Volume-sensitive Ca influx and release from intracellular pools in gastric parietal cells.
Volume-sensitive Ca influx and release from intracellular pools in gastric parietal cells.
复制标题
胃壁细胞中容量敏感的 Ca 流入和细胞内池释放。
DOI：
10.1152/ajpcell.1992.263.3.c584
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Machen,TE
中科院分区：
文献类型：
--
作者：
Negulescu,PA;Munck,B;Machen,TE
应用Fura-2荧光数字图像处理技术，研究了应激诱导的细胞体积变化对兔胃腺壁细胞胞浆游离钙（CaI）的影响。在休息未刺激的细胞，蔡是不受细胞肿胀或收缩时，渗透压在200和400 mosM（等渗290 mosM）之间变化。然而，当细胞在165 mosM溶液（55%张力）中溶胀时，观察到双相Ca增加。平均而言，Cai从80 nM瞬时增加至218 nM，然后稳定在约140 nM。峰值是由于从细胞内池释放，因为它存在于无钙溶液中，而持续升高依赖于外部钙。在卡巴胆碱刺激的细胞中，Ca内流对细胞收缩最敏感。例如，添加25 mM蔗糖（108%张力）导致持续卡巴胆碱刺激的Cai增加（平台期）降低30%。相比之下，卡巴胆碱刺激的细胞对细胞肿胀相对不敏感，张力降低30%仅导致平台期增加15%。然而，在未受刺激的细胞中，极端（55%张力）肿胀引起Cai水平的额外增加。细胞体积变化对Cai的卡巴胆碱依赖性影响可以通过用毒胡萝卜素处理细胞来模拟，毒胡萝卜素是细胞内膜Ca泵的抑制剂，也已显示出刺激Ca进入。因此，尽管在存在或不存在激动剂的情况下极端溶胀条件（55%张力）可引起Cai增加，但需要激动剂来观察由于细胞收缩引起的Cai降低。（250字处删节）
The effects of osmotically induced changes in cell volume on cytoplasmic free Ca (Cai) were studied in parietal cells from intact rabbit gastric glands using digital image processing of fura-2 fluorescence. In resting unstimulated cells, Cai was unaffected by either cell swelling or shrinking when osmolarity was varied between 200 and 400 mosM (isotonicity 290 mosM). However, when cells were swelled in a 165 mosM solution (55% tonicity), a biphasic Ca increased was observed. On average, Cai increased transiently from 80 to 218 nM before stabilizing at approximately 140 nM. The peak was due to release from intracellular pools because it was present in Ca-free solutions while the sustained elevation was dependent on external Ca. In carbachol-stimulated cells, Ca influx was most sensitive to cell shrinkage. For example, addition of 25 mM sucrose (108% tonicity) caused a 30% decrease in the sustained carbachol-stimulated Cai increase (plateau). In contrast, carbachol-stimulated cells were relatively insensitive to cell swelling, with a 30% decrease in tonicity causing only a 15% increase in the plateau. However, as in the unstimulated cells, extreme (55% tonicity) swelling caused additional increases in Cai levels. The carbachol-dependent effects of changes in cell volume on Cai could be mimicked by treating cells with thapsigargin, an inhibitor of Ca pumps of intracellular membranes that also has been shown to stimulate Ca entry. Thus, although extreme swelling conditions (55% tonicity) could elicit Cai increases in either the presence or absence of agonist, agonist was required to observe Cai decreases due to cell shrinkage.(ABSTRACT TRUNCATED AT 250 WORDS)