Functional significance of Ca2+ oscillations in pancreatic beta cells.
Several aspects of pancreatic beta cell function display marked oscillations even during continuous stimulation with a stable glucose concentration. This review article focuses on the characteristics, mechanisms and potential roles of the oscillations of cytoplasmic Ca2+ concentration [(Ca2+]i) in beta cells. These oscillations result from an intermittent influx of Ca2+ through voltage-dependent Ca2+ channels activated by periodic depolarizations of the plasma membrane. In each islet, [Ca2+]i oscillations are synchronous in all beta cells and trigger similar oscillations of insulin secretion. Changes in [Ca2+]i are thought to play a minute-to-minute regulatory role in secretion, but the effectiveness of Ca2+ on the secretory process is markedly influenced by various amplification mechanisms. It is still unclear whether the oscillations of [Ca2+]i reflect functional advantages for the beta cell itself or are simply necessary to ensure oscillations of plasma insulin levels through pulsatile secretion of the hormone.
Henquin
J C
JC
Unité d'Endocrinologie et Métabolisme, Faculty of Medicine University of Louvain, Brussels, Belgium.
Jonas
J C
JC
Gilon
P
P
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism* / Q000648:ultrastructure; D009991:Oscillometry; D012636:Secretory Rate; D015398:Signal Transduction / Q000502:physiology*
D007328:Insulin; D002118:Calcium