Culture duration and conditions affect the oscillations of cytoplasmic calcium concentration induced by glucose in mouse pancreatic islets.
The pattern of the increase in cytoplasmic Cai2+ that glucose produces in beta cells has been reported to be highly variable. Here, we evaluated the influence of the culture duration (1-4 days) and conditions (5-10 mmol/l glucose) on Cai2+ in normal mouse islets stimulated by glucose. After 1 day of culture in 10 mmol/l glucose, a rise of the glucose concentration from 3 to 15 mmol/l induced a triphasic change of Cai2+ in the islets. A small initial decrease was followed by a large peak increase and then by regular fast oscillations (approximately 2.5/min). When the culture was prolonged to 2, 3 and 4 days, the initial decrease became inconsistent and the peak occurred earlier, whereas the oscillations decreased in frequency, increased in duration and eventually disappeared; on day 4 the Cai2+ rise was sustained. After culture in 5 mmol/l glucose, the pattern of Cai2+ changes induced by 15 mmol/l glucose was different. The initial decrease was very pronounced, the first peak was delayed and clearly separated from the subsequent oscillations. These were of a mixed type (fast Ca2+ transients on top of slow ones) after 1 day, and of a slow type only after 4 days. These alterations in the Cai2+ oscillations triggered by glucose could not be ascribed to desynchronization of the signal between different regions of the islets. In conclusion, culturing normal mouse islets in 5 or 10 mmol/l glucose for 1-4 days, markedly alters the characteristics of the changes in Cai2+ produced by glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
Unité d'Endocrinologie et Métabolisme, University of Louvain Faculty of Medicine, Brussels, Belgium.
P
P
Gilon
J C
JC
Jonas
J C
JC
Henquin
D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D013997:Time Factors
D005947:Glucose; D002118:Calcium