The endoplasmic reticulum as one continuous Ca2+ pool:: visualization of rapid Ca2+ movements and equilibration
The endoplasmic reticulum as one continuous Ca2+ pool:: visualization of rapid Ca2+ movements and equilibration
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DOI：
10.1093/emboj/19.21.5729
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发表时间：
2000-11-01
期刊：
影响因子：
11.4
通讯作者：
Tepikin, AV
中科院分区：
文献类型：
--
作者：
Park, MK;Petersen, OH;Tepikin, AV
我们通过共聚焦显微镜、局部漂白和释放技术，观察了胰腺腺泡细胞内质网（ER）腔内Ca ~（2+）和小荧光探针的动态变化，研究了ER是一个功能上相互连接的Ca ~（2+）库还是由不同的亚基组成。ER基部的大部分没有与顶部的颗粒相连，但扩散到小的顶部ER延伸中。ER Ca 2+储存的连接性很强，因为即使是超最大的乙酰胆碱（ACh）刺激30分钟也不会导致功能断裂。ACh可引起整个细胞内ER Ca ~（2+）浓度的均匀降低，但低浓度ACh引起的胞浆Ca ~（2+）峰电位几乎不降低ER Ca ~（2+）水平。我们认为ER是一个功能连续的单位，它能有效地释放Ca ~（2+），从顶端释放的Ca ~（2+）很快从基部的粗面ER中得到补充。
We investigated whether the endoplasmic reticulum (ER) is a functionally connected Ca2+ store or is composed of separate subunits by monitoring movements of Ca2+ and small fluorescent probes in the ER lumen of pancreatic acinar cells, using confocal microscopy, local bleaching and uncaging, We observed rapid movements and equilibration of Ca2+ and the probes. The bulk of the ER at the base was not connected to the granules in the apical part, but diffusion into small apical ER extensions occurred, The connectivity of the ER Ca2+ store was robust, since even supramaximal acetylcholine (ACh) stimulation for 30 min did not result in functional fragmentation. ACh could elicit a uniform decrease in the ER Ca2+ concentration throughout the cell, but repetitive cytosolic Ca2+ spikes, induced by a low ACh concentration, hardly reduced the ER Ca2+ level, We conclude that the ER is a functionally continuous unit, which enables efficient Ca2+ liberation, Ca2+ released from the apical ER terminals is quickly replenished from the bulk of the rough ER at the base.