Dual effects of glucose on the cytosolic Ca2+ activity of mouse pancreatic beta-cells.
The cytosolic Ca2+ activity of mouse pancreatic beta-cells was studied with the intracellular fluorescent indicator quin2 . When the extracellular Ca2+ concentration was 1.20 mM, the basal cytosolic Ca2+ activity was 162 +/- 9 nM. Stimulation with 20 mM glucose increased this Ca2+ activity by 40%. In the presence of only 0.20 mM Ca2+ or after the addition of the voltage-dependent Ca2+ -channel blocker D-600, glucose had an opposite and more prompt effect in reducing cytosolic Ca2+ by about 15%. It is concluded that an early result of glucose exposure is a lowering of the cytosolic Ca2+ activity and that this effect tends to be masked by a subsequent increase of the Ca2+ activity due to influx of Ca2+ through the voltage-dependent Ca2+ channels.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005260:Female; D005711:Gallopamil / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008820:Mice, Obese; D013050:Spectrometry, Fluorescence
D005711:Gallopamil; D005947:Glucose; D002118:Calcium