Vitamin D3 stimulates calcium-45 uptake by isolated mouse islets in vitro.
Islets isolated from ob/ob mice which had been fed a vitamin D-deficient diet released significantly less insulin in response to glucose than did vitamin D-replete islets but showed normal net 45Ca2+ uptake. To determine whether vitamin D3 has a direct effect on the pancreatic B cell, islets from ob/ob mice on a normal diet were exposed to vitamin D3 in vitro for 1 week or only 3 h, and then glucose-stimulated 45Ca2+ uptake and insulin release were measured. Exposure to 1 nM or 1 microM vitamin D3 for 1 week stimulated 45Ca2+ uptake in the presence of 3 mM, but not 20 mM glucose, and did not affect insulin release. Exposure to vitamin D3 for 3 h did not significantly increase net 45Ca2+ uptake although there was a tendency to such an effect (P = 0.10). In conclusion, vitamin D-deficiency in vivo suppressed subsequent glucose-stimulated insulin release in vitro and this effect may be due to a direct effect of the sterol (or one of its metabolites) on calcium handling by the B cell.
Frankel
B J
BJ
Sehlin
J
J
Täljedal
I B
IB
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002478:Cells, Cultured; D002762:Cholecalciferol / Q000494:pharmacology*; D005260:Female; D007328:Insulin / Q000378:metabolism; D007515:Islets of Langerhans / Q000378:metabolism*; D051379:Mice; D008820:Mice, Obese; D014808:Vitamin D Deficiency / Q000378:metabolism
D002132:Calcium Radioisotopes; D007328:Insulin; D002762:Cholecalciferol; D002118:Calcium