Regulation of adenosine 3',5'-monophosphate levels in the pancreatic B cell

Endocrinology. 1985 Sep;117(3):834-40. doi: 10.1210/endo-117-3-834.


The poor glucose-induced insulin release from single purified B cells has been attributed, in part, to the low cellular cAMP levels. The present study demonstrates that isolated B cells exhibit a markedly lower cAMP formation than B cells lodged in intact islets and suggest that this deficiency is caused by their separation from glucagon-containing A cells. cAMP levels in purified B cells are rapidly and potently elevated by glucagon from 10(-10) M on, reaching the values of islet B cells at 10(-9) M. In contrast, exogenous glucagon stimulates cAMP formation in isolated islets only from 3.10(-9) M on, suggesting that endogenously released glucagon is mainly responsible for the higher cAMP levels in islet B cells. Somatostatin counteracts glucagon-induced cAMP production in purified B cells and, therefore, has also the potential to mediate an intra-islet regulation of B cell functions. Neither insulin nor pancreatic polypeptide affect cAMP formation in pancreatic B cells. Glucose alone does not influence cAMP levels in purified B cells, but enhances glucagon-induced cAMP formation in these cells. The glucose-dependent increase in islet cAMP is therefore not considered as the nutrient-induced mediator for hormone release but as a minor amplification of the glucagon-dependent signal. Experiments on reaggregated islet cells permit the reconstruction of the events which regulate cAMP levels in isolated islets. Further support is hereby given to the hypothesis that a normal glucose-induced insulin release from intact islets requires the simultaneous synarchic participation of a nutrient-dependent and a hormone-dependent messenger system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Animals
  • Cyclic AMP / metabolism*
  • Dose-Response Relationship, Drug
  • Glucagon / pharmacology
  • Glucose / pharmacology
  • In Vitro Techniques
  • Insulin / pharmacology
  • Islets of Langerhans / cytology
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / metabolism*
  • Male
  • Pancreatic Polypeptide / pharmacology
  • Rats
  • Rats, Inbred Strains
  • Somatostatin / pharmacology


  • Insulin
  • Somatostatin
  • Pancreatic Polypeptide
  • Glucagon
  • Cyclic AMP
  • Glucose
  • 1-Methyl-3-isobutylxanthine