Abstract：
Metabolic changes are critical in the regulation of Ca2+ influx in central and peripheral neuroendocrine cells. To study the regulation of L-type Ca2+ channels by AMPK we used biochemical reagents and ATP/glucose-concentration manipulations in rat chromaffin cells. AICAR and Compound-C, at low concentration, significantly induce changes in L-type Ca2+ channel-current amplitude and voltage dependence. Remarkably, an overlasting decrease in the channel-current density can be induced by lowering the intracellular level of ATP. Accordingly, Ca2+ channel-current density gradually diminishes by decreasing the extracellular glucose concentration. By using immunofluorescence, a decrease in the expression of CaV1.2 is observed while decreasing extracellular glucose, suggesting that AMPK reduces the number of functional Ca2+ channels into the plasma membrane. Together, these results support for the first time the dependence of metabolic changes in the maintenance of Ca2+ channel-current by AMPK. They reveal a key step in Ca2+ influx in secretory cells.
摘要：
代谢变化在调节中枢和外周神经内分泌细胞中的Ca2流入中至关重要。为了研究AMPK对L型Ca2通道的调节，我们使用了生化试剂和大鼠嗜铬细胞中的ATP/葡萄糖浓度操作。AICAR和化合物C，在低浓度下,显著诱导L型Ca2+通道电流振幅和电压依赖性的变化。值得注意的是,可以通过降低ATP的细胞内水平来诱导通道电流密度的重叠降低。因此，通过降低细胞外葡萄糖浓度，Ca2通道电流密度逐渐降低。通过使用免疫荧光，观察到CaV1.2表达的减少，同时细胞外葡萄糖减少，表明AMPK减少了进入质膜的功能性Ca2+通道的数量。一起,这些结果首次支持AMPK维持Ca2通道电流对代谢变化的依赖性。他们揭示了Ca2+流入分泌细胞的关键步骤。
