Glucose-stimulated and La3+-nondisplaceable Ca2+ pool in pancreatic islets.
To study intracellular pools of calcium tissue specimens from noninbred ob/ob mice were labeled with 45Ca2+ and subsequently washed with La3+. D-glucose, 20 mM, enhanced the labeling of the La3+-nondisplaceable calcium in pancreatic islets but not in pieces of exocrine pancreas or liver. The disappearance of 45Ca2+ from labeled islets was accelerated by the ionophore, X-537A, but not by dibutyryl cyclic AMP, theophylline, or pentobarbital. On fractionation of 45Ca2+-labeled islets, the greatest radioactivity per unit of protein occured in a fraction rich in insulin secretory granules. The radioactivity of this fraction was higher after the islets had been loaded with 45Ca2+ in the presence of 20 mM glucose as compared to 3 mM glucose. It is concluded that the secretory granules make up a considerable part of the glucose-sensitive calcium store in the beta-cells.
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D007811:Lanthanum; D007832:Lasalocid / Q000494:pharmacology; D008099:Liver / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D010179:Pancreas / Q000378:metabolism; D010424:Pentobarbital / Q000494:pharmacology; D013268:Stimulation, Chemical; D013347:Subcellular Fractions / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology
D003994:Bucladesine; D007811:Lanthanum; D013806:Theophylline; D010424:Pentobarbital; D005947:Glucose; D002118:Calcium; D007832:Lasalocid