ISSN:
1432-0428
Keywords:
Glucose
;
cytoplasmic Ca2+ balance
;
β cells
;
insulin release
;
depolarization
;
intracellular Ca2+ sequestration
;
diabetes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The introduction of new techniques and the access to clonal lines of insulin-secreting cells have enabled re-evaluation of glucose effects on Ca2+ movements in pancreatic β cells. It became evident that glucose, in addition to stimulating the entry of Ca2+ also promotes active sequestration of the ion in intracellular stores and its extrusion from the β cells. The balance between these processes will determine the activity of Ca2+ in the cytoplasm and consequently the rate of insulin release. With the demonstration that glucose can not only increase but also lower cytoplasmic Ca2+, it follows that exposure to the sugar under certain conditions results in a paradoxical inhibition of insulin release. In diabetic patients this may be manifest as prompt reduction of circulating concentrations of insulin and C-peptide after an intravenous injection of glucose. The concept of the dual action of glucose might aid in explaining a number of poorly understood phenomena, such as the induction of rhythmic oscillations of the membrane potential of β cells and the fact that their secretory response is improved by prolonged exposure to glucose and after priming with the sugar.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00281983
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