Effects of various modifiers of insulin release on the lanthanum-nondisplaceable 45Ca2+ uptake by isolated pancreatic islets.
The uptake of 45Ca2+ by a lanthanum-non-displaceable pool in pancreatic islets was studied; Raising the extracellular D-glucose concentration from 3 to 20 mM stimulated the 45Ca2+ uptake in hand-dissected islets of ob/bo-mice as well as in collagenase-isolated islets of ob/ob or normal mice. The effect was dose-dependent in the range of 0-20 mM D-glucose and was seen throughout a wide range of extracellular calcium concentrations (16 mumol-2.56 mmol of Ca2+ added per litre of medium). The 45Ca2+ uptake was also enhanced by other known insulin secretagogues (D-mannose, L-leucine, tolbutamide) and was uninfluenced by compounds lacking insulin-releasing capacity (3-O-methyl-D-glucose, L-glucose, D-galactose, D-leucine). The stimulatory effect of D-glucose was blocked by inhibitors of glucose-induced insulin release (D-mannoheptulose, diazoxide, L-adrenaline). The results support the view that the lanthanum-nondisplaceable calcium pool is related to the insulin-releasing mechanism, although the exact nature of this relationship is still unclear.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D007811:Lanthanum; D051379:Mice; D008820:Mice, Obese; D003012:Microbial Collagenase
D007328:Insulin; D007811:Lanthanum; D003012:Microbial Collagenase; D005947:Glucose; D002118:Calcium