Glucose-induced oscillations of cytoplasmic Ca2+ in the pancreatic beta-cell.
The cytoplasmic calcium concentration (Ca2+i) was measured in individual mouse pancreatic beta-cells loaded with fura-2 by recording the 340/380 nm fluorescence excitation ratio. An increase of the glucose concentration from 3 to 20 mM, caused initial lowering of Ca2+i followed by a rise with a peak preceding constant elevation at an intermediary level. However, at 11 mM glucose there were large Ca2+i oscillations with a frequency of 1 cycle per 2-6 min. The results indicate that both first and second phase secretion depend on elevated Ca2+i, and that many electrically coupled cells collectively determine the pace of rhythmic depolarization.
Grapengiesser
E
E
Department of Medical Cell Biology, Uppsala University, Sweden.
Gylfe
E
E
Hellman
B
B
D000818:Animals; D001572:Benzofurans; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism*; D016257:Fura-2; D005947:Glucose / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008820:Mice, Obese
D001572:Benzofurans; D005947:Glucose; D016257:Fura-2