Gastrin releasing peptide augments glucose mediated 45Ca2+ uptake, electrical activity, and insulin secretion of mouse pancreatic islets.
Gastrin releasing peptide (GRP) has recently been shown to increase glucose-induced insulin secretion in vivo. Being present in pancreatic tissue, the 27-amino acid peptide could play a role in the control of the glucose-induced insulin secretion of islets of Langerhans. In the presence of a stimulatory glucose concentration, GRP augmented insulin secretion of isolated islets in batch incubations. The peptide did not affect 56Rb+ efflux in the presence of 3 or 5.6 mM glucose but reduced the increase of 86Rb+ efflux evoked by the calcium ionophore A23187. 45Ca2+ uptake and intracellular recorded electrical activity induced by glucose were amplified by GRP. It is suggested that GRP plays a role in the regulation of glucose-induced insulin secretion by increasing the uptake of Ca2+ directly or by inhibition of the Ca(2+)-dependent K+ channel activity and reduced repolarization of the cell.
Wahl
M A
MA
Department of Pharmacology, Eberhard-Karls Universität Tübingen, Federal Republic of Germany.
Plehn
R J
RJ
Landsbeck
E A
EA
Verspohl
E J
EJ
Ammon
H P
HP
D000818:Animals; D002118:Calcium / Q000493:pharmacokinetics*; D002132:Calcium Radioisotopes; D004594:Electrophysiology; D019886:Gastrin-Releasing Peptide; D005768:Gastrointestinal Hormones / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D010455:Peptides / Q000494:pharmacology*; D012413:Rubidium / Q000378:metabolism
D002132:Calcium Radioisotopes; D005768:Gastrointestinal Hormones; D007328:Insulin; D010455:Peptides; D019886:Gastrin-Releasing Peptide; D005947:Glucose; D012413:Rubidium; D002118:Calcium