Regulation of cytosolic free Ca2+ concentration in acinar cells of rat pancreas.
Regulation of cytosolic free Ca2+ concentration in acinar cells of rat pancreas.
复制标题
大鼠胰腺腺泡细胞胞质游离 Ca2+ 浓度的调节。
DOI：
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发表时间：
1983
影响因子：
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通讯作者：
I. Schulz
中科院分区：
文献类型：
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作者：
H. Streb;I. Schulz
通过用Ca 2+特异性电极测量周围孵育介质中游离Ca 2+浓度的降低来确定具有高渗透性质膜的分离的外分泌胰腺细胞的Ca 2+摄取。在存在Mg-ATP和呼吸底物的情况下，在加入渗漏细胞后，孵育培养基的游离Ca 2+浓度迅速下降，直到获得4.2 +/- 0.1 × 10（-7）mol/l的稳定培养基游离Ca 2+浓度。通过加入Ca 2+或EGTA在稳态下介质游离Ca 2+浓度的变化分别通过细胞摄取或释放缓冲，直到重新建立稳态游离Ca 2+浓度。当在线粒体抑制剂（10（-5）mol/l抗霉素、5 × 10（-6）mol/l寡霉素和10（-2）mol/l叠氮化物）的组合存在下测定非线粒体Ca 2+摄取时，摄取速率显著降低，而稳态浓度不变。相反，在ATP酶抑制剂钒酸盐（2 × 10（-3）mol/l）存在下，可以观察到线粒体摄取以与对照相同的速率进行，但达到的最低培养基游离Ca 2+浓度比对照高2.4 +/- 0.1 × 10（-7）mol/l。在稳态游离Ca 2+浓度下添加促分泌素导致0.73 +/- 0.08 nmol/mg蛋白质的Ca 2+释放。培养基中游离Ca 2+浓度的增加是完全短暂的，然后再摄取到预刺激水平。这些数据表明，在胰腺腺泡细胞中，4 × 10 ~（-7）mol/l的胞浆游离Ca ~（2+）浓度可由非线粒体Mg ~（2+）依赖性Ca ~（2+）池调节。
Ca2+ uptake into isolated exocrine pancreatic cells with highly permeable plasma membrane was determined by measuring the decrease in free Ca2+ concentration of the surrounding incubation medium with a Ca2+-specific electrode. In the presence of Mg-ATP and respiratory substrates the free Ca2+ concentration of the incubation medium decreased rapidly after addition of leaky cells until a stable medium free Ca2+ concentration of 4.2 +/- 0.1 X 10(-7) mol/l was obtained. Changes in the medium free Ca2+ concentration at steady state by addition of Ca2+ or EGTA were buffered by cellular uptake or release, respectively, until the steady-state free Ca2+ concentration was reestablished. When nonmitochondrial Ca2+ uptake was determined in the presence of a combination of mitochondrial inhibitors (10(-5) mol/l antimycin, 5 X 10(-6) mol/l oligomycin, and 10(-2) mol/l azide), the rate of uptake was considerably reduced, while the steady-state concentration was unaltered. In contrast, mitochondrial uptake that could be observed in the presence of the ATPase inhibitor vanadate (2 X 10(-3) mol/l) proceeded at the same rate as the control, but the minimal medium free Ca2+ concentration reached was 2.4 +/- 0.1 X 10(-7) mol/l higher than the control. Addition of secretagogues at steady-state free Ca2+ concentration resulted in a Ca2+ release of 0.73 +/- 0.08 nmol/mg protein. The increase in medium free Ca2+ concentration was entirely transient and followed by reuptake to the prestimulation level. The data indicate that a cytosolic free Ca2+ concentration of 4 X 10(-7) mol/l can be regulated in pancreatic acinar cells by a nonmitochondrial Mg2+-dependent Ca2+ pool.