Bergsten P
Department of Medical Cell Biology, Biomedicum, Uppsala University, Sweden.
Am J Physiol. 1998 May;274(5):E796-800. doi: 10.1152/ajpendo.1998.274.5.E796.
The cytoplasmic Ca2+ concentration ([Ca2+]i) and insulin release were measured simultaneously in mouse pancreatic islets cultured overnight. [Ca2+]i was 105 nM and insulin release 3 pmol.g-1.s-1 at 3 mM glucose. An increase to 7 mM glucose reduced [Ca2+]i transiently, whereas insulin release doubled and was pulsatile with a frequency of 0.47 min-1. [Ca2+]i oscillations with similar frequency appeared at 11 mM glucose associated with increased amplitude of the insulin oscillations, raising the secretory rate 10-fold. In the presence of 16 and 20 mM glucose [Ca2+]i was > 300 nM and showed no oscillations apart from two islets, which demonstrated [Ca2+]i oscillations with small amplitude at 16 mM glucose. Insulin release with maintained frequency increased by 46 and 31%, respectively. When the glucose concentration was increased from 3 to 11 mM, [Ca2+]i decreased with a nadir that appeared significantly earlier than when the glucose concentration was raised from 3 to 7 mM. Glucose-induced insulin release from the isolated islet is pulsatile both at stable and oscillatory [Ca2+]i, with changes in secretory rate caused by the sugar also when [Ca2+]i is unchanged.
对过夜培养的小鼠胰岛同时测量细胞质钙离子浓度（[Ca2+]i）和胰岛素释放量。在3 mM葡萄糖浓度下，[Ca2+]i为105 nM，胰岛素释放量为3 pmol·g-1·s-1。葡萄糖浓度增加到7 mM时，[Ca2+]i短暂降低，而胰岛素释放量增加一倍且呈搏动性，频率为0.47 min-1。在11 mM葡萄糖浓度下出现频率相似的[Ca2+]i振荡，同时胰岛素振荡幅度增加，分泌速率提高10倍。在16和20 mM葡萄糖浓度下，除两个胰岛外，[Ca2+]i> 300 nM且无振荡，这两个胰岛在16 mM葡萄糖浓度下显示出小幅度的[Ca2+]i振荡。胰岛素释放频率维持不变，分别增加了46%和31%。当葡萄糖浓度从3 mM增加到11 mM时，[Ca2+]i下降，最低点出现的时间明显早于葡萄糖浓度从3 mM增加到7 mM时。在稳定和振荡的[Ca2+]i条件下，葡萄糖诱导的离体胰岛胰岛素释放均呈搏动性，即使[Ca2+]i不变，糖也会引起分泌速率的变化。
