Extracellular Ca2+ induces a rapid increase in cytoplasmic free Ca2+ in pancreatic beta-cells.
Using pancreatic beta-cells isolated from obese hyperglycemic mice, it was demonstrated that the addition of 5 mM extracellular Ca2+ evoked a rapid and transient increase in cytoplasmic free Ca2+ concentration ([Ca2+]i). The effect remained in the presence of D-600. Extracellular Ca2+ did not raise [Ca2+]i subsequent to emptying the inositol 1,4,5-trisphosphate (InsP3) sensitive pool by carbamylcholine stimulation, indicating that the pool released by extracellular Ca2+ is of similar origin. Stimulation with extracellular Ca2+ was accompanied by a pronounced insulin release. Our results suggest that the Ca2+-induced rise in [Ca2+]i is mediated through the formation of InsP3, a mechanism that might operate also in other types of cells.
D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D002413:Cations, Divalent; D003593:Cytoplasm / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D005711:Gallopamil / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D051379:Mice; D008820:Mice, Obese; D013324:Strontium / Q000494:pharmacology
D002413:Cations, Divalent; D007328:Insulin; D007473:Ion Channels; D001464:Barium; D005711:Gallopamil; D002217:Carbachol; D008274:Magnesium; D005947:Glucose; D002118:Calcium; D013324:Strontium