title: Cosecretion of islet amyloid polypeptide (IAPP) and insulin from isolated rat pancreatic islets following stimulation or inhibition of beta-cell function.
abstract: The aim of this work was to simultaneously study the secretion of islet amyloid polypeptide (IAPP) and insulin from isolated rat pancreatic islets in vitro. For examination of stimulated beta-cells, nutrient secretagogues (16.7 mM glucose, 10 mM leucine + 2 mM glutamine), phosphodiesterase inhibition (5 mM theophylline), a sulphonylurea (0.5 microgram/ml glipizide), a non-nutrient amino acid (10 mM arginine), cholinergic stimulation (0.1 mM carbamylcholine) and insulinotropic peptides (0.1 microM vasoactive intestinal polypeptide and 0.1 microM glucagon), were used. For beta-cell suppression glucose phosphorylation inhibition (10 mM mannoheptulose), depletion of extracellular calcium, activation of the ATP-regulated K(+)-channel (0.5 mM diazoxide), adrenoreceptor stimulation (3 microM adrenaline), paracrine modulation (0.1 microM somatostatin), short-term treatment with a selective beta-cytotoxin (1.1 and 2.2 mM streptozotocin) and long-term treatment with a cytokine (25 U/ml interleukin-1 beta), were studied. The compounds with known effects on insulin secretion exerted their expected actions and this was paralleled by similar relative changes, with a possible exception for glucagon, in the IAPP secretion. The ratio of IAPP/insulin released did not change significantly under any of the tested experimental conditions, except for a slight increase following carbamylcholine stimulation. On a molar basis approx. 1% of IAPP was released when compared with insulin. These results are consistent with the hypothesis that the regulation of IAPP secretion from beta-cells of isolated rat pancreatic islets is essentially regulated by the same mechanisms as insulin secretion.
authors.affiliation: Department of Clinical Chemistry, Uppsala University, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Stridsberg
authors.forename: S
authors.initials: S
authors.lastname: Sandler
authors.forename: E
authors.initials: E
authors.lastname: Wilander
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D003981:Diazoxide / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007375:Interleukin-1 / Q000494:pharmacology; D058228:Islet Amyloid Polypeptide; D007515:Islets of Langerhans / Q000378:metabolism* / Q000502:physiology; D008297:Male; D008356:Mannoheptulose / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013311:Streptozocin / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D000682:Amyloid; D007328:Insulin; D007375:Interleukin-1; D058228:Islet Amyloid Polypeptide; D009479:Neuropeptides; D013311:Streptozocin; D008356:Mannoheptulose; D002217:Carbachol; D005947:Glucose; D003981:Diazoxide; D002118:Calcium