These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Sustained oscillations of insulin, glucagon, and somatostatin from the isolated canine pancreas during exposure to a constant glucose concentration.
    Author: Stagner JI, Samols E, Weir GC.
    Journal: J Clin Invest; 1980 Apr; 65(4):939-42. PubMed ID: 6987271.
    Abstract:
    Canine pancreata were perfused in vitro to examine whether hormone cycles could be demonstrated without hepatic or central nervous influence. Insulin, glucagon, and somatostatin demonstrated regular sustained cyclic secretion from the in vitro canine pancreas. Oscillations were noted for over 200 min during the infusion of a constant glucose concentration. Insulin demonstrated a 10-min period with a range of 8-12 min/cycle. Somatostatin had a 10-min period with a range of 8-11 min. Glucagon had a period of 8.6 min with range of 6-10 min. These periods do not allow glucagon to be consistently 90 degrees out of phase with insulin and somatostatin. When glucose was increased from 88 to 200 mg/dl, insulin cycles persisted but on an elevated base line, demonstrating that cycles react to glucose changes but are not dependent upon them. Cycles were disrupted by infusions of dopamine, apomorphine, epinephrine, and acetylcholine, but were reestablished. Autonomic blockade by both single and combined infusions of atropine (cholinergic), propranolol, and dibenzyline (adrenergic) had no effect on cycles. These results suggest that, in vitro, there is an intrinsic rhythm of hormone secretion by the pancreas despite a constant glucose level. The production of in vitro cycles requires the presence of a driving oscillator or pacemaker within the pancreas and the coordination of islets by pace-maker-islet communication, presumably by a non-adrenergic neural system. In vitro oscillations may Indicate that the pancreas is the driver or Zeitgeber of in vivo glucose-insulin cycles.
    [Abstract] [Full Text] [Related] [New Search]