Timing of Ca2+ response in pancreatic beta-cells is related to mitochondrial mass.
The timing and magnitude of calcium response are cell-specific in individual beta-cells. This may indicate that the cells have different roles in the intact islet. It is unknown what mechanisms determine these characteristics. We previously found that the mechanisms setting cell-specific response timing are disturbed in beta-cells from hyperglycemic mice and one of the causes is likely to be an altered mitochondrial metabolism. Mitochondria play a key role in the control of nutrient-induced insulin secretion. Here, we used confocal microscopy with the fluorescent probe MitoTracker Red CMXRos and Fluo-3 to study how the amount of active mitochondria is related to the lag-time and the magnitude of calcium response to 20mM glucose in isolated beta-cells and in cells within intact lean and ob/ob mouse islets. Results show that the mitochondrial mass is inversely correlated with the lag-times for calcium response both in lean and ob/ob mouse beta-cells (r=-0.73 and r=-0.43, respectively, P<0.05). Thus, the state of mitochondria may determine the timing of calcium response.
Gustavsson
N
N
Department of Integrative Medical Biology, Section for Histology and Cell Biology, Umeå University, Umeå, Sweden. natalia.gustavsson@histocel.umu.se
Abedi
G
G
Larsson-Nyrén
G
G
Lindström
P
P
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D051379:Mice; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure*
D005947:Glucose; D002118:Calcium