title: Effect of GIP on the secretion of insulin and somatostatin and the accumulation of cyclic AMP in vitro in the rat.
abstract: The effects of gastric inhibitory polypeptide (GIP) on insulin secretion as well as on the intra-islet accumulation of [3H]cyclic AMP were investigated in isolated pancreatic islets of the rat. In the presence of 6.7 mmol/l of glucose, 3.0 and 30 nmol/l of GIP induced both insulin and [3H]cyclic AMP responses, while lower and higher concentrations of the peptide were ineffective. A coupling of the two parameters was also found with regard to interaction between glucose and GIP. Thus while 30 nmol/l of GIP was stimulatory together with 6.7, 16.7 or 33.3 mmol/l of glucose, the peptide stimulated neither insulin release, nor the accumulation of [3H]cyclic AMP in the presence of a low concentration of glucose (3.3 mmol/l). The concomittant release of insulin and somatostatin was studied in the perfused pancreas in order to assess a possible influence by somatostatin on the dose-response pattern for GIP-induced insulin release. In this preparation 1.0 to 10 nmol/l of GIP stimulated insulin and somatostatin secretion; however while these concentrations were equipotent on insulin release, 10 nmol/l of GIP stimulated somatostatin release more than 1 nmol/l, indicating differences in dose-response curves for the GIP-induced stimulation of the two hormones. It is concluded that 1) modulation of GIP-induced insulin release is coupled to changes in cyclc AMP response in the islet, 2) GIP-induced somatostatin secretion may influence the concomittant insulin response.
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005749:Gastric Inhibitory Polypeptide / Q000494:pharmacology*; D005768:Gastrointestinal Hormones / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism; D008297:Male; D010179:Pancreas / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000378:metabolism*
chemical_list: D005768:Gastrointestinal Hormones; D007328:Insulin; D013004:Somatostatin; D005749:Gastric Inhibitory Polypeptide; D000242:Cyclic AMP; D005947:Glucose