SINGLE ISLET BETA-CELL STIMULATION BY NUTRIENTS - RELATIONSHIP BETWEEN PYRIDINE-NUCLEOTIDES, CYTOSOLIC CA2+ AND SECRETION
SINGLE ISLET BETA-CELL STIMULATION BY NUTRIENTS - RELATIONSHIP BETWEEN PYRIDINE-NUCLEOTIDES, CYTOSOLIC CA2+ AND SECRETION
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DOI：
10.1002/j.1460-2075.1990.tb08079.x
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发表时间：
1990-01-01
期刊：
影响因子：
11.4
通讯作者：
WOLLHEIM, CB
中科院分区：
文献类型：
--
作者：
PRALONG, WF;BARTLEY, C;WOLLHEIM, CB
人们普遍认为，营养刺激引发胰岛素分泌需要产生代谢耦合因子，导致膜去极化和电压敏感Ca2+通道的门控。为了建立该事件序列，将反映营养物代谢的还原吡啶核苷酸[NAD(P)H]的内源荧光动力学与单个培养的大鼠岛β-细胞中胞质钙([Ca2+]i)升高的动力学进行比较。在初步实验中，预标记细胞中奎纳克林荧光的丧失被用作分泌的指标。这种染料浓缩在含有胰岛素的酸性分泌颗粒中。葡萄糖和 2-酮异己酸 (KIC) 均以剂量依赖性方式升高 [Ca2+]i。 [Ca2+]1i 反应模式存在明显的细胞异质性。这两种营养刺激也增加了 NAD(P)H 荧光，再次显示出细胞间的差异。在组合实验中，在同一细胞中测量两个参数，NAD(P)H 荧光的升高先于 [Ca2+]i 的升高，证实了对单独细胞进行的统计评估。连续两次葡萄糖激发的应用揭示了 [Ca2+]i 和 NAD(P)H 荧光的协调变化。最后，两种营养素刺激奎纳克林分泌，其起效时间与 [Ca2+]i 升高记录的起效时间相似。这些结果清楚地表明，在 Ca2+ 通过电压敏感 Ca2+ 通道流入之前的滞后期内，新陈代谢发生增加，这是营养刺激触发胰岛素分泌的先决条件。
It is generally believed that the initiation of insulin secretion by nutrient stimuli necessitates the generation of metabolic coupling factor, leding to membrane depolarization and the gating of voltage-sensitive Ca2+ channels. To establish this sequence of events, the kinetics of endogenous fluorescence of reduced pyridine nucleotides [NAD(P)H], reflecting nutrient metabolism, were compared to those of cytosolic calcium ([Ca2+]i) rises in single cultured rat isle .beta.-cells. In preliminary experments, the loss of quinacrine fluorescence from prelabelled cells was used as an indicator of secretion. This dye is concentrated in the acidic insulin-containing secretory granules. Both glucose and 2-ketoisocaproate (KIC) raised [Ca2+]i in a dose-dependent manner. There was marked cellular heterogeneity in the [Ca2+]1i response patterns. The two nutrient stimuli also increased NAD(P)H fluorescence, again showing cell-to-cell variations. In combined experiments, where the two parameters were measured in the same cell, the elevation of the NAD(P)H fluorescence preceded the rise in [Ca2+]i, confirming the statistical evaluation performed on separate cells. The application of two consecutive glucose challenges revealed coordinated changes in [Ca2+]i and NAD(P)H fluorescence. Finally, quinacrine secretion was stimulated by two nutrients with onset times similar to those recorded for [Ca2+]i elevations. These results clearly demonstrate that increased metabolism occurs during the lag period preceding Ca2+ influx via voltage-sensitive Ca2+ channels, a prerequisite for the triggering of insulin secretion by nutrient stimuli.