FUNCTIONAL-SIGNIFICANCE OF CA2-CELLS( OSCILLATIONS IN PANCREATIC BETA)

Several aspects of pancreatic beta cell function display marked oscill ations even during continuous stimulation with a stable glucose concen tration. This review article focuses on the characteristics, mechanism s and potential roles of the oscillations of cytoplamic Ca2+ concentra tion ([Ca2+](i)) in beta cells. These oscillations result from an inte rmittent influx of Ca2+ through voltage-dependent Ca2+ channels activa ted by periodic depolarizations of the plasma membrane. in each islet, [Ca2+](i) oscillations are synchronous in ail beta cells and trigger similar oscillations of insulin secretion. Changes in [Ca2+](i) are th ought 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 c ell itself or are simply necessary to ensure oscillations of plasma in sulin levels through pulsatile secretion of the hormone.