Phosphate flush and glucose metabolism in pancreatic islets of young and old diabetic mice (C57BL/KsJ-db/db).
Pancreatic islets from normal C57BL/KsJ-+/+-mice and diabetic C57BL/KsJ-db/db-mice were collagenase-isolated and incubated with 33P-labelled inorganic phosphate. No significant difference was observed in phosphate uptake between normal and diabetic mouse islets whether the animals were young (6-8 weeks) or old (27 +/- 9 weeks). When 33P-labelled islets were perifused with non-radioactive medium, all types of islets exhibited a brisk and transient peak of phosphate release in response to a change of glucose concentration from 2.8 to 16.7 mmol/l. Expressed in absolute terms, both the basal and peak efflux of phosphate appeared to be diminished in the diabetic mice. In relative terms (peak over basal), the glucose-stimulated phosphate efflux was not lower in diabetic than in normal mice. At both a low (3 mmol/l) and a high (20 mmol/l) glucose concentration, the production of 3H2O from D-[5-3H]glucose was reduced in old but not in young diabetic mouse islets. The percentage increase in glucose metabolism in response to a rise in glucose concentration from 3 to 20 mmol/l was about the same in all types of islets. The results add to previous observations of disturbed ionic fluxes in the pancreatic islets of diabetic KsJ-db/db-mice. These effects are probably not due to gross alterations in glycolytic metabolism but more probably reflect alterations in the function of the beta-cell plasma membrane.
D000367:Age Factors; D000818:Animals; D001834:Body Water / Q000378:metabolism; D002463:Cell Membrane Permeability; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D010477:Perfusion; D010710:Phosphates / Q000378:metabolism*
D007328:Insulin; D010710:Phosphates; D005947:Glucose