiently then suppressed secretin/CCK-8-stimulated pancreatic secretion while simultaneously increasing circulating plasma somatostatin immunoreactivity from 14.2 to 214 fmol/ml in anesthetized intact dogs. The inhibition of secretin/CCK-8-stimulated pancreatic secretion and elevation of plasma somatostatin immunoreactivity induced by glucagon were comparable with those due to somatostatin-14. Thus, these results indicate that glucagon stimulates pancreatic secretion directly; the inhibitory action of glucagon is indirect and appears to be related to a rise in the circulating level of somatostatin immunoreactivity.
authors.affiliation: Department of Pharmacology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Horiuchi
authors.forename: K
authors.initials: K
authors.lastname: Iwatsuki
authors.forename: L M
authors.initials: LM
authors.lastname: Ren
authors.forename: T
authors.initials: T
authors.lastname: Kuroda
authors.forename: S
authors.initials: S
authors.lastname: Chiba
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000758:Anesthesia; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D005934:Glucagon / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D010179:Pancreas / Q000187:drug effects / Q000378:metabolism*; D010189:Pancreatic Juice / Q000187:drug effects / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D012633:Secretin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D012844:Sincalide / Q000494:pharmacology; D013004:Somatostatin / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology
chemical_list: D001639:Bicarbonates; D011506:Proteins; D012633:Secretin; D013004:Somatostatin; D005934:Glucagon; D012844:Sincalide; D015056:1-Methyl-3-isobutylxanthine