Glucagon in Perfused Rat Pancreas
نویسندگان
چکیده
The biosynthesis of glucagon was studied by using the recirculated, isolated perfused rat pancreas. [3H]Tryptophan was initially incorporated into acid-ethanol-extractable protein, which on gel filtration was eluted with a molecular weight ofabout 9000 and contained a small amount of glucagon immunoreactivity. With longer incubation [3H]tryptophan incorporation into a second peak was obtained in an identical position with that of the majority of rat glucagon immunoreactivity. This peak of labelled protein exhibited migration characteristics on polyacrylamide-gel electrophoresis identical with those of rat glucagon and was identified as newly synthesized glucagon by demonstration ofspecific binding and dissociation behaviour with glucagon antibodies. The incorporation of [3H]tryptophan into acid-ethanol-extractable protein was inhibited by cycloheximide. High concentrations of glucose increased [3H]tryptophan incorporation into highmolecular-weight protein but decreased incorporation into proteins smaller than cytochrome c. The pattern of [3H]leucine incorporation into protein was similar to that of [3H]tryptophan.
منابع مشابه
Adrenergic modulation of insulin and glucagon secretion from the isolated perfused rat pancreas.
In order to observe the effect of the adrenergic system on pancreatic glucagon secretion in the isolated perfused rat pancreas, phenylephrine, an alpha-adrenergic agonist, and isoproterenol, a beta-adrenergic agonist, were added to the perfused solution. 1.2 microM phenylephrine suppressed glucagon secretion at 2.8 mM glucose, and it also decreased insulin secretion at 11.1 mM glucose. 240 nM i...
متن کاملAssessment of the Role of Interstitial Glucagon in the Acute Glucose Secretory Responsiveness of In Situ Pancreatic -Cells
Glucagon is a potent stimulator of insulin release in the presence of a permissive glucose concentration, activating -cells in vitro via both glucagonand glucagon-like peptide-1 (GLP-1)–receptors. It is still unclear whether locally released glucagon amplifies the secretory responsiveness of neighboring -cells in the intact pancreas. The present study investigates this question in the perfused ...
متن کاملInsulinotropin: glucagon-like peptide I (7-37) co-encoded in the glucagon gene is a potent stimulator of insulin release in the perfused rat pancreas.
Insulin secretion is controlled by a complex set of factors that include not only glucose but amino acids, catecholamines, and intestinal hormones. We report that a novel glucagon-like peptide, co-encoded with glucagon in the glucagon gene is a potent insulinotropic factor. The glucagon gene encodes a proglucagon that contains in its sequence glucagon and additional glucagon-like peptides (GLPs...
متن کاملEffect of glucose/sulfonylurea interaction on release of insulin, glucagon, and somatostatin from isolated perfused rat pancreas.
The effect of a sulfonylurea, glibenclamide, on the release of insulin, glucagon, and somatostatin was studied in the isolated perfused rat pancreas. At glucose concentrations of 1.1 mM or less, the drug stimulated somatostatin release, whereas glucagon release, after 2-3 min of increase, was markedly inhibited. Insulin release was moderately stimulated, and maximal release occurred relatively ...
متن کاملGlucagon secretion from the perfused rat pancreas. Studies with glucose and catecholamines.
The isolated in situ perfused rat pancreas was used to study glucose and catecholamine control of glucagon secretion, and to investigate the possible role of endogenous cyclic AMP as a mediator of this secretory process. When perfusate glucose was acutely dropped from 100 to 25 mg/100 ml, glucagon was released in a biphasic pattern with an early spike and a later plateau-like response. 300 mg/1...
متن کامل