Gastric inhibitory polypeptide and splanchnic blood perfusion: Augmentation of the islet blood flow increase in hyperglycemic rats

The aim of the study was to investigate how the incretin candidate hormone gastric inhibitory polypeptide (GIP) affects splanchnic blood how, especially pancreatic islet blood flow. For this purpose, male Sprague-Dawley rats were injected intravenously with either saline or GIP (5 or 15 mu g/kg body weight) 10 min before blood flow measurements by a microsphere technique. Furthermore, 3 min before the blood how measurements, 1 mi of either saline or 30% D-glucose was given intravenously. All glucose-injected animals were markedly hyperglycemic (>20 mmol/liter) at the time of the blood how measurements. Both doses of GIP potentiated basal and glucose-stimulated insulin release. In the normoglycemic rats, the lowest dose of GIP did not affect the blood perfusion to any of the investigated organs. The highest dose of GTP decreased whole pancreatic and duodenal blood how, whereas islet blood how was unaffected. As a result, fractional islet blood flow was increased. In the hyperglycemic rats, where the islet blood flow was increased compared with control animals, both doses of GLP further enhanced islet blood how. No effect on pancreatic, fractional islet, or duodenal blood flow was seen after GIP administration to hyperglycemic animals. It is concluded that administration of GIP can further augment the glucose-induced stimulation of islet blood flow. This map contribute to facilitating release of insulin from the islets. (C) 1997 Elsevier Science Inc.