Dual effect of glucose on cytoplasmic Ca2+ in single pancreatic beta-cells.
The cytoplasmic Ca2+ concentration (Ca2+i) was measured in single pancreatic beta-cells from ob/ob-mice using the fluorescent indicator fura-2. Raising the glucose concentration from 3 to 20 mM resulted in 25% initial lowering of Ca2+i, followed by 250% rise above the basal level of 49 +/- 3 nM. Tolbutamide (100 microM) was as effective as glucose in increasing Ca2+i, although its action was more rapid and not preceded by any reduction. The results support the concept that stimulated removal of Ca2+ from the cytoplasm is an essential part of the physiological glucose effect on the pancreatic beta-cells.
Grapengiesser
E
E
Department of Medical Cell Biology, Uppsala University, Sweden.
Gylfe
E
E
Hellman
B
B
D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D005456:Fluorescent Dyes; D016257:Fura-2; D005947:Glucose / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008820:Mice, Obese; D008856:Microscopy, Fluorescence; D014044:Tolbutamide / Q000494:pharmacology
D001572:Benzofurans; D005456:Fluorescent Dyes; D014044:Tolbutamide; D005947:Glucose; D002118:Calcium; D016257:Fura-2